Gr. Gala : Milk (genitive; galakta) -->Gr. galaktikos (milky)
.............................................-->L. galaxia (Milky way; Via Lactea)
L. Lac : Milk (genitive; lactis) (Fr Lait)
lactation : Suckling
lactose: Milk sugar; < Lact + ose (sugar suffix; hexose, pentose, triose, glucose...)
lactic acid: Milk acid; an acid obtained from sour milk
galactose: Brain sugar; a constituent of lactose
galactin: prolactin
5 Mart 2010 Cuma
2 Mart 2010 Salı
Unconscious decision-making
Neuroscientists Daniel Kahneman and Amos Tversky received a 2002 Nobel Prize for their 1979 research that argued humans rarely make rational decisions.
People do indeed make optimal decisions—but only when their unconscious brain makes the choice.
You don't consciously decide to stop at a red light or steer around an obstacle in the road. Once we started looking at the decisions our brains make without our knowledge, we found that they almost always reach the right decision, given the information they had to work with
A very simple unconscious-decision test.
A series of dots appears on a computer screen, most of which are moving in random directions. A controlled number of these dots are purposely moving uniformly in the same direction, and the test subject simply has to say whether he believes those dots are moving to the left or right. The longer the subject watches the dots, the more evidence he accumulates and the more sure he becomes of the dots' motion.
Subjects in this test performed exactly as if their brains were subconsciously gathering information before reaching a confidence threshold, which was then reported to the conscious mind as a definite, sure answer.
The subjects, however, were never aware of the complex computations going on, instead they simply "realized" suddenly that the dots were moving in one direction or another. Human brain is wired naturally to perform calculations of this kind.
A probabilistic decision-making system has several advantages. The most important is that it allows us to reach a reasonable decision in a reasonable amount of time. If we had to wait until we're 99 percent sure before we make a decision, then we would waste time accumulating data unnecessarily. If we only required a 51 percent certainty, then we might reach a decision before enough data has been collected.
Another main advantage is that when we finally reach a decision, we have a sense of how certain we are of it—say, 60 percent or 90 percent—depending on where the triggering threshold has been set.
The findings are published in the Dec 26 2008 issue of the journal "Neuron"
http://www.sciencedaily.com/releases/2008/12/081224215542.htm
People do indeed make optimal decisions—but only when their unconscious brain makes the choice.
You don't consciously decide to stop at a red light or steer around an obstacle in the road. Once we started looking at the decisions our brains make without our knowledge, we found that they almost always reach the right decision, given the information they had to work with
A very simple unconscious-decision test.
A series of dots appears on a computer screen, most of which are moving in random directions. A controlled number of these dots are purposely moving uniformly in the same direction, and the test subject simply has to say whether he believes those dots are moving to the left or right. The longer the subject watches the dots, the more evidence he accumulates and the more sure he becomes of the dots' motion.
Subjects in this test performed exactly as if their brains were subconsciously gathering information before reaching a confidence threshold, which was then reported to the conscious mind as a definite, sure answer.
The subjects, however, were never aware of the complex computations going on, instead they simply "realized" suddenly that the dots were moving in one direction or another. Human brain is wired naturally to perform calculations of this kind.
A probabilistic decision-making system has several advantages. The most important is that it allows us to reach a reasonable decision in a reasonable amount of time. If we had to wait until we're 99 percent sure before we make a decision, then we would waste time accumulating data unnecessarily. If we only required a 51 percent certainty, then we might reach a decision before enough data has been collected.
Another main advantage is that when we finally reach a decision, we have a sense of how certain we are of it—say, 60 percent or 90 percent—depending on where the triggering threshold has been set.
The findings are published in the Dec 26 2008 issue of the journal "Neuron"
http://www.sciencedaily.com/releases/2008/12/081224215542.htm
Delusions and right hemisphere
Delusions associated with consistent pattern of brain injury
How delusions arise and why they persist.
Patients with certain delusions and brain disorders reveals an injury to the frontal lobe and right hemisphere of the human brain. The cognitive deficits caused by these injuries to the right hemisphere, leads to the over-compensation by the left hemisphere, resulting in delusions.
The article entitled "Delusional misidentifications and duplications: Right brain lesions, left brain delusions" will appear in the latest issue of the journal of Neurology.
Problems caused by these right brain injuries include
~ impairment in monitoring of self
~ impairment in awareness of errors
~ incorrectly identifying what is familiar and what is a work of fiction
However, delusions result from the loss of these functions as well as the over activation of the left hemisphere and its language structures, that 'create a story', a story which cannot be edited and modified to account for reality.
Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded.
Often bizarre in content and held with absolute certainty, delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect.
Most neurologic patients with delusions usually have lesions in the right hemisphere and/or bifrontal areas. For example, the neurological disorders of
~ Confabulation (incorrect or distorted statements made without conscious effort to deceive),
~ Capgras (the ability to consciously recognize familiar faces but not emotionally connect with them) and
~ Prosopagnosia (patients who may fail to recognize spouses or their own face but generate an unconscious response to familiar faces) result from right sided lesions.
The right hemisphere of the brain dominates
~ self recognition,
~ emotional familiarity and
~ ego boundaries.
After injury, the left hemisphere tends to have a creative narrator leading to excessive, false explanations. The resistance of delusions to change despite clear evidence that they are wrong likely reflects frontal dysfunction of the brain, which impairs the ability to monitor self and to recognize and correct inaccurate memories and familiarity assessments. Thus, right hemisphere lesions may cause delusions by disrupting the relation between and the monitoring of psychic, emotional and physical self to people, places, and even body parts. This explains why content specific delusions involve people, places or things of personal significance and distort ones relation to oneself.
In one study, nine patients with right hemisphere infarctions at a stroke rehabilitation unit had frequent delusion. While size of the stroke did not correlate when compared to the control group, the presence of brain atrophy was a significant predictor of delusions. When delusions occurred, it was usually caused by a right hemisphere lesion. Also, one study pointed out that delusional patients with Alzheimer's disease usually have significantly more right frontal lobe damage.
Other research showed that Reduplicative Paramnesia and Capgras syndrome cases with unilateral brain lesions strongly implicate the right hemisphere, usually the frontal lobe of the brain. Among 69 patients with Reduplicative Paramnesia, lesions were primarily in the right hemisphere in 36 cases (52%), bilateral in 28 (41%) and left hemisphere in 5 (7%) -- a sevenfold increase of right over left-sided lesions. Similarly in 26 Capras patients, lesions were primarily in the right hemisphere in 8 (32 %), bilateral in 16 (62 %) and left sided in 2 (7%)- a four-fold increase of right - over left-sided lesions. For both delusional syndromes, many bilaterial cases had maximal damage in the right hemisphere.
Among another study of 29 cases of delusional misidentification syndromes, all patients had right hemisphere pathology, while 15 (52 %) had left hemisphere damage. Fourteen had exclusively right hemisphere damage but none had isolated left hemisphere damage. When lateralized lesions are found, right hemisphere lesions are more common in other delusional misidentification and content specific delusions. Frontal lesions are strongly implicated in misidentification syndromes. Exclusively frontal lesions were associated with delusions in 10 of 29 (34.5) cases- four with right frontal and six with bifrontal lesions. None had lesions sparing the frontal lobes.
Source:
New York University School of Medicine
January 13th, 2009
adapted from
http://www.physorg.com/news151069576.html
How delusions arise and why they persist.
Patients with certain delusions and brain disorders reveals an injury to the frontal lobe and right hemisphere of the human brain. The cognitive deficits caused by these injuries to the right hemisphere, leads to the over-compensation by the left hemisphere, resulting in delusions.
The article entitled "Delusional misidentifications and duplications: Right brain lesions, left brain delusions" will appear in the latest issue of the journal of Neurology.
Problems caused by these right brain injuries include
~ impairment in monitoring of self
~ impairment in awareness of errors
~ incorrectly identifying what is familiar and what is a work of fiction
However, delusions result from the loss of these functions as well as the over activation of the left hemisphere and its language structures, that 'create a story', a story which cannot be edited and modified to account for reality.
Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded.
Often bizarre in content and held with absolute certainty, delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect.
Most neurologic patients with delusions usually have lesions in the right hemisphere and/or bifrontal areas. For example, the neurological disorders of
~ Confabulation (incorrect or distorted statements made without conscious effort to deceive),
~ Capgras (the ability to consciously recognize familiar faces but not emotionally connect with them) and
~ Prosopagnosia (patients who may fail to recognize spouses or their own face but generate an unconscious response to familiar faces) result from right sided lesions.
The right hemisphere of the brain dominates
~ self recognition,
~ emotional familiarity and
~ ego boundaries.
After injury, the left hemisphere tends to have a creative narrator leading to excessive, false explanations. The resistance of delusions to change despite clear evidence that they are wrong likely reflects frontal dysfunction of the brain, which impairs the ability to monitor self and to recognize and correct inaccurate memories and familiarity assessments. Thus, right hemisphere lesions may cause delusions by disrupting the relation between and the monitoring of psychic, emotional and physical self to people, places, and even body parts. This explains why content specific delusions involve people, places or things of personal significance and distort ones relation to oneself.
In one study, nine patients with right hemisphere infarctions at a stroke rehabilitation unit had frequent delusion. While size of the stroke did not correlate when compared to the control group, the presence of brain atrophy was a significant predictor of delusions. When delusions occurred, it was usually caused by a right hemisphere lesion. Also, one study pointed out that delusional patients with Alzheimer's disease usually have significantly more right frontal lobe damage.
Other research showed that Reduplicative Paramnesia and Capgras syndrome cases with unilateral brain lesions strongly implicate the right hemisphere, usually the frontal lobe of the brain. Among 69 patients with Reduplicative Paramnesia, lesions were primarily in the right hemisphere in 36 cases (52%), bilateral in 28 (41%) and left hemisphere in 5 (7%) -- a sevenfold increase of right over left-sided lesions. Similarly in 26 Capras patients, lesions were primarily in the right hemisphere in 8 (32 %), bilateral in 16 (62 %) and left sided in 2 (7%)- a four-fold increase of right - over left-sided lesions. For both delusional syndromes, many bilaterial cases had maximal damage in the right hemisphere.
Among another study of 29 cases of delusional misidentification syndromes, all patients had right hemisphere pathology, while 15 (52 %) had left hemisphere damage. Fourteen had exclusively right hemisphere damage but none had isolated left hemisphere damage. When lateralized lesions are found, right hemisphere lesions are more common in other delusional misidentification and content specific delusions. Frontal lesions are strongly implicated in misidentification syndromes. Exclusively frontal lesions were associated with delusions in 10 of 29 (34.5) cases- four with right frontal and six with bifrontal lesions. None had lesions sparing the frontal lobes.
Source:
New York University School of Medicine
January 13th, 2009
adapted from
http://www.physorg.com/news151069576.html
24 Şubat 2010 Çarşamba
Cultural Neuroscience
Experiences can alter "hard-wired" brain structures. Through rehab, stroke patients can coax a region of the motor cortex on the opposite side of the damaged region to pinch-hit, restoring lost mobility; volunteers who are blindfolded for just five days can reprogram their visual cortex to process sound and touch.
The medial prefrontal cortex supposedly represents the self: it is active when we think of our own identity and traits. But with Chinese volunteers, the results were strikingly different. The "me" circuit hummed not only when they thought whether a particular adjective described themselves, but also when they considered whether it described their mother. The Westerners showed no such overlap between self and mom.
Depending whether one lives in a culture that views the self as autonomous and unique or as connected to and part of a larger whole, this neural circuit takes on quite different functions.
Westerners focus on individual objects while East Asians pay attention to context and background (another manifestation of the individualism- collectivism split). Sure enough, when shown complex, busy scenes, Asian-Americans and non-Asian--Americans recruited different brain regions. The Asians showed more activity in areas that process figure-ground relations—holistic context—while the Americans showed more activity in regions that recognize objects.
Drawings of people in a submissive pose (head down, shoulders hunched) or a dominant one (arms crossed, face forward) was shown to Japanese and Americans. The brain's dopamine-fueled reward circuit became most active at the sight of the stance—dominant for Americans, submissive for Japanese—that each volunteer's culture most values.
Chinese speakers use a different region of the brain to do simple arithmetic (3 + 4) or decide which number is larger than native English speakers do, even though both use Arabic numerals. The Chinese use the circuits that process visual and spatial information and plan movements (the latter may be related to the use of the abacus). But English speakers use language circuits. It is as if the West conceives numbers as just words, but the East imbues them with symbolic, spatial freight. (consider about Asian math geniuses.) Neural processes involving basic mathematical computations seem to be culture-specific.
from
Sharon Begley
West Brain, East Brain: What a difference culture makes.
Newsweek
Mar 1, 2010
http://www.newsweek.com/id/233778
The medial prefrontal cortex supposedly represents the self: it is active when we think of our own identity and traits. But with Chinese volunteers, the results were strikingly different. The "me" circuit hummed not only when they thought whether a particular adjective described themselves, but also when they considered whether it described their mother. The Westerners showed no such overlap between self and mom.
Depending whether one lives in a culture that views the self as autonomous and unique or as connected to and part of a larger whole, this neural circuit takes on quite different functions.
Westerners focus on individual objects while East Asians pay attention to context and background (another manifestation of the individualism- collectivism split). Sure enough, when shown complex, busy scenes, Asian-Americans and non-Asian--Americans recruited different brain regions. The Asians showed more activity in areas that process figure-ground relations—holistic context—while the Americans showed more activity in regions that recognize objects.
Drawings of people in a submissive pose (head down, shoulders hunched) or a dominant one (arms crossed, face forward) was shown to Japanese and Americans. The brain's dopamine-fueled reward circuit became most active at the sight of the stance—dominant for Americans, submissive for Japanese—that each volunteer's culture most values.
Chinese speakers use a different region of the brain to do simple arithmetic (3 + 4) or decide which number is larger than native English speakers do, even though both use Arabic numerals. The Chinese use the circuits that process visual and spatial information and plan movements (the latter may be related to the use of the abacus). But English speakers use language circuits. It is as if the West conceives numbers as just words, but the East imbues them with symbolic, spatial freight. (consider about Asian math geniuses.) Neural processes involving basic mathematical computations seem to be culture-specific.
from
Sharon Begley
West Brain, East Brain: What a difference culture makes.
Newsweek
Mar 1, 2010
http://www.newsweek.com/id/233778
5 Şubat 2010 Cuma
Coma should be redefined
A man with a severe traumatic brain injury remained physically unresponsive, and hence, was presumed to be in a vegetative state for six years. Now, it is understood that he is conscious and he can communicate yes and no via his thought patterns.
Using functional magnetic resonance imaging (fMRI), the patient's brain activity was mapped while he was asked to answer yes and no questions such as "Is your father's name Thomas?".
The researchers were astonished when they saw the results of the patient's scan. He
was able to correctly answer the questions that were asked by simply changing his thoughts, which they then decoded using our fMRI technique
The new technique can decode the brain's answers to such questions in healthy, non-vegetative, participants with 100 per cent accuracy.
But it has never before been tried in a patient who is in coma, hence, cannot move or speak.
In a three-year study, 23 patients diagnosed as vegetative were scanned. The new technique was able to detect signs of awareness in four of these cases.
However the researchers only managed to communicate, in the yes, no fashion, with one of the patients.
It's early days, but in future we hope to develop this technique to allow some patients to express their feelings and thoughts, control their environment and increase their quality of life
For example, patients who are aware, but cannot move or speak, could be asked if they are feeling any pain, allowing doctors to decide when painkillers should be administered
Recently, a Belgian man named Rom Houben who was wrongly diagnosed as comatose for 23years, is now planning to write a book about his extraordinary story. Since 2006, when his true condition was correctly diagnosed, Houben has regained enough coordination to allow him to use a finger, when aided, to tap out messages on a special computer keyboard.
Published in
New England Journal of Medicine
http://www.news.com.au/breaking-news/world/vegetative-man-communicates-via-scan/story-e6frfkui-1225826619059?from=news+newsletter_rss
**
Belgian man named Rom Houben was thought to have been in a coma (vegetative state) for 23 years (from 23 years of age to 46), however he was simply paralysed and unable to communicate. Finally doctors realised he was, in fact, conscious.
Cut off from the world, he passed his time in thought for years. He could hear what was being said around him throughout but was unable to respond.
"Doctors and nurses tried to speak to me and eventually gave up" The worst moment came when his mother and sister told him of the death of his father and though he wanted to weep, his body remained motionless.
After the correction of the diagnosis, he has regained enough coordination to allow him to use a finger, when aided, to use a special computer keyboard. Using a specially-adapted computer to type messages, Houben has been able to describe the ordeal he endured for more than two decades. He told that he meditated to pass the long years trapped in his own body. "I would scream, but no sound would come out," he said, "I will never forget the day they finally discovered what was wrong -- it was my second birth."
Houben is still unable to move, but he can read thanks to a device set up over his bed, and he communicates through a keyboard. "I want to read, to talk to my friends with the computer and to live life now people know I'm not dead," he said
There are too many cases inaccurately diagnosed coma -- more than 40 per cent in certain categories of sufferers. It is vital, with any coma patient, to discover whether they have plunged into a vegetative state or if there is some minimal consciousness
http://www.news.com.au/breaking-news/world/man-in-false-coma-plans-memoirs/story-e6frfkui-1225803497327
http://www.heraldsun.com.au/news/rom-houben-spent-more-than-twenty-years-in-what-doctors-thought-was-a-coma-but-he-was-actually-awake-and-paralysed/story-e6frf7jo-1225803146317
http://www.news.com.au/world/man-misdiagnosed-as-being-in-coma-for-23-years/story-e6frfkyi-1225803256170
Using functional magnetic resonance imaging (fMRI), the patient's brain activity was mapped while he was asked to answer yes and no questions such as "Is your father's name Thomas?".
The researchers were astonished when they saw the results of the patient's scan. He
was able to correctly answer the questions that were asked by simply changing his thoughts, which they then decoded using our fMRI technique
The new technique can decode the brain's answers to such questions in healthy, non-vegetative, participants with 100 per cent accuracy.
But it has never before been tried in a patient who is in coma, hence, cannot move or speak.
In a three-year study, 23 patients diagnosed as vegetative were scanned. The new technique was able to detect signs of awareness in four of these cases.
However the researchers only managed to communicate, in the yes, no fashion, with one of the patients.
It's early days, but in future we hope to develop this technique to allow some patients to express their feelings and thoughts, control their environment and increase their quality of life
For example, patients who are aware, but cannot move or speak, could be asked if they are feeling any pain, allowing doctors to decide when painkillers should be administered
Recently, a Belgian man named Rom Houben who was wrongly diagnosed as comatose for 23years, is now planning to write a book about his extraordinary story. Since 2006, when his true condition was correctly diagnosed, Houben has regained enough coordination to allow him to use a finger, when aided, to tap out messages on a special computer keyboard.
Published in
New England Journal of Medicine
http://www.news.com.au/breaking-news/world/vegetative-man-communicates-via-scan/story-e6frfkui-1225826619059?from=news+newsletter_rss
**
Belgian man named Rom Houben was thought to have been in a coma (vegetative state) for 23 years (from 23 years of age to 46), however he was simply paralysed and unable to communicate. Finally doctors realised he was, in fact, conscious.
Cut off from the world, he passed his time in thought for years. He could hear what was being said around him throughout but was unable to respond.
"Doctors and nurses tried to speak to me and eventually gave up" The worst moment came when his mother and sister told him of the death of his father and though he wanted to weep, his body remained motionless.
After the correction of the diagnosis, he has regained enough coordination to allow him to use a finger, when aided, to use a special computer keyboard. Using a specially-adapted computer to type messages, Houben has been able to describe the ordeal he endured for more than two decades. He told that he meditated to pass the long years trapped in his own body. "I would scream, but no sound would come out," he said, "I will never forget the day they finally discovered what was wrong -- it was my second birth."
Houben is still unable to move, but he can read thanks to a device set up over his bed, and he communicates through a keyboard. "I want to read, to talk to my friends with the computer and to live life now people know I'm not dead," he said
There are too many cases inaccurately diagnosed coma -- more than 40 per cent in certain categories of sufferers. It is vital, with any coma patient, to discover whether they have plunged into a vegetative state or if there is some minimal consciousness
http://www.news.com.au/breaking-news/world/man-in-false-coma-plans-memoirs/story-e6frfkui-1225803497327
http://www.heraldsun.com.au/news/rom-houben-spent-more-than-twenty-years-in-what-doctors-thought-was-a-coma-but-he-was-actually-awake-and-paralysed/story-e6frf7jo-1225803146317
http://www.news.com.au/world/man-misdiagnosed-as-being-in-coma-for-23-years/story-e6frfkyi-1225803256170
22 Ocak 2010 Cuma
Brain On A Chip?
How does the human brain run itself without any software?
They are building a ‘neural’ computer that will work just like the brain but on a much smaller scale in order to search this.
The human brain is often likened to a computer, but it differs from everyday computers in three important ways:
1- it consumes very little power,
2- it works well even if components fail,
3- it seems to work without any software.
The goal is to to build a ‘neural computer’ which emulates the brain. The first effort is a network of 300 neurons and half a million synapses on a single chip. The team used analogue electronics to represent the neurons and digital electronics to represent communications between them. It’s a unique combination.
Since the neurons are so small, the system runs 100,000 times faster than the biological equivalent and 10 million times faster than a software simulation. They can simulate a day in one second
The network is already being used by FACETS researchers to do experiments over the internet without needing to travel to Heidelberg.
New type of computing
Now the team are working on stage 2, a network of 200,000 neurons and 50 million synapses.
Beyond the brain?
Practical neural computers could be only five years away. Applications for neural computers are wherever there are complex and difficult decisions to be made. Companies could use them, for example, to explore the consequences of critical business decisions before they are taken.
The FACETS project, supported by the EU’s Sixth Framework Programme, is due to end in August 2009
Where could this go?
It is pointed out that neural computing, with its low-power demands and tolerance of faults, may make it possible to reduce components to molecular size publications
http://facets.kip.uni-heidelberg.de
http://www.sciencedaily.com/releases/2009/03/090318090142.htm
They are building a ‘neural’ computer that will work just like the brain but on a much smaller scale in order to search this.
The human brain is often likened to a computer, but it differs from everyday computers in three important ways:
1- it consumes very little power,
2- it works well even if components fail,
3- it seems to work without any software.
The goal is to to build a ‘neural computer’ which emulates the brain. The first effort is a network of 300 neurons and half a million synapses on a single chip. The team used analogue electronics to represent the neurons and digital electronics to represent communications between them. It’s a unique combination.
Since the neurons are so small, the system runs 100,000 times faster than the biological equivalent and 10 million times faster than a software simulation. They can simulate a day in one second
The network is already being used by FACETS researchers to do experiments over the internet without needing to travel to Heidelberg.
New type of computing
Now the team are working on stage 2, a network of 200,000 neurons and 50 million synapses.
Beyond the brain?
Practical neural computers could be only five years away. Applications for neural computers are wherever there are complex and difficult decisions to be made. Companies could use them, for example, to explore the consequences of critical business decisions before they are taken.
The FACETS project, supported by the EU’s Sixth Framework Programme, is due to end in August 2009
Where could this go?
It is pointed out that neural computing, with its low-power demands and tolerance of faults, may make it possible to reduce components to molecular size publications
http://facets.kip.uni-heidelberg.de
http://www.sciencedaily.com/releases/2009/03/090318090142.htm
Where internal milieu meets with extrapersonal space
There are many names for the same area of the brain. For instance:
Primary visual cortex (Functional name)
Striate cortex (Cytoarchitectonic name)
Calcarine cortex (Topographic name)
Area 17 (Brodman's parcellation)
or
Primary auditory cortex (Functional name)
Heschl gyrus (After the neuroscientist)
Area 41-42 (Brodman's parcellation)
Parcellation of the cortex by Brodman
Bradman's areas are cytoarchitectonic (microscopic) based, but functionally usable.
There are interindividual variances regarding these areas.
From a behavioral point of view, cerebral cortex can be divided into four;
1-Primary sensory cortex
2-Primary motor cortex
3-Association areas
4-Limbic-paralimbic cortex
3 and 4 are the most related areas of behaviour.
---
Here starts with internal milieu and ends with extrapersonal space
INTERNAL MILIEU
1-
Corticoid (cortexlike structures)
Simplest and differentiated type of cortex:
basal forebrain structures (ventral and medial surfaces);
~Septal nuclei
~Substantia Innominata
~Amygdaloid complex
2-
Allocortex
moderately differentiated layers.
~Archicortex: Hippocampus
~Paleocortex: Piriform cortex (primary olfactory cortex)
CORTICOID + ALLOCORTEX = LIMBIC ZONE OF CORTEX
3- Paralimbic zone (mesocortex)
Intercalated between isocortex and allocortex (transitional zone)
Periallocortical structures of the paralimbic areas.
Five major paralimbic formations:
-caudal orbitofrontal cortex
-insula
-temporal pole
-parahippocampal gyrus (entorhinal etc.)
-cingulate complex
Directing drive and emotion to the appropriate extrapersonal and intrapsychic targets
Paralimbic cortex acts as a relay between sensory association cortices and the limbic zone of the cortex
------------ --------- --------- --------- ---------
Here is the neural bridges that link the
internal milieu (inner world) and
extrapersonal space (outer world),
enabling the individual's need to be dyscharged
according to the limitations of the environment.
Integration of multimodal knowledge (heteromodal)
with drive and emotion (paralimbic)
------------ --------- --------- --------- ---------
4-Heteromodal association cortex
Perceptual elaboration and motor planning
Receives convergent input from multiple unimodal areas especially downstream
unimodal areas
5-Unimodal association cortex
Modality spesific elaboration and encoding of sensory input.
Peristriate region (18, 19) upstream unimodal association area
Inferotemporal cortex (20, 21) : downstream unimodal association area
6-Primary sensory and motor cortices
idiotypic, homogenos, and dedicated
EXTRAPERSONAL SPACE
Ahmet Corak, M.D., PhD.
adapted from
Mesulam M. Anatomic Principles in Cognitive Neuroscience.
In: Farah MJ, Feinberg TE.
Patient-based approaches to cognitive neuroscience
The MIT Press, 2000
Primary visual cortex (Functional name)
Striate cortex (Cytoarchitectonic name)
Calcarine cortex (Topographic name)
Area 17 (Brodman's parcellation)
or
Primary auditory cortex (Functional name)
Heschl gyrus (After the neuroscientist)
Area 41-42 (Brodman's parcellation)
Parcellation of the cortex by Brodman
Bradman's areas are cytoarchitectonic (microscopic) based, but functionally usable.
There are interindividual variances regarding these areas.
From a behavioral point of view, cerebral cortex can be divided into four;
1-Primary sensory cortex
2-Primary motor cortex
3-Association areas
4-Limbic-paralimbic cortex
3 and 4 are the most related areas of behaviour.
---
Here starts with internal milieu and ends with extrapersonal space
INTERNAL MILIEU
1-
Corticoid (cortexlike structures)
Simplest and differentiated type of cortex:
basal forebrain structures (ventral and medial surfaces);
~Septal nuclei
~Substantia Innominata
~Amygdaloid complex
2-
Allocortex
moderately differentiated layers.
~Archicortex: Hippocampus
~Paleocortex: Piriform cortex (primary olfactory cortex)
CORTICOID + ALLOCORTEX = LIMBIC ZONE OF CORTEX
3- Paralimbic zone (mesocortex)
Intercalated between isocortex and allocortex (transitional zone)
Periallocortical structures of the paralimbic areas.
Five major paralimbic formations:
-caudal orbitofrontal cortex
-insula
-temporal pole
-parahippocampal gyrus (entorhinal etc.)
-cingulate complex
Directing drive and emotion to the appropriate extrapersonal and intrapsychic targets
Paralimbic cortex acts as a relay between sensory association cortices and the limbic zone of the cortex
------------ --------- --------- --------- ---------
Here is the neural bridges that link the
internal milieu (inner world) and
extrapersonal space (outer world),
enabling the individual's need to be dyscharged
according to the limitations of the environment.
Integration of multimodal knowledge (heteromodal)
with drive and emotion (paralimbic)
------------ --------- --------- --------- ---------
4-Heteromodal association cortex
Perceptual elaboration and motor planning
Receives convergent input from multiple unimodal areas especially downstream
unimodal areas
5-Unimodal association cortex
Modality spesific elaboration and encoding of sensory input.
Peristriate region (18, 19) upstream unimodal association area
Inferotemporal cortex (20, 21) : downstream unimodal association area
6-Primary sensory and motor cortices
idiotypic, homogenos, and dedicated
EXTRAPERSONAL SPACE
Ahmet Corak, M.D., PhD.
adapted from
Mesulam M. Anatomic Principles in Cognitive Neuroscience.
In: Farah MJ, Feinberg TE.
Patient-based approaches to cognitive neuroscience
The MIT Press, 2000
Delusions and right hemisphere
Delusions associated with consistent pattern of brain injury
Source:
New York University School of Medicine
January 13th, 2009
How delusions arise and why they persist.
Patients with certain delusions and brain disorders reveals an injury to the frontal lobe and right hemisphere of the human brain. The cognitive deficits caused by these injuries to the right hemisphere, leads to the over-compensation by the left hemisphere, resulting in delusions.
The article entitled "Delusional misidentifications and duplications: Right brain lesions, left brain delusions" will appear in the latest issue of the journal of Neurology.
Problems caused by these right brain injuries include
~ impairment in monitoring of self
~ impairment in awareness of errors
~ incorrectly identifying what is familiar and what is a work of fiction
However, delusions result from the loss of these functions as well as the over activation of the left hemisphere and its language structures, that 'create a story', a story which cannot be edited and modified to account for reality.
Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded.
Often bizarre in content and held with absolute certainty, delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect.
Most neurologic patients with delusions usually have lesions in the right hemisphere and/or bifrontal areas. For example, the neurological disorders of
~ Confabulation (incorrect or distorted statements made without conscious effort to deceive),
~ Capgras (the ability to consciously recognize familiar faces but not emotionally connect with them) and
~ Prosopagnosia (patients who may fail to recognize spouses or their own face but generate an unconscious response to familiar faces) result from right sided lesions.
The right hemisphere of the brain dominates
~ self recognition,
~ emotional familiarity and
~ ego boundaries.
After injury, the left hemisphere tends to have a creative narrator leading to excessive, false explanations. The resistance of delusions to change despite clear evidence that they are wrong likely reflects frontal dysfunction of the brain, which impairs the ability to monitor self and to recognize and correct inaccurate memories and familiarity assessments. Thus, right hemisphere lesions may cause delusions by disrupting the relation between and the monitoring of psychic, emotional and physical self to people, places, and even body parts. This explains why content specific delusions involve people, places or things of personal significance and distort ones relation to oneself.
In one study, nine patients with right hemisphere infarctions at a stroke rehabilitation unit had frequent delusion. While size of the stroke did not correlate when compared to the control group, the presence of brain atrophy was a significant predictor of delusions. When delusions occurred, it was usually caused by a right hemisphere lesion. Also, one study pointed out that delusional patients with Alzheimer's disease usually have significantly more right frontal lobe damage.
Other research showed that Reduplicative Paramnesia and Capgras syndrome cases with unilateral brain lesions strongly implicate the right hemisphere, usually the frontal lobe of the brain. Among 69 patients with Reduplicative Paramnesia, lesions were primarily in the right hemisphere in 36 cases (52%), bilateral in 28 (41%) and left hemisphere in 5 (7%) -- a sevenfold increase of right over left-sided lesions. Similarly in 26 Capras patients, lesions were primarily in the right hemisphere in 8 (32 %), bilateral in 16 (62 %) and left sided in 2 (7%)- a four-fold increase of right - over left-sided lesions. For both delusional syndromes, many bilaterial cases had maximal damage in the right hemisphere.
Among another study of 29 cases of delusional misidentification syndromes, all patients had right hemisphere pathology, while 15 (52 %) had left hemisphere damage. Fourteen had exclusively right hemisphere damage but none had isolated left hemisphere damage. When lateralized lesions are found, right hemisphere lesions are more common in other delusional misidentification and content specific delusions. Frontal lesions are strongly implicated in misidentification syndromes. Exclusively frontal lesions were associated with delusions in 10 of 29 (34.5) cases- four with right frontal and six with bifrontal lesions. None had lesions sparing the frontal lobes.
adapted from
http://www.physorg.com/news151069576.html
Source:
New York University School of Medicine
January 13th, 2009
How delusions arise and why they persist.
Patients with certain delusions and brain disorders reveals an injury to the frontal lobe and right hemisphere of the human brain. The cognitive deficits caused by these injuries to the right hemisphere, leads to the over-compensation by the left hemisphere, resulting in delusions.
The article entitled "Delusional misidentifications and duplications: Right brain lesions, left brain delusions" will appear in the latest issue of the journal of Neurology.
Problems caused by these right brain injuries include
~ impairment in monitoring of self
~ impairment in awareness of errors
~ incorrectly identifying what is familiar and what is a work of fiction
However, delusions result from the loss of these functions as well as the over activation of the left hemisphere and its language structures, that 'create a story', a story which cannot be edited and modified to account for reality.
Delusions result from right hemisphere lesions, but it is the left hemisphere that is deluded.
Often bizarre in content and held with absolute certainty, delusions are pathologic beliefs that remain fixed despite clear evidence that they are incorrect.
Most neurologic patients with delusions usually have lesions in the right hemisphere and/or bifrontal areas. For example, the neurological disorders of
~ Confabulation (incorrect or distorted statements made without conscious effort to deceive),
~ Capgras (the ability to consciously recognize familiar faces but not emotionally connect with them) and
~ Prosopagnosia (patients who may fail to recognize spouses or their own face but generate an unconscious response to familiar faces) result from right sided lesions.
The right hemisphere of the brain dominates
~ self recognition,
~ emotional familiarity and
~ ego boundaries.
After injury, the left hemisphere tends to have a creative narrator leading to excessive, false explanations. The resistance of delusions to change despite clear evidence that they are wrong likely reflects frontal dysfunction of the brain, which impairs the ability to monitor self and to recognize and correct inaccurate memories and familiarity assessments. Thus, right hemisphere lesions may cause delusions by disrupting the relation between and the monitoring of psychic, emotional and physical self to people, places, and even body parts. This explains why content specific delusions involve people, places or things of personal significance and distort ones relation to oneself.
In one study, nine patients with right hemisphere infarctions at a stroke rehabilitation unit had frequent delusion. While size of the stroke did not correlate when compared to the control group, the presence of brain atrophy was a significant predictor of delusions. When delusions occurred, it was usually caused by a right hemisphere lesion. Also, one study pointed out that delusional patients with Alzheimer's disease usually have significantly more right frontal lobe damage.
Other research showed that Reduplicative Paramnesia and Capgras syndrome cases with unilateral brain lesions strongly implicate the right hemisphere, usually the frontal lobe of the brain. Among 69 patients with Reduplicative Paramnesia, lesions were primarily in the right hemisphere in 36 cases (52%), bilateral in 28 (41%) and left hemisphere in 5 (7%) -- a sevenfold increase of right over left-sided lesions. Similarly in 26 Capras patients, lesions were primarily in the right hemisphere in 8 (32 %), bilateral in 16 (62 %) and left sided in 2 (7%)- a four-fold increase of right - over left-sided lesions. For both delusional syndromes, many bilaterial cases had maximal damage in the right hemisphere.
Among another study of 29 cases of delusional misidentification syndromes, all patients had right hemisphere pathology, while 15 (52 %) had left hemisphere damage. Fourteen had exclusively right hemisphere damage but none had isolated left hemisphere damage. When lateralized lesions are found, right hemisphere lesions are more common in other delusional misidentification and content specific delusions. Frontal lesions are strongly implicated in misidentification syndromes. Exclusively frontal lesions were associated with delusions in 10 of 29 (34.5) cases- four with right frontal and six with bifrontal lesions. None had lesions sparing the frontal lobes.
adapted from
http://www.physorg.com/news151069576.html
16 Ocak 2010 Cumartesi
The outer limits of the human brain
EVEN the average human brain is remarkable. In adults it has perhaps 100 billion neurons, each connected to its neighbours by 5000 synapses or so.
A brain can make and break a million new connections each second.
It can store information for more than a century if you live that long, automatically cataloguing, re-filing and editing as needed. It can reconstruct our surroundings using a range of sensors that sample vibration, electromagnetic radiation, chemicals and pressure, and prioritise in milliseconds what might be of interest or concern.
It coordinates at least 640 muscles and looks after the essentials of energy generation, reproduction and survival with little thought, freeing our minds to socialise, ponder the meaning of our existence and learn from our experiences and those of people who we may never even have met.
High IQ
There were some positive correlations between hemisphere volume and score, the relationships varied with sex, handedness and type of test (Brain, vol 129, p 386). For example, verbal intelligence was positively correlated with cerebral volume in women and in right-handed men. And in women, visuospatial intelligence was positively linked with volume, but less strongly than verbal skills.
Women's brains are smaller than men's, even when corrected for body size, yet there is no consistent difference in men and women's IQs. IQ is so hard to measure at the extreme limits. Vos Savant's score (the most intelligent human being ever recorded in Guiness) varied from 186 to 228, depending on the test used, the conditions and the day.
PET scans showed that puzzles and tasks that provide a good measure of general intelligence (g) seem not to recruit vast areas of the brain as you might expect, but produce activity in a very specific region of the lateral frontal cortex (brain's G spot), the area associated with general intelligence, which is what IQ tests are thought to measure (Science, vol 289, p 457). In tasks that don't measure g very well, activity is more diffuse. It is not clear exactly what this finding means or what this region does.
Intelligence may also be connected to working memory, located in the middle and inferior frontal gyrus, a region near the brain's G spot. It is sometimes possible to train working memory with practice, and doing so may benefit IQ, especially fluid intelligence - the ability to solve new problems. However, this may just be a short cut to better IQ test scores rather than an indication of brain structures that confer intelligence.
In a research on the persons with IQs that were average (up to 108), high (up to 120) and superior (above 120) (Nature, vol 440, p 676), they found no differences in the overall thickness of the cerebral cortex attained by age 18. However, children in the average group had reached peak thickness by age 8, followed by a thinning down through adolescence, whereas in the superior group, the cortex was thinner at age 7 but continued thickening until age 11 or 12 before thinning again. The high group lay in between. It is concluded that intelligence is a dynamic process, related to a particularly high level of plasticity during these years.
A flair for language
ZIAD FAZAH claims to speak, read and write 59 languages - 10 at the tip of his tongue, and the others he reckons could be brushed up in a week. He is Lebanese, though his father was born in Colombia and he in Liberia. He moved to Lebanon as a baby, and growing up near a port, met and tried to converse with sailors of many nationalities. Fazah began learning French and English at school and decided at the age of 11 that he wanted to speak all the world's languages. So, over a three-year period during which he never left Lebanon, he studied more than 50 languages, several at a time, taking about three months to master each. Fazah had once wanted to work for the United Nations and has been approached by several intelligence agencies, but now he prefers the quiet life, working as a language teacher in Brazil.
What is the secret of such amazing linguistic talents? Fazah doesn't claim to be special, though he says his memory is "like a photographic camera", and he admits to a good deal of study. Anyone can speak a foreign language, he thinks. You need to spend 30 minutes each day listening carefully to the sounds of a native speaker, another 30 minutes studying the grammar and then 15 minutes reciting the sounds - a very important step. Recently he mastered a Caribbean creole in just a week, speaking well enough to be interviewed on local TV.
Fazah himself has never been near a brain scanner or taken part in any formal studies of his talents. Research on other polyglots, however, suggest there is no simple answer to what makes a brain linguistically gifted. The only consensus is that early exposure is a big advantage. If you don't form memories of language-specific sounds during the first year of life, the ability to recognise them may all but vanish, and learning becomes much more difficult (Nature Neuroscience, vol 1, p 351). Exposure to different grammars by the age of 7 also seems to leave open a window that makes it easier to learn later. On the other hand, acquiring vocabulary, say the experts, is simply down to memory and hard graft.
Scientific genius
Einstein's brain ended up in 240 pieces, packed into a couple of jars, and was carted around for years in the trunk of Princeton pathologist Harvey Thomas's car. Einstein's brain, at the time of his autopsy in 1955 (just 7 hours after his death), was reported by Thomas to appear unremarkable - it was a little shrunken with age, and slightly smaller than average. Nevertheless, Thomas carefully photographed and dissected it, and kept it preserved in formalin until science had new ways to scrutinise this amazing grey matter.
In the early 1980s, Some analysed some slides containing sections of Einstein's brain taken from the prefrontal and parietal lobes. These areas are part of the "association" cortex, which is involved with higher thought. Comparing the slides with similar tissue from 11 control brains, it is founded that Einstein's brain contained a greater than normal ratio of glial cells to neurons. Glial cells were until recently thought to be support cells for the neurons, important in providing energy and resources but not much more. They are now known to be involved in neural processing and signal transmission too. The absolute numbers were hard to measure, because of the way the tissue was preserved and sectioned, but Einstein's brain appeared to have double the normal number of glial cells in the left parietal region.
Diamond compared her findings to a case report of a mathematician whose brain was damaged in this same region so that he became unable to draw or write formulae, or to use a slide rule. Some eminent mathematicians say abstract concepts feel almost real, to the point that it is as if they exist in the brain and can be manipulated like real objects. Perhaps this region, which is known to be important for visuospatial cognition, is key.
There are other possibilities, however. Einstein claimed to be dyslexic and to have a poor memory for words. Damage to this region can cause dyslexia, so maybe his low neuron-to-glia ratio was a cause or result of his verbal difficulties rather than his reasoning skills.
Another study in the mid-1990s looked at the outer millimetre of cortical tissue from Einstein's right prefrontal lobe, a region that is associated with working memory, planning, regulation of intellectual function, and motor coordination. It is reported that the number and size of neurons here appeared normal, but that the cortex was thinner than average (2.1 millimetres compared with 2.6 millimetres in five control brains) making Einstein's cortical neurons more densely packed than usual. Anderson speculates that closer packing may speed up communication between neurons.
Then in 1998 from photos, and it appeared unremarkable except for the parietal lobes. Here the brain was 15 per cent wider than average, giving it a more spherical shape. In addition, two major grooves in this area were joined into one large furrow, which suggests the local circuitry was particularly highly integrated. While normal brains are asymmetrical, Einstein's parietal lobes were symmetrical. This all lends weight to the idea that his brain structure may have been unusual in some key areas that are important for spatial and reasoning skills.
In the brain tissue from three eminent scientists it is found that there were interesting patterns in the arrangement of cortical neurons (Autism, vol 11, p 557). The smallest processing module of neurons in the cortex is called a minicolumn - a vertical arrangement of cells that seem to work as a team. The scientists' minicolumns were smaller than those of controls, with less space between cells, meaning there were more processing units within any given cortical area. Computer modelling suggests that smaller processing units may allow for better signal detection and more focused attention. Small minicolumns are also seen in people with autism and Asperger's syndrome.
Long-stayers
The autopsy of a 115-year-old Dutch woman (Neurobiology of Aging, vol 29, p 1127) revealed little vascular damage, almost no build-up of the proteins linked to degenerative diseases such as Alzheimer's, and cell counts that seemed normal for an average 60 to 80 year old. The longevity of human cognition may extend far beyond most people's natural lifespan, conclude The longevity of human cognition may extend far beyond a natural lifespan
Ageing inevitably brings changes to the human brain. There is some decline in the blood vessels servicing it, and in the quantity of myelin, the fatty material that insulates the nerve fibres. The brain reduces slightly in volume, the grooves all over its surface widen, and there's a slight expansion of the cavities called ventricles. Age also brings a reduction in the speed at which nerve signals travel and there is a general decrease in coordination between different brain regions, which could explain why a person's memory can seem ever more challenged. However, while memory may start to decline as early as our 20s or 30s, according to psychologists, experience and general knowledge compensate until at least our 50s or 60s. What's more, functional imaging shows that often performance in cognitive tasks is maintained, at least to some extent, because the older brain compensates for any reduction in activity in specific regions by recruiting more areas to work on the problem.
Some researchers have suggested that dementia is almost inevitable in an aged brain. That view is being challenged as more and more sprightly centenarians have been found to have quite healthy minds and brains. There are no simple recipes for a long mental life - some risk factors for dementia run in families, others are spontaneous or build up over a lifetime - but high blood pressure, obesity and heart problems all increase the risk of stroke and dementia, while exercise and mental activity seem to reduce it. But clearly, old brains can show remarkable staying power.
Extraordinary talents
GLOBALLY there are around 100 "prodigious savants", who show one remarkable skill in complete isolation to their other mental functions. Savants either have autism or have suffered brain damage at birth or later in life, and their general intelligence, excepting their remarkable skill, is poorer than average. Some have photographic memories of complex scenes and can draw or sculpt unbelievably accurate representations. Others can calculate numbers, squares, primes or calendar dates. Some can remember entire books and some can rattle off a piano concerto after a single hearing. Yet others can draw perfect circles. What leads to such islands of intelligence?
There are many theories. Savants always have amazing recall in some sphere or other, though the neuropsychological basis of this is not clear. Some researchers claim that practice, which is clearly obsessive and focused in some savants, could explain their skills. Others believe that developmental errors in the brain leave a few rare people with an incredible focus on detail, while losing the more general view. This might be because of damage, or perhaps an unusual pattern of connectivity in the left hemisphere, which sees the big picture, with overcompensation by the more detail-conscious right. Certainly, injury to the left hemisphere can lead to symptoms of autism, and MRI scans of people with autism suggest differences in white matter, with hyperconnectivity in some regions but fewer connections overall.
However, research by Allan Snyder from the Centre for the Mind in Sydney, Australia, has convinced him that savant-like skills lie within us all. He believes they result from a shutting down of some of the higher-order, "rule-based" cognition, which usually makes thinking more efficient and generalisable. These higher cortical functions normally turn large amounts of basic subconscious information into useful conscious concepts. Snyder has used transcranial magnetic stimulation - a blast of magnetic pulses that temporarily and harmlessly interrupts higher brain functions - to inactivate a small area of the cortex in volunteers, who he then asks to draw, proof-read or perform difficult calculations. He claims that this improves these skills in ordinary people. If Snyder is correct, the outer limits of some of our memory and information-processing capacities may only be revealed when parts of the brain are inactivated.
Savant-like skills may result from shutting down higher-order cognition
Athletic minds
THE bodies of athletes are clearly special - the result of good genes and lots of hard graft - but what about their brains? Is there any grey-matter advantage that helps the likes of Usain Bolt and Michael Phelps to outperform their rivals?
Many sports require specific patterns of stereotypical body movements, and these certainly leave their mark on the brain. In the somatosensory cortex, which monitors signals from different parts of the body, and the neighbouring motor cortex, which controls movements, areas corresponding to the most regularly used body parts expand with use.
Good hand-eye coordination can also be traced to a specific part of the brain. Tests in the lab using prisms that alter hand-eye relationships by shifting images to the right or left or turning them upside down, reveal that some people adapt more quickly than others. Those with more dynamic hand-eye coordination show greater activity in a region called PEG in the parietal cortex - which contains maps of space and of our bodies - on the opposite side to the movement.
Some people may also have brains that allow them to keep on going when lesser competitors give up. The sensation of tiredness we get from sporting activity seems to be generated not in the muscles but in the brain, through a signalling molecule called interleukin-6. Perhaps this signal is naturally weaker or easier to ignore in some brains. If so, this might be why some athletes can push their bodies beyond the limits that most people are able to endure.
Memory marvels
FOR anyone who goes through life forgetting where they left their keys, the outer limits of human memory are truly mind-blowing. Take AJ who is in her 40s and can remember every day of her life since her teens. Or Kim Peek, the real-life inspiration for the film Rain Man, who has memorised at least 7600 books and countless zip codes and telephone area codes. Then there's Ben Pridmore, an accountant from Derby, UK, who has just smashed three world records for remembering 930 binary digits in 5 minutes, 819 digits in 15 minutes and 364 playing cards in 10 minutes.
Recall like AJ's may indicate that the normal process of memory pruning has gone awry. Autobiographical memories are held temporarily in the hippocampus and then those that are not reinforced or recalled are gradually thrown away and the rest are shifted into longer-term stores in other brain regions. However, many experts believe that differences in memory owe nothing to innate structures or special neurophysiology and everything to skills that are developed. Memory marvels often use tried and tested techniques, such as mnemonics, rhymes or visualisation to help stamp memories into their grey matter. Others may use obsessive rehearsal - this can happen strategically or as a result of mental illness or brain damage. A good memory requires effort and attention not special grey matter.
A good memory requires effort and attention not special grey matter
Supersenses
WHILE most of us have three types of colour receptors in our eyes, some people have four. This gives them an extra dimension to their colour perception. All these so-called tetrachromats are women, because the genes involved are on the X chromosomes. One person studied was an interior decorator, and was sensitive to colours within the range most people would see as just beige - so perhaps this supersense isn't always an advantage.
Then there are super-tasters, whose enhanced taste comes from having more than the average number of tastebuds. And acute hearing is common to most young adults, who can hear frequencies up to 20,000 hertz as compared with 8000 in the elderly. However, there is nothing special about the brains of supersensors. The human sensory cortex seems to be able to handle whatever information the sense organs can throw at it - the limits are down to the information coming in, not the grey matter that handles it.
But there is one way that the brain itself seems to stretch the boundaries of the sensors in a condition known as synaesthesia. Here the sensory experiences merge, as one sensation recruits others. Some people experience colours when they hear certain sounds or see words and numbers. Others hear sounds with touch sensations, or experience shapes with tastes. One theory for why this happens is heightened connectivity between different sensory areas in the brain (Neuron, vol 48, p 509).
Up to 1 in 23 people are synaesthesic and it runs in families, indicating a genetic component. However, our everyday use of mixed sensory metaphors such as "sharp tastes" or "soft sounds" indicates that this is one extraordinary mental ability that we may all experience to some extent at least.
01 October 2008 by Helen Phillips
NewScientist, issue 2676
A brain can make and break a million new connections each second.
It can store information for more than a century if you live that long, automatically cataloguing, re-filing and editing as needed. It can reconstruct our surroundings using a range of sensors that sample vibration, electromagnetic radiation, chemicals and pressure, and prioritise in milliseconds what might be of interest or concern.
It coordinates at least 640 muscles and looks after the essentials of energy generation, reproduction and survival with little thought, freeing our minds to socialise, ponder the meaning of our existence and learn from our experiences and those of people who we may never even have met.
High IQ
There were some positive correlations between hemisphere volume and score, the relationships varied with sex, handedness and type of test (Brain, vol 129, p 386). For example, verbal intelligence was positively correlated with cerebral volume in women and in right-handed men. And in women, visuospatial intelligence was positively linked with volume, but less strongly than verbal skills.
Women's brains are smaller than men's, even when corrected for body size, yet there is no consistent difference in men and women's IQs. IQ is so hard to measure at the extreme limits. Vos Savant's score (the most intelligent human being ever recorded in Guiness) varied from 186 to 228, depending on the test used, the conditions and the day.
PET scans showed that puzzles and tasks that provide a good measure of general intelligence (g) seem not to recruit vast areas of the brain as you might expect, but produce activity in a very specific region of the lateral frontal cortex (brain's G spot), the area associated with general intelligence, which is what IQ tests are thought to measure (Science, vol 289, p 457). In tasks that don't measure g very well, activity is more diffuse. It is not clear exactly what this finding means or what this region does.
Intelligence may also be connected to working memory, located in the middle and inferior frontal gyrus, a region near the brain's G spot. It is sometimes possible to train working memory with practice, and doing so may benefit IQ, especially fluid intelligence - the ability to solve new problems. However, this may just be a short cut to better IQ test scores rather than an indication of brain structures that confer intelligence.
In a research on the persons with IQs that were average (up to 108), high (up to 120) and superior (above 120) (Nature, vol 440, p 676), they found no differences in the overall thickness of the cerebral cortex attained by age 18. However, children in the average group had reached peak thickness by age 8, followed by a thinning down through adolescence, whereas in the superior group, the cortex was thinner at age 7 but continued thickening until age 11 or 12 before thinning again. The high group lay in between. It is concluded that intelligence is a dynamic process, related to a particularly high level of plasticity during these years.
A flair for language
ZIAD FAZAH claims to speak, read and write 59 languages - 10 at the tip of his tongue, and the others he reckons could be brushed up in a week. He is Lebanese, though his father was born in Colombia and he in Liberia. He moved to Lebanon as a baby, and growing up near a port, met and tried to converse with sailors of many nationalities. Fazah began learning French and English at school and decided at the age of 11 that he wanted to speak all the world's languages. So, over a three-year period during which he never left Lebanon, he studied more than 50 languages, several at a time, taking about three months to master each. Fazah had once wanted to work for the United Nations and has been approached by several intelligence agencies, but now he prefers the quiet life, working as a language teacher in Brazil.
What is the secret of such amazing linguistic talents? Fazah doesn't claim to be special, though he says his memory is "like a photographic camera", and he admits to a good deal of study. Anyone can speak a foreign language, he thinks. You need to spend 30 minutes each day listening carefully to the sounds of a native speaker, another 30 minutes studying the grammar and then 15 minutes reciting the sounds - a very important step. Recently he mastered a Caribbean creole in just a week, speaking well enough to be interviewed on local TV.
Fazah himself has never been near a brain scanner or taken part in any formal studies of his talents. Research on other polyglots, however, suggest there is no simple answer to what makes a brain linguistically gifted. The only consensus is that early exposure is a big advantage. If you don't form memories of language-specific sounds during the first year of life, the ability to recognise them may all but vanish, and learning becomes much more difficult (Nature Neuroscience, vol 1, p 351). Exposure to different grammars by the age of 7 also seems to leave open a window that makes it easier to learn later. On the other hand, acquiring vocabulary, say the experts, is simply down to memory and hard graft.
Scientific genius
Einstein's brain ended up in 240 pieces, packed into a couple of jars, and was carted around for years in the trunk of Princeton pathologist Harvey Thomas's car. Einstein's brain, at the time of his autopsy in 1955 (just 7 hours after his death), was reported by Thomas to appear unremarkable - it was a little shrunken with age, and slightly smaller than average. Nevertheless, Thomas carefully photographed and dissected it, and kept it preserved in formalin until science had new ways to scrutinise this amazing grey matter.
In the early 1980s, Some analysed some slides containing sections of Einstein's brain taken from the prefrontal and parietal lobes. These areas are part of the "association" cortex, which is involved with higher thought. Comparing the slides with similar tissue from 11 control brains, it is founded that Einstein's brain contained a greater than normal ratio of glial cells to neurons. Glial cells were until recently thought to be support cells for the neurons, important in providing energy and resources but not much more. They are now known to be involved in neural processing and signal transmission too. The absolute numbers were hard to measure, because of the way the tissue was preserved and sectioned, but Einstein's brain appeared to have double the normal number of glial cells in the left parietal region.
Diamond compared her findings to a case report of a mathematician whose brain was damaged in this same region so that he became unable to draw or write formulae, or to use a slide rule. Some eminent mathematicians say abstract concepts feel almost real, to the point that it is as if they exist in the brain and can be manipulated like real objects. Perhaps this region, which is known to be important for visuospatial cognition, is key.
There are other possibilities, however. Einstein claimed to be dyslexic and to have a poor memory for words. Damage to this region can cause dyslexia, so maybe his low neuron-to-glia ratio was a cause or result of his verbal difficulties rather than his reasoning skills.
Another study in the mid-1990s looked at the outer millimetre of cortical tissue from Einstein's right prefrontal lobe, a region that is associated with working memory, planning, regulation of intellectual function, and motor coordination. It is reported that the number and size of neurons here appeared normal, but that the cortex was thinner than average (2.1 millimetres compared with 2.6 millimetres in five control brains) making Einstein's cortical neurons more densely packed than usual. Anderson speculates that closer packing may speed up communication between neurons.
Then in 1998 from photos, and it appeared unremarkable except for the parietal lobes. Here the brain was 15 per cent wider than average, giving it a more spherical shape. In addition, two major grooves in this area were joined into one large furrow, which suggests the local circuitry was particularly highly integrated. While normal brains are asymmetrical, Einstein's parietal lobes were symmetrical. This all lends weight to the idea that his brain structure may have been unusual in some key areas that are important for spatial and reasoning skills.
In the brain tissue from three eminent scientists it is found that there were interesting patterns in the arrangement of cortical neurons (Autism, vol 11, p 557). The smallest processing module of neurons in the cortex is called a minicolumn - a vertical arrangement of cells that seem to work as a team. The scientists' minicolumns were smaller than those of controls, with less space between cells, meaning there were more processing units within any given cortical area. Computer modelling suggests that smaller processing units may allow for better signal detection and more focused attention. Small minicolumns are also seen in people with autism and Asperger's syndrome.
Long-stayers
The autopsy of a 115-year-old Dutch woman (Neurobiology of Aging, vol 29, p 1127) revealed little vascular damage, almost no build-up of the proteins linked to degenerative diseases such as Alzheimer's, and cell counts that seemed normal for an average 60 to 80 year old. The longevity of human cognition may extend far beyond most people's natural lifespan, conclude The longevity of human cognition may extend far beyond a natural lifespan
Ageing inevitably brings changes to the human brain. There is some decline in the blood vessels servicing it, and in the quantity of myelin, the fatty material that insulates the nerve fibres. The brain reduces slightly in volume, the grooves all over its surface widen, and there's a slight expansion of the cavities called ventricles. Age also brings a reduction in the speed at which nerve signals travel and there is a general decrease in coordination between different brain regions, which could explain why a person's memory can seem ever more challenged. However, while memory may start to decline as early as our 20s or 30s, according to psychologists, experience and general knowledge compensate until at least our 50s or 60s. What's more, functional imaging shows that often performance in cognitive tasks is maintained, at least to some extent, because the older brain compensates for any reduction in activity in specific regions by recruiting more areas to work on the problem.
Some researchers have suggested that dementia is almost inevitable in an aged brain. That view is being challenged as more and more sprightly centenarians have been found to have quite healthy minds and brains. There are no simple recipes for a long mental life - some risk factors for dementia run in families, others are spontaneous or build up over a lifetime - but high blood pressure, obesity and heart problems all increase the risk of stroke and dementia, while exercise and mental activity seem to reduce it. But clearly, old brains can show remarkable staying power.
Extraordinary talents
GLOBALLY there are around 100 "prodigious savants", who show one remarkable skill in complete isolation to their other mental functions. Savants either have autism or have suffered brain damage at birth or later in life, and their general intelligence, excepting their remarkable skill, is poorer than average. Some have photographic memories of complex scenes and can draw or sculpt unbelievably accurate representations. Others can calculate numbers, squares, primes or calendar dates. Some can remember entire books and some can rattle off a piano concerto after a single hearing. Yet others can draw perfect circles. What leads to such islands of intelligence?
There are many theories. Savants always have amazing recall in some sphere or other, though the neuropsychological basis of this is not clear. Some researchers claim that practice, which is clearly obsessive and focused in some savants, could explain their skills. Others believe that developmental errors in the brain leave a few rare people with an incredible focus on detail, while losing the more general view. This might be because of damage, or perhaps an unusual pattern of connectivity in the left hemisphere, which sees the big picture, with overcompensation by the more detail-conscious right. Certainly, injury to the left hemisphere can lead to symptoms of autism, and MRI scans of people with autism suggest differences in white matter, with hyperconnectivity in some regions but fewer connections overall.
However, research by Allan Snyder from the Centre for the Mind in Sydney, Australia, has convinced him that savant-like skills lie within us all. He believes they result from a shutting down of some of the higher-order, "rule-based" cognition, which usually makes thinking more efficient and generalisable. These higher cortical functions normally turn large amounts of basic subconscious information into useful conscious concepts. Snyder has used transcranial magnetic stimulation - a blast of magnetic pulses that temporarily and harmlessly interrupts higher brain functions - to inactivate a small area of the cortex in volunteers, who he then asks to draw, proof-read or perform difficult calculations. He claims that this improves these skills in ordinary people. If Snyder is correct, the outer limits of some of our memory and information-processing capacities may only be revealed when parts of the brain are inactivated.
Savant-like skills may result from shutting down higher-order cognition
Athletic minds
THE bodies of athletes are clearly special - the result of good genes and lots of hard graft - but what about their brains? Is there any grey-matter advantage that helps the likes of Usain Bolt and Michael Phelps to outperform their rivals?
Many sports require specific patterns of stereotypical body movements, and these certainly leave their mark on the brain. In the somatosensory cortex, which monitors signals from different parts of the body, and the neighbouring motor cortex, which controls movements, areas corresponding to the most regularly used body parts expand with use.
Good hand-eye coordination can also be traced to a specific part of the brain. Tests in the lab using prisms that alter hand-eye relationships by shifting images to the right or left or turning them upside down, reveal that some people adapt more quickly than others. Those with more dynamic hand-eye coordination show greater activity in a region called PEG in the parietal cortex - which contains maps of space and of our bodies - on the opposite side to the movement.
Some people may also have brains that allow them to keep on going when lesser competitors give up. The sensation of tiredness we get from sporting activity seems to be generated not in the muscles but in the brain, through a signalling molecule called interleukin-6. Perhaps this signal is naturally weaker or easier to ignore in some brains. If so, this might be why some athletes can push their bodies beyond the limits that most people are able to endure.
Memory marvels
FOR anyone who goes through life forgetting where they left their keys, the outer limits of human memory are truly mind-blowing. Take AJ who is in her 40s and can remember every day of her life since her teens. Or Kim Peek, the real-life inspiration for the film Rain Man, who has memorised at least 7600 books and countless zip codes and telephone area codes. Then there's Ben Pridmore, an accountant from Derby, UK, who has just smashed three world records for remembering 930 binary digits in 5 minutes, 819 digits in 15 minutes and 364 playing cards in 10 minutes.
Recall like AJ's may indicate that the normal process of memory pruning has gone awry. Autobiographical memories are held temporarily in the hippocampus and then those that are not reinforced or recalled are gradually thrown away and the rest are shifted into longer-term stores in other brain regions. However, many experts believe that differences in memory owe nothing to innate structures or special neurophysiology and everything to skills that are developed. Memory marvels often use tried and tested techniques, such as mnemonics, rhymes or visualisation to help stamp memories into their grey matter. Others may use obsessive rehearsal - this can happen strategically or as a result of mental illness or brain damage. A good memory requires effort and attention not special grey matter.
A good memory requires effort and attention not special grey matter
Supersenses
WHILE most of us have three types of colour receptors in our eyes, some people have four. This gives them an extra dimension to their colour perception. All these so-called tetrachromats are women, because the genes involved are on the X chromosomes. One person studied was an interior decorator, and was sensitive to colours within the range most people would see as just beige - so perhaps this supersense isn't always an advantage.
Then there are super-tasters, whose enhanced taste comes from having more than the average number of tastebuds. And acute hearing is common to most young adults, who can hear frequencies up to 20,000 hertz as compared with 8000 in the elderly. However, there is nothing special about the brains of supersensors. The human sensory cortex seems to be able to handle whatever information the sense organs can throw at it - the limits are down to the information coming in, not the grey matter that handles it.
But there is one way that the brain itself seems to stretch the boundaries of the sensors in a condition known as synaesthesia. Here the sensory experiences merge, as one sensation recruits others. Some people experience colours when they hear certain sounds or see words and numbers. Others hear sounds with touch sensations, or experience shapes with tastes. One theory for why this happens is heightened connectivity between different sensory areas in the brain (Neuron, vol 48, p 509).
Up to 1 in 23 people are synaesthesic and it runs in families, indicating a genetic component. However, our everyday use of mixed sensory metaphors such as "sharp tastes" or "soft sounds" indicates that this is one extraordinary mental ability that we may all experience to some extent at least.
01 October 2008 by Helen Phillips
NewScientist, issue 2676
Mirror Neurons
Humans, primates, some birds, and possibly other higher animals have mirror neurons that fire in the same pattern whether performing or just observing a task.
These mirror neurons clearly play an important role in learning motor tasks involving hand eye coordination, and possibly also acquisition of language skills, as well as being required for social skills.
Knowledge in this field could shed light on problems such as autism that may arise when this process goes wrong.
The role of mirror neurons at all levels of social interaction is even greater than had been realized. Mirror mechanism is crucial for emotional recognition and empathy"
Just as the same mirror neurons fire when observing and doing certain tasks, so other mirror neurons may be triggered both when experiencing a particularly emotion and when observing someone else with that emotion.
Mirror neurons involved in emotion resided in both the insula and cingulate cortexes, two regions of the brain known to play roles in emotions and feelings.
In the case of emotions, we can say that there is a good deal of overlap between areas from the insula and cingulate cortexes. These areas become active both when individuals feel an emotion (e.g. disgust) and also when they watch someone else feeling that emotion."
Mirror neurons were discovered in the 1980s by Giacomo Rizzolatti, which placed electrodes in the inferior frontal cortex of macaque monkeys' brains to study neurons dedicated to control of hand movement. This led to the surprising observation that some of the neurons responded in the same way when monkeys saw a person pick up a piece of food as when they were doing it themselves. This introduced the principle of the mirror neuron as a neuron capable of being triggered by imitation, as a mechanism both for learning and empathising in social situations.
While mirror neurons cannot be observed directly in humans because electrodes cannot be inserted into their brains, the action has been inferred by imaging of the whole brain using magnetic resonance imaging (MRI). This showed patterns of brain activity consistent with the firing of motor neurons.
More recently motor neurons have also been discovered in birds. This suggests that such a sensory-motor mechanism is not confined to primates, but is shared by different phyla. However the mechanism is not thought to be present in more primitive animals, including the lower cold blooded vertebrates, that is fish, reptiles and amphibians.
Mirror neurons is closely related with mind-reading abilities.
ScienceDaily (Dec. 21, 2008)
These mirror neurons clearly play an important role in learning motor tasks involving hand eye coordination, and possibly also acquisition of language skills, as well as being required for social skills.
Knowledge in this field could shed light on problems such as autism that may arise when this process goes wrong.
The role of mirror neurons at all levels of social interaction is even greater than had been realized. Mirror mechanism is crucial for emotional recognition and empathy"
Just as the same mirror neurons fire when observing and doing certain tasks, so other mirror neurons may be triggered both when experiencing a particularly emotion and when observing someone else with that emotion.
Mirror neurons involved in emotion resided in both the insula and cingulate cortexes, two regions of the brain known to play roles in emotions and feelings.
In the case of emotions, we can say that there is a good deal of overlap between areas from the insula and cingulate cortexes. These areas become active both when individuals feel an emotion (e.g. disgust) and also when they watch someone else feeling that emotion."
Mirror neurons were discovered in the 1980s by Giacomo Rizzolatti, which placed electrodes in the inferior frontal cortex of macaque monkeys' brains to study neurons dedicated to control of hand movement. This led to the surprising observation that some of the neurons responded in the same way when monkeys saw a person pick up a piece of food as when they were doing it themselves. This introduced the principle of the mirror neuron as a neuron capable of being triggered by imitation, as a mechanism both for learning and empathising in social situations.
While mirror neurons cannot be observed directly in humans because electrodes cannot be inserted into their brains, the action has been inferred by imaging of the whole brain using magnetic resonance imaging (MRI). This showed patterns of brain activity consistent with the firing of motor neurons.
More recently motor neurons have also been discovered in birds. This suggests that such a sensory-motor mechanism is not confined to primates, but is shared by different phyla. However the mechanism is not thought to be present in more primitive animals, including the lower cold blooded vertebrates, that is fish, reptiles and amphibians.
Mirror neurons is closely related with mind-reading abilities.
ScienceDaily (Dec. 21, 2008)
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