Critical Review: His Brain, Her Brain
1 Critical Review No. 2: His Brain, Her Brain
Abstract
As Larry Cahill 's article “His Brain, Her Brain”, points out there has been data showing a vast “...array of structural, chemical and functional variations” between the sexes; but does size matter? Lawrence Summers, former President of Harvard, thought so. Men 's brains are 13% larger than women 's brains, but does that really make them more advanced in math, physics and science? There are other anatomical variations and some of these are found to influence the way male and female brains work. Scientists have spent decades studying the brain and trying to answer questions regarding brain function. Trying to answer what actions are nature or nurture. Why do men and women act so …show more content…
differently? There have been great strives in research, since Seymour Levine 's 1966 hormonal theory.
They are now closer than ever to understanding functions of the brain and sex-specific functions. Some of these new sex-specific findings are leading scientists to a new array of questions; such as, whether or not we need to take into account gender or run the risk of getting inaccurate data in trials and experiments. Are there better sex-specific treatments we could be using in medicine? Conditions like PTSD (Post-Traumatic Stress Disorder), depression, schizophrenia, etc. may have better treatment plans. To understand this, we must understand the roots of sex-specific studies into the brain. Cahill enlightens us on what we have discovered.
2 Critical Review No. 2: His Brain, Her Brain
Are men better at math, physics and science because of merely the size of their brains? Lawrence Summers, President of Harvard (at the time), caused quite a stir when he stated that men were. Does size really matter in these subjects? Yes, men 's brains are generally in whole 13% larger than women 's, that is a scientific fact. Nineteenth-century enthusiasm for brain size as a simple measure of human performance was championed by some remarkably astute scientists (including Darwin 's cousin Francis Galton and the French neurologist Paul Broca), as well as others whose motives and methods are now suspect. Broca, one of the great neurologists of his day and a gifted observer, not only thought that brain size reflected intelligence, but was of the opinion (as was just about every other nineteenth-century male scientist) that white European males had larger and better-developed brains than anyone else. but this is a new age, a time of new discoveries, new studies and scientific findings. New experiments and data, along with technological developments have brought us out of the dark age.
As Larry Cahill 's article “His Brain, Her Brain”, points out there has been data showing a vast “...array of structural, chemical and functional variations” between the sexes; but no data that these disparities hinder women 's ability to excel in any of these subjects. He does examine many of the findings between the two sexes, pointing out many variations and yes, there are anatomical differences that do influence the way male and female brains work but there is no proof or data to support Summers, structurally, anatomically, chemically and/or functionally.
Scientists have spent decades studying the brain and trying to answer questions regarding the brain. Trying to answer whether cognitive actions or behavior are traits of nature or nurture. Does the brain have sex-specific variances? There have been great strives Seymour Levine of Stanford University 's 1966 theory until now. Cahill enlightens us on the “new” sex-specific brain.
At first, it was believed some of the varying functions of the brain, between the sexes, were limited to only the region having to do with mating hormones. These hormones are produced in a small area at the base of the brain, called hypothalamus. The hypothalamus regulates our hormones and also, basic instincts, such as eating, drinking and sex. Levine wrote an article regarding his study, entitled “Sex Differences in the Brain”. His study proved that the male and female brain produced different sex hormones. He found that males would engage “...in mounting and females were arching their backs and raising their butts to attract suitors.” Levine led a generation of neuroscientists into believing that this was the difference between the male and female brain. Up until approximately the last 10 years, there were not very many sex-specific facts regarding the brain, but time has changed making this belief seem like very primitive knowledge.
We have come made leaps and strides since 1966, scientific knowledge has found sex-specific differences vary in the most primitive of human functions, such as “... memory, emotion, vision, hearing, the processing of faces and the brain 's response to stress hormones.”, according to Cahill. Even our cognitive and behavioral areas are influenced by the sexes. This new knowledge and vast progress as Cahill states, “.. has been accelerated.... by the growing use of sophisticated noninvasive imaging techniques such as positron-emission tomography (PET) and functional magnetic resonance imaging (f MRI), which can peer into the brains of living subjects.”
By using this new technology, more anatomical differences than just size have been found. Jill M. Goldstein of Harvard Medical School and her colleagues found that parts of the frontal (cognitive) and limbic (emotional) cortex are bulkier than men 's. Yet, parts of the men 's parietal (space perception) cortex and amygdala (emotional arousal/adrenaline) are bulkier then women 's. These anatomical differences are relative to the importance of the way the brain works. The more significant the area, the more significant the influence.
Anatomical differences, have been found even at the cellular level. In the female brain, Sandra Witelson and her colleagues at McMaster University discovered that there is a greater neuron density in the frontal lobe, and in two out of the six layers of the temporal lobe cortex, which controls language processing and comprehension, one of the layers affected in the temporal lobe is the auditory cortex. Neuroscientists think that this density correlates with and/or the higher performance that women have on the verbal fluency tests, then men. Is this cognitive difference caused by nature or nurture? In animals, the denser areas Goldstein discovered had higher numbers of sex hormone receptors/steroids during development, helping with the organization and connections of the brain. According to Cahill, “such anatomical diversity may in large part by the activity of sex hormones that bathe the fetal brain ... suggests that at least some sex differences in cognitive function do not result from cultural influence or the hormonal changes associated with puberty – they are from birth.”
To study whether some sex gender specific roles were by nature or nurture, at the biological or social/cultural level, Melissa Hines of City University London and Gerianne M.
Alexander of Texas A & M University used our “cousins” the vervet monkeys. They conducted a study testing if the selection of gender based toys were chosen by culture influence or was it innate biology. The vervet monkeys were used because they are less likely to be swayed by the effects of human culture, giving us a better factual data to this nature or nurture study. They were given a selection of gender specific (boy/girl) and gender-neutral toys to play with. Male monkeys chose gender specific toys for boys and the female monkeys chose gender specific toys for girls. Both sexes spent equal time with the gender-neutral toys. Therefore, data showed these choices were instilled biologically(nature). These traits are genetically based and quite possibly and/or inherited through …show more content…
evolution.
Simon Baron-Cohen and his associates at the University of Cambridge chose a different approach to study nature or nurture differences between the sexes. Infants are known to be “people-centered”, so Baron-Cohen and his student Svetlana Lutchmaya studied one-year old children studying the length of time the toddlers spent looking at their mothers. They found that girls looked at their mothers at greater lengths over their male counterpart. Taking the study a step further they presented the children with a selection of films to watch, and found that the girls looked longer at a film watching a face longer and boys at a film of a car longer. Taking into consideration that there was a slight possibility of a bias due to the play time that the children may have had with adults, they took the study a step further. They visited a maternity ward. Taking their video camera, they decided to examine the preference of one day old babies. To keep the test unbiased, they were not given the sex of the infants prior. They created a mobile of the female student making it the same size and colors but scrambled the facial features. They then tested the infants on whether they would look longer at the student herself or the scrambled mobile of the student. When reviewing the tape after to draw their conclusion, they found that boys were more inclined to look at the mechanical object longer and the girls the live student. Therefore, the data proved that the theory that some cognitive sex differences are evident coming out of the womb.
Sex differences both chemically and constructionally impact our reaction to environment and stress stimuli.
We 've learned from Goldstein 's study and others that the amygdala is larger in males and the amygdala its actions have to do with emotional arousal and stress. In rats, the neurons of the males have more interconnections in males, thus, we would assume the same would be true in human males. Presumably these anatomical differences could be factors in how the sexes respond to stress stimuli differently. Katharina Braun and her co-workers at Otto von Guericke University in Magdeburg, Germany conducted a study into just that. For purposes of the study they used a litter of Degu (Octodon Degu) pups. According to Smiley 's Degu Pups, Degus are a brown-tweed, long-tailed rodent, similar in appearance to the gerbil, but the size of a small guinea pig, originating in South America and also known as the “Chilean Squirrel. These animals by nature are a social animal and live in large colonies. Separation of these animals cause quite an emotional reaction. Thus, for stimuli, they removed the litter of pups from their mother. According to Cahill, “they then measured the concentration of serotonin receptors in various brain regions. Serotonin is a neurotransmitter, or signal carrying molecule, that is key for mediating emotional behavior. (Prozac, for example, acts by increasing serotonin function.).” After they measured the serotonin, they stimulated the pups by letting them
hear the mother 's cries during the separation. In the males, this stressor increased the serotonin receptor concentration in the amygdala, but the amount decreased in the females. This study really is not a “great” study to cross-reference to humans, we must hypothesize the point, that if human infants were to undergo separation anxiety, it may cause similar affects and possibly increase male infants seratonin level, also. As Cahill points out this study does have its purpose, it and ones similar ones help us understand the prevalence of anxiety disorder being more prevalent in girls over boys.
Hippocampus, which through imaging we learn is larger in women than men, is crucial for memory storage and spatial coding. These may relate to the differences in the way men and women navigate. Men are more likely to use “dead reckoning”, estimating the distance and or location, and women are more likely to map things out using landmarks. Rats correlate the same style differences, per male and female, when mapping out their mazes. The differences in the hippocampus, has been found to go to the neuron level affecting the dendrites, in different ways. Janice M. Juraska and her associates at the University of Illinois placed rats in “enriched” environments, they filled their cages with toys and added other rodents, to promote social interaction, the results varied between male and female rats. In the females it enhanced the “bushiness” of their dendrite trees, which would mean an increase in neuronal connections, this production is as Taff would call it “the laying down of memories.” In males, though, it either had no effect or pruned the dendrite trees slightly.
Could this be they were more relaxed in this environment, as male rats are presumed to learn better under stress. Tracey J. Shors of Rutgers University and her collaborators found that a brief second long shock to the tail, enhances their learning and under this condition, it will increase the density of the dendrite trees in males, but impaired the females and pruned the density of their dendrite connections.
Based on the data found in th acute stress study and anxiety disorder study, in the face of chronic stress, though, we may assume that males would be more resilient, but the opposite is true. The rodents were disturbed by being restrained in a mesh cage for six hours, during a study by Cheryl D. Conrad and co-workers at Arizona State University. They then tested the results of the neurotoxins affect on killing the neurons in the hippocampus, a standard stress test, and found that male 's cells were more afflicted by the toxin than the females, which had no effect on the females vulnerability. There has not been any conclusive data as to why it does not effect females, the guess would be sex hormones. Tests like this one and similar test findings have suggested that in terms of long term brain damage, females are better suited for chronic stress and males in short term.
Cahill and colleagues have done some research of their own, into the effects of stress and laying down of memories – a process known as “activation of the amygdala”, stemming from animal research. Using human volunteers, one of his first experiments was to show them a series of violently graphic films, measuring their brain activity during, with a PET. Then three weeks later, they were given a quiz to see what they remembered. The general findings were the number of disturbing films they recalled correlated with the activity of the amygdala during the viewing. Yet, there was another finding that was unexpected, some studies of the amygdala the right hemisphere lit up (was used) and some the left. Upon closer analysis, it was found that men were using the right hemisphere and women were using the left. After that study, there have been three more studies to confirm the data – two from Cahill 's group and one by John Gabriel and Turhan Canli and their collaborators at Stanford – and all have confirmed the data in regards to how men and women lay down memories.
Cahill took his study a step further to understand why men and women were processing memories differently. He turned to a century-old theory, stating that the right hemisphere is biased toward processing the central aspects of a situation. He decided to curtail the amygdala 's activity by using a beta blocker drug called, Propranolo, that calms adrenaline and noradrenaline. Believing the drug should impair the amygdala and weaken the emotional recall of arousing memories, thus, hindering the ability for both male brain 's emotional recall and female brain 's attention to detail. Volunteers were shown a short slide show about a young boy having a terrible accident while walking with his mother. A week later, he tested the volunteers ' memories of the story. The outcome was that men had a harder time remembering the aspect/gist of the story, in example, that the boy had been ran over by a car, and women did not remember incidental details – that the boy was carrying a soccer ball.
More recent investigations, have found that we can detect the hemispheric differences in men and women almost immediately, when recording a reaction to emotional material. Showing volunteers unpleasant photographs, reaction time was within 300 milliseconds. Antonella Gasbarri and others at the University of L 'Aquila in Italy, this quick response time, turned a P300, is more exaggerated in men when recorded over the right hemisphere and more exaggerated in women over the left hemisphere. This shows us the sex related disparities begin within those 300 milliseconds, long before our conscience has a chance to interpret.
These last few studies Cahill has presented may pose complications for treating PTSD. A previous research study by Gustav Schelling and his associates at Ludwig Maximilian University in Germany established that the beta-blocker, propranolol, (used in Cahill 's study) could diminish some memory of traumatic situations when used as a part of the treatment plan, in an ICU. According to Cahill 's findings, beta-blockers are effective in reducing traumatic recollection of events in women but are useless in men. Thus, being a prime argument for why there needs to be more sex-related studies into care plans and treatments for men and women.
PTSD, is not the only sex-related mental disorder that needs to be studied further. Depression, generally more prominent in women, is mainly treated with a form of serotonin. Well, according to a PET study by Mirko Diksic and his colleagues at McGill University, serotonin production in men is 52% higher. So, in women serotonin may be the correct treatment, but it may be in effective in men, since it already prevalent.
In addiction, dopamine is the neurotransmitter in question – a chemical that gives off a feeling of pleasure associated with drug abuse. In a study by Jill B. Becker and her fellow investigators at the University of Michigan at Ann Arbor discovered that estrogen boosts the release of dopamine in brain regions that regulates drug-seeking behavior/cravings. The effects of dopamine in rats, with addiction made them pursue cocaine weeks after the last use. This susceptibility – particularly to stimulants (cocaine and amphetamine) – could be why women seem to become addicted quicker than men. There are certain brain abnormalities underlying schizophrenia that differ in men and women.
Ruben Gur, Raquel Gur and their colleagues at the University of Pennsylvania have spent years studying sex-related differences of the brains anatomy and function. In one of their investigations they found that women possess a significantly larger orbitofrontal-to-amygdala ratio (OAR) than men do. One could speculate that this is the reason women are able to better control their emotional reactions. In additional experiments, the balance is altered in schizophrenia, though not identically for men and women. In other words, women with schizophrenia have a decreased OAR relative to their peers, as may be expected but men with schizophrenia have an increased OAR. This may seem out of sorts but it does show it is different in men and women, the treatment probably needs to be more sex-related due to these variables.
In a comprehensive 2001 report, the National Academy of Sciences asserted that “sex matters. Sex, that is being male or female, is an important human variable that should be considered when designing and analyzing studies in all areas and at all levels of biomedical and health-related research.” As Cahill points out, we are still nowhere close to where we should be for gender specific medication. Neuroscientists are far from putting all the pieces together and understanding all the sex-related differences of our brains. The studies Cahill discusses in his article, “Her Brain, His Brain,” just give us a vague overview of the differences between the sex-specific brain functions that have been found. Cahill has correlated great data that these differences are found in almost every aspect of human behavior, all the way down to the neurons. It is not just a case of nurture but also, nature and evolution differences.
However, in the case of Lawrence Summers and his belief that women are inferior in math, physics and science due to the size of the brain is a primitive belief and has no spot in today 's times or science. It goes back to one of the first things we learn in Psychology class, do not make a statement unless you have data to back it. There are Neanderthals out there that may still be trying to push the belief to this day, but where is the data? In the case of Summers, upon further research and reading NOW 's press release regarding the situation, calling for his resignation, we learn more insight to his sexism. In the four years of Presidency at Harvard prior to this, there was a decline in tenure for women down to 4 out of 32 offers, in the School 's Faculty of Arts and Science.
References
Smiley 's Degu Spot. (N.D.). Retrieved from
HTTP://www.geocities.com/smileysdeguspot/generalinfo.html
Thalheimer, Jenny (2005) Now Calls for Resignation of Harvard University 's President. Retrieved from http://www.now.org/press/01-05/01-20-Harvard.html
Box, D. (2001) Brain Size and Intelligence. Retrieved from http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=neurosci.box.1833
Abstract
As Larry Cahill 's article “His Brain, Her Brain”, points out there has been data showing a vast “...array of structural, chemical and functional variations” between the sexes; but does size matter? Lawrence Summers, former President of Harvard, thought so. Men 's brains are 13% larger than women 's brains, but does that really make them more advanced in math, physics and science? There are other anatomical variations and some of these are found to influence the way male and female brains work. Scientists have spent decades studying the brain and trying to answer questions regarding brain function. Trying to answer what actions are nature or nurture. Why do men and women act so …show more content…
differently? There have been great strives in research, since Seymour Levine 's 1966 hormonal theory.
They are now closer than ever to understanding functions of the brain and sex-specific functions. Some of these new sex-specific findings are leading scientists to a new array of questions; such as, whether or not we need to take into account gender or run the risk of getting inaccurate data in trials and experiments. Are there better sex-specific treatments we could be using in medicine? Conditions like PTSD (Post-Traumatic Stress Disorder), depression, schizophrenia, etc. may have better treatment plans. To understand this, we must understand the roots of sex-specific studies into the brain. Cahill enlightens us on what we have discovered.
2 Critical Review No. 2: His Brain, Her Brain
Are men better at math, physics and science because of merely the size of their brains? Lawrence Summers, President of Harvard (at the time), caused quite a stir when he stated that men were. Does size really matter in these subjects? Yes, men 's brains are generally in whole 13% larger than women 's, that is a scientific fact. Nineteenth-century enthusiasm for brain size as a simple measure of human performance was championed by some remarkably astute scientists (including Darwin 's cousin Francis Galton and the French neurologist Paul Broca), as well as others whose motives and methods are now suspect. Broca, one of the great neurologists of his day and a gifted observer, not only thought that brain size reflected intelligence, but was of the opinion (as was just about every other nineteenth-century male scientist) that white European males had larger and better-developed brains than anyone else. but this is a new age, a time of new discoveries, new studies and scientific findings. New experiments and data, along with technological developments have brought us out of the dark age.
As Larry Cahill 's article “His Brain, Her Brain”, points out there has been data showing a vast “...array of structural, chemical and functional variations” between the sexes; but no data that these disparities hinder women 's ability to excel in any of these subjects. He does examine many of the findings between the two sexes, pointing out many variations and yes, there are anatomical differences that do influence the way male and female brains work but there is no proof or data to support Summers, structurally, anatomically, chemically and/or functionally.
Scientists have spent decades studying the brain and trying to answer questions regarding the brain. Trying to answer whether cognitive actions or behavior are traits of nature or nurture. Does the brain have sex-specific variances? There have been great strives Seymour Levine of Stanford University 's 1966 theory until now. Cahill enlightens us on the “new” sex-specific brain.
At first, it was believed some of the varying functions of the brain, between the sexes, were limited to only the region having to do with mating hormones. These hormones are produced in a small area at the base of the brain, called hypothalamus. The hypothalamus regulates our hormones and also, basic instincts, such as eating, drinking and sex. Levine wrote an article regarding his study, entitled “Sex Differences in the Brain”. His study proved that the male and female brain produced different sex hormones. He found that males would engage “...in mounting and females were arching their backs and raising their butts to attract suitors.” Levine led a generation of neuroscientists into believing that this was the difference between the male and female brain. Up until approximately the last 10 years, there were not very many sex-specific facts regarding the brain, but time has changed making this belief seem like very primitive knowledge.
We have come made leaps and strides since 1966, scientific knowledge has found sex-specific differences vary in the most primitive of human functions, such as “... memory, emotion, vision, hearing, the processing of faces and the brain 's response to stress hormones.”, according to Cahill. Even our cognitive and behavioral areas are influenced by the sexes. This new knowledge and vast progress as Cahill states, “.. has been accelerated.... by the growing use of sophisticated noninvasive imaging techniques such as positron-emission tomography (PET) and functional magnetic resonance imaging (f MRI), which can peer into the brains of living subjects.”
By using this new technology, more anatomical differences than just size have been found. Jill M. Goldstein of Harvard Medical School and her colleagues found that parts of the frontal (cognitive) and limbic (emotional) cortex are bulkier than men 's. Yet, parts of the men 's parietal (space perception) cortex and amygdala (emotional arousal/adrenaline) are bulkier then women 's. These anatomical differences are relative to the importance of the way the brain works. The more significant the area, the more significant the influence.
Anatomical differences, have been found even at the cellular level. In the female brain, Sandra Witelson and her colleagues at McMaster University discovered that there is a greater neuron density in the frontal lobe, and in two out of the six layers of the temporal lobe cortex, which controls language processing and comprehension, one of the layers affected in the temporal lobe is the auditory cortex. Neuroscientists think that this density correlates with and/or the higher performance that women have on the verbal fluency tests, then men. Is this cognitive difference caused by nature or nurture? In animals, the denser areas Goldstein discovered had higher numbers of sex hormone receptors/steroids during development, helping with the organization and connections of the brain. According to Cahill, “such anatomical diversity may in large part by the activity of sex hormones that bathe the fetal brain ... suggests that at least some sex differences in cognitive function do not result from cultural influence or the hormonal changes associated with puberty – they are from birth.”
To study whether some sex gender specific roles were by nature or nurture, at the biological or social/cultural level, Melissa Hines of City University London and Gerianne M.
Alexander of Texas A & M University used our “cousins” the vervet monkeys. They conducted a study testing if the selection of gender based toys were chosen by culture influence or was it innate biology. The vervet monkeys were used because they are less likely to be swayed by the effects of human culture, giving us a better factual data to this nature or nurture study. They were given a selection of gender specific (boy/girl) and gender-neutral toys to play with. Male monkeys chose gender specific toys for boys and the female monkeys chose gender specific toys for girls. Both sexes spent equal time with the gender-neutral toys. Therefore, data showed these choices were instilled biologically(nature). These traits are genetically based and quite possibly and/or inherited through …show more content…
evolution.
Simon Baron-Cohen and his associates at the University of Cambridge chose a different approach to study nature or nurture differences between the sexes. Infants are known to be “people-centered”, so Baron-Cohen and his student Svetlana Lutchmaya studied one-year old children studying the length of time the toddlers spent looking at their mothers. They found that girls looked at their mothers at greater lengths over their male counterpart. Taking the study a step further they presented the children with a selection of films to watch, and found that the girls looked longer at a film watching a face longer and boys at a film of a car longer. Taking into consideration that there was a slight possibility of a bias due to the play time that the children may have had with adults, they took the study a step further. They visited a maternity ward. Taking their video camera, they decided to examine the preference of one day old babies. To keep the test unbiased, they were not given the sex of the infants prior. They created a mobile of the female student making it the same size and colors but scrambled the facial features. They then tested the infants on whether they would look longer at the student herself or the scrambled mobile of the student. When reviewing the tape after to draw their conclusion, they found that boys were more inclined to look at the mechanical object longer and the girls the live student. Therefore, the data proved that the theory that some cognitive sex differences are evident coming out of the womb.
Sex differences both chemically and constructionally impact our reaction to environment and stress stimuli.
We 've learned from Goldstein 's study and others that the amygdala is larger in males and the amygdala its actions have to do with emotional arousal and stress. In rats, the neurons of the males have more interconnections in males, thus, we would assume the same would be true in human males. Presumably these anatomical differences could be factors in how the sexes respond to stress stimuli differently. Katharina Braun and her co-workers at Otto von Guericke University in Magdeburg, Germany conducted a study into just that. For purposes of the study they used a litter of Degu (Octodon Degu) pups. According to Smiley 's Degu Pups, Degus are a brown-tweed, long-tailed rodent, similar in appearance to the gerbil, but the size of a small guinea pig, originating in South America and also known as the “Chilean Squirrel. These animals by nature are a social animal and live in large colonies. Separation of these animals cause quite an emotional reaction. Thus, for stimuli, they removed the litter of pups from their mother. According to Cahill, “they then measured the concentration of serotonin receptors in various brain regions. Serotonin is a neurotransmitter, or signal carrying molecule, that is key for mediating emotional behavior. (Prozac, for example, acts by increasing serotonin function.).” After they measured the serotonin, they stimulated the pups by letting them
hear the mother 's cries during the separation. In the males, this stressor increased the serotonin receptor concentration in the amygdala, but the amount decreased in the females. This study really is not a “great” study to cross-reference to humans, we must hypothesize the point, that if human infants were to undergo separation anxiety, it may cause similar affects and possibly increase male infants seratonin level, also. As Cahill points out this study does have its purpose, it and ones similar ones help us understand the prevalence of anxiety disorder being more prevalent in girls over boys.
Hippocampus, which through imaging we learn is larger in women than men, is crucial for memory storage and spatial coding. These may relate to the differences in the way men and women navigate. Men are more likely to use “dead reckoning”, estimating the distance and or location, and women are more likely to map things out using landmarks. Rats correlate the same style differences, per male and female, when mapping out their mazes. The differences in the hippocampus, has been found to go to the neuron level affecting the dendrites, in different ways. Janice M. Juraska and her associates at the University of Illinois placed rats in “enriched” environments, they filled their cages with toys and added other rodents, to promote social interaction, the results varied between male and female rats. In the females it enhanced the “bushiness” of their dendrite trees, which would mean an increase in neuronal connections, this production is as Taff would call it “the laying down of memories.” In males, though, it either had no effect or pruned the dendrite trees slightly.
Could this be they were more relaxed in this environment, as male rats are presumed to learn better under stress. Tracey J. Shors of Rutgers University and her collaborators found that a brief second long shock to the tail, enhances their learning and under this condition, it will increase the density of the dendrite trees in males, but impaired the females and pruned the density of their dendrite connections.
Based on the data found in th acute stress study and anxiety disorder study, in the face of chronic stress, though, we may assume that males would be more resilient, but the opposite is true. The rodents were disturbed by being restrained in a mesh cage for six hours, during a study by Cheryl D. Conrad and co-workers at Arizona State University. They then tested the results of the neurotoxins affect on killing the neurons in the hippocampus, a standard stress test, and found that male 's cells were more afflicted by the toxin than the females, which had no effect on the females vulnerability. There has not been any conclusive data as to why it does not effect females, the guess would be sex hormones. Tests like this one and similar test findings have suggested that in terms of long term brain damage, females are better suited for chronic stress and males in short term.
Cahill and colleagues have done some research of their own, into the effects of stress and laying down of memories – a process known as “activation of the amygdala”, stemming from animal research. Using human volunteers, one of his first experiments was to show them a series of violently graphic films, measuring their brain activity during, with a PET. Then three weeks later, they were given a quiz to see what they remembered. The general findings were the number of disturbing films they recalled correlated with the activity of the amygdala during the viewing. Yet, there was another finding that was unexpected, some studies of the amygdala the right hemisphere lit up (was used) and some the left. Upon closer analysis, it was found that men were using the right hemisphere and women were using the left. After that study, there have been three more studies to confirm the data – two from Cahill 's group and one by John Gabriel and Turhan Canli and their collaborators at Stanford – and all have confirmed the data in regards to how men and women lay down memories.
Cahill took his study a step further to understand why men and women were processing memories differently. He turned to a century-old theory, stating that the right hemisphere is biased toward processing the central aspects of a situation. He decided to curtail the amygdala 's activity by using a beta blocker drug called, Propranolo, that calms adrenaline and noradrenaline. Believing the drug should impair the amygdala and weaken the emotional recall of arousing memories, thus, hindering the ability for both male brain 's emotional recall and female brain 's attention to detail. Volunteers were shown a short slide show about a young boy having a terrible accident while walking with his mother. A week later, he tested the volunteers ' memories of the story. The outcome was that men had a harder time remembering the aspect/gist of the story, in example, that the boy had been ran over by a car, and women did not remember incidental details – that the boy was carrying a soccer ball.
More recent investigations, have found that we can detect the hemispheric differences in men and women almost immediately, when recording a reaction to emotional material. Showing volunteers unpleasant photographs, reaction time was within 300 milliseconds. Antonella Gasbarri and others at the University of L 'Aquila in Italy, this quick response time, turned a P300, is more exaggerated in men when recorded over the right hemisphere and more exaggerated in women over the left hemisphere. This shows us the sex related disparities begin within those 300 milliseconds, long before our conscience has a chance to interpret.
These last few studies Cahill has presented may pose complications for treating PTSD. A previous research study by Gustav Schelling and his associates at Ludwig Maximilian University in Germany established that the beta-blocker, propranolol, (used in Cahill 's study) could diminish some memory of traumatic situations when used as a part of the treatment plan, in an ICU. According to Cahill 's findings, beta-blockers are effective in reducing traumatic recollection of events in women but are useless in men. Thus, being a prime argument for why there needs to be more sex-related studies into care plans and treatments for men and women.
PTSD, is not the only sex-related mental disorder that needs to be studied further. Depression, generally more prominent in women, is mainly treated with a form of serotonin. Well, according to a PET study by Mirko Diksic and his colleagues at McGill University, serotonin production in men is 52% higher. So, in women serotonin may be the correct treatment, but it may be in effective in men, since it already prevalent.
In addiction, dopamine is the neurotransmitter in question – a chemical that gives off a feeling of pleasure associated with drug abuse. In a study by Jill B. Becker and her fellow investigators at the University of Michigan at Ann Arbor discovered that estrogen boosts the release of dopamine in brain regions that regulates drug-seeking behavior/cravings. The effects of dopamine in rats, with addiction made them pursue cocaine weeks after the last use. This susceptibility – particularly to stimulants (cocaine and amphetamine) – could be why women seem to become addicted quicker than men. There are certain brain abnormalities underlying schizophrenia that differ in men and women.
Ruben Gur, Raquel Gur and their colleagues at the University of Pennsylvania have spent years studying sex-related differences of the brains anatomy and function. In one of their investigations they found that women possess a significantly larger orbitofrontal-to-amygdala ratio (OAR) than men do. One could speculate that this is the reason women are able to better control their emotional reactions. In additional experiments, the balance is altered in schizophrenia, though not identically for men and women. In other words, women with schizophrenia have a decreased OAR relative to their peers, as may be expected but men with schizophrenia have an increased OAR. This may seem out of sorts but it does show it is different in men and women, the treatment probably needs to be more sex-related due to these variables.
In a comprehensive 2001 report, the National Academy of Sciences asserted that “sex matters. Sex, that is being male or female, is an important human variable that should be considered when designing and analyzing studies in all areas and at all levels of biomedical and health-related research.” As Cahill points out, we are still nowhere close to where we should be for gender specific medication. Neuroscientists are far from putting all the pieces together and understanding all the sex-related differences of our brains. The studies Cahill discusses in his article, “Her Brain, His Brain,” just give us a vague overview of the differences between the sex-specific brain functions that have been found. Cahill has correlated great data that these differences are found in almost every aspect of human behavior, all the way down to the neurons. It is not just a case of nurture but also, nature and evolution differences.
However, in the case of Lawrence Summers and his belief that women are inferior in math, physics and science due to the size of the brain is a primitive belief and has no spot in today 's times or science. It goes back to one of the first things we learn in Psychology class, do not make a statement unless you have data to back it. There are Neanderthals out there that may still be trying to push the belief to this day, but where is the data? In the case of Summers, upon further research and reading NOW 's press release regarding the situation, calling for his resignation, we learn more insight to his sexism. In the four years of Presidency at Harvard prior to this, there was a decline in tenure for women down to 4 out of 32 offers, in the School 's Faculty of Arts and Science.
References
Smiley 's Degu Spot. (N.D.). Retrieved from
HTTP://www.geocities.com/smileysdeguspot/generalinfo.html
Thalheimer, Jenny (2005) Now Calls for Resignation of Harvard University 's President. Retrieved from http://www.now.org/press/01-05/01-20-Harvard.html
Box, D. (2001) Brain Size and Intelligence. Retrieved from http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=neurosci.box.1833