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The brain is separated into different regions, and different regions perform different tasks. Well, what are the differences between these regions on the cellular/systemic level. The brain is made up of neurons and other cells, but how come one part is used to process sound and another is used to process, say, smell? Are they like different computer circuit boards - using the same components but are wired differently?
And anyways, why did evolution not come up with a brain that uses the entire brain to process something, would that not be more efficient?
The wiring is different as you mentioned. However, perhaps the most important is the brain knows where it's input is coming from. The brain knows where each fibre innervates and thus can compile and present this data to our conscious mind. We show if we stimulate the brain directly, than we feel a sensation in the part of the body that portion of the brain is responsible for. Plasticity means our brain can change what feeds into where, this is most commonly where we learn a motor skill. If we play the piano for example the part of the cortex feeding to this area increases.
Another way is the type of chemical transmitter and receptor. Dopamine is primarily used for things that cause us pleasure for example. However dopamine can affect our movement if it is secreted in from the substantia nigra, as this feeds into the motor cortex. Furthermore, neurotransmitters can be excitatory or inhibitory and this is an analogue rather than binary signal. All of these fine tune, and the position at which they inhibit and the location and the feedback from which they obtain their signal all indicates from where the brain is getting the information or to what it is responding to.
In summary it is wiring, signalling and location. However the components are incredibly similar but it isn't the small differences that have a profound effect.
The brain is separated into different regions, and different regions perform different tasks
Not really. This kind of claims stem from the early brain research, where every area was thought to specialize in one particular task. Sure, some categorization is possible (e.g. where the visual input is mostly processed). However, your question is basically an argument that is false.
Just look for example the temporal lobes and compare how the sulcal and gyral areas differ with respect to information processing.
We don't know yet in detail how different cortical areas are wired up, so it's difficult to say to what extent the wiring differs. But the overall structure of different cortical areas is remarkably similar, in terms of the layers of cortex and their cellular components.
Certainly the structure of the input is very different between cortical areas, and cortex seems to take great care during development how that input is structured.
We don't know why cortex is parcellated the way it is. But connections within cortical areas devoted to a single "function" are much more prevalent than connections between cortical areas. This suggests two things: many connections are required between neurons processing similar information, which implies that those neurons should be close together, because wire is expensive in the brain (i.e. requires resources and takes up a lot of space); alternatively, maybe the information is easier to process if it's kept physically separated.
Brain differences in ADHD
Largest imaging study of ADHD to date identifies differences in five regions of the brain, with greatest differences seen in children rather than adults.
Attention-deficit hyperactivity disorder (ADHD) is associated with the delayed development of five brain regions and should be considered a brain disorder, according to a study published in The Lancet Psychiatry.
The study is the largest to look at the brain volumes of people with ADHD, involving more than 3,200 people. The authors say the findings could help improve understanding of the disorder, and might be important in challenging beliefs that ADHD is a label for difficult children or the result of poor parenting.
ADHD symptoms include inattention and/or hyperactivity and acting impulsively. The disorder affects more than one in 20 (5.3%) under-18 year olds, and two-thirds of those diagnosed continue to experience symptoms as adults.
Previous studies have linked differences in brain volume with the disorder, but small sample sizes mean results have been inconclusive. Areas thought to be involved in ADHD are located in the basal ganglia -- a part of the brain that controls emotion, voluntary movement and cognition -- and research has previously found that the caudate and putamen regions within the ganglia are smaller in people with ADHD.
The new international study measured differences in the brain structure of 1,713 people with a diagnosis of ADHD and 1,529 people without, all aged between four and 63 years old.
All 3,242 people had an MRI scan to measure their overall brain volume, and the size of seven regions of the brain that were thought to be linked to ADHD -- the pallidum, thalamus, caudate nucleus, putamen, nucleus accumbens, amygdala, and hippocampus. The researchers also noted whether those with ADHD had ever taken psychostimulant medication, for example Ritalin.
The study found that overall brain volume and five of the regional volumes were smaller in people with ADHD -- the caudate nucleus, putamen, nucleus accumbens, amygdala and hippocampus.
"These differences are very small -- in the range of a few percent -- so the unprecedented size of our study was crucial to help identify these. Similar differences in brain volume are also seen in other psychiatric disorders, especially major depressive disorder." said lead author Dr Martine Hoogman, Radboud University Medical Center, Nijmegen, The Netherlands.
The differences observed were most prominent in the brains of children with ADHD, but less obvious in adults with the disorder. Based on this, the researchers propose that ADHD is a disorder of the brain, and suggest that delays in the development of several brain regions are characteristic of ADHD.
Besides the caudate nucleus and putamen, for which previous studies have already shown links to ADHD, researchers were able to conclusively link the amygdala, nucleus accumbens and hippocampus to ADHD.
The researchers hypothesise that the amygdala is associated with ADHD through its role in regulating emotion, and the nucleus accumbens may be associated with the motivation and emotional problems in ADHD via its role in reward processing. The hippocampus' role in the disorder might act through its involvement in motivation and emotion.
At the time of their MRI scan, 455 people with ADHD were receiving psychostimulant medication, and looking back further, 637 had had the medication in their lifetime. The different volumes of the five brain regions involved in ADHD were present whether or not people had taken medication, suggesting the differences in brain volumes are not a result of psychostimulants.
"The results from our study confirm that people with ADHD have differences in their brain structure and therefore suggest that ADHD is a disorder of the brain," added Dr Hoogman. "We hope that this will help to reduce stigma that ADHD is 'just a label' for difficult children or caused by poor parenting. This is definitely not the case, and we hope that this work will contribute to a better understanding of the disorder."
While the study included large numbers of people of all ages, its design means that it cannot determine how ADHD develops throughout life. Therefore, longitudinal studies tracking people with ADHD from childhood to adulthood to see how brain differences change over time will be an important next step in the research.
Writing in a linked Comment Dr Jonathan Posner, Columbia University, USA, said: "It is the largest study of its kind and well powered to detect small effect sizes. Large sample sizes are particularly important in the study of ADHD because of the heterogeneity of the disorder both in etiology and clinical manifestation. This study represents an important contribution by providing robust evidence to support the notion of ADHD as a brain disorder with substantial effects on the volumes of subcortical nuclei. Future meta- and mega-analyses will be required to investigate medication effects as well as the developmental course of volumetric differences in ADHD."
Active Early Learning Shapes Adult Brain Structure, New Research Shows
In new research published in the Journal of Cognitive Neuroscience, low socioeconomic status infants were randomized to either five years of cognitively and linguistically stimulating center-based care or a comparison condition the intervention resulted in large and statistically significant changes in brain structure measured in midlife, particularly for male individuals.
A teacher guides a student through a task in this historical photo of the Abecedarian Project. Image credit: Virginia Tech.
How does early life experience shape the human brain? The question is surprisingly difficult to answer, as it concerns the causes, rather than merely the correlates, of individual differences in human development.
Studies of such differences are normally observational and thus silent on the subject of causality.
Animal studies, in contrast, have demonstrated causal influence of environmental stimulation on brain structure using random assignment to physical environments with low or high complexity.
However, they cannot tell us about the features of the environment that matter most for human development: linguistic and cognitive stimulation.
The role of the environment in shaping brain development is a central issue for neuroscience, and a significant open question concerns the impact of uniquely human features of the environment, namely, linguistic and cognitive stimulation.
Whereas a large animal literature shows that more complex cage environments lead to microscopic and macroscopic brain changes, including larger cortex, such manipulations provide an incomplete model for the environmental differences that may matter most in human development.
These include differences in complex forms of cognitive and linguistic experience.
“Our research shows a relationship between brain structure and five years of high-quality, educational and social experiences,” said Professor Craig Ramey, a researcher in the Fralin Biomedical Research Institute at the Virginia Polytechnic Institute and State University.
“We have demonstrated that in vulnerable children who received stimulating and emotionally supportive learning experiences, statistically significant changes in brain structure appear in middle age.”
“The results support the idea that early environment influences the brain structure of individuals growing up with multi-risk socioeconomic challenges,” added Dr. Martha Farah, director of the Center for Neuroscience and Society at the University of Pennsylvania.
“This has exciting implications for the basic science of brain development, as well as for theories of social stratification and social policy.”
The study involved participants of the Abecedarian Project, which was established in North Carolina in the early 1970s.
The project initially enrolled 112 predominantly African American infants from homes of very low SES (low income and maternal education) with multiple associated risk factors such as paternal absence, welfare receipt, and low parental IQ, but free of neurodevelopmental disorder.
One of the 112 infants later received a diagnosis of a congenital condition that was disqualifying based on the exclusionary criteria, resulting in 111 infants participating in the study.
Both the comparison and treatment groups received extra health care, nutrition, and family support services.
However, beginning at six weeks of age, the treatment group also received five years of high quality educational support, five days a week, 50 weeks a year.
During follow-up examinations, structural MRI scans were obtained from 47 of the Abecedarian sample, 29 from the early intervention group and 18 from the comparison group.
When scanned, the participants were in their late 30s to early 40s, offering the researchers a unique look at how childhood factors affect the adult brain.
Analyzing the scans, the authors looked at brain size as a whole, including the cortex, the brain’s outermost layer, as well as five regions selected for their expected connection to the intervention’s stimulation of children’s language and cognitive development.
Those included the left inferior frontal gyrus and left superior temporal gyrus, which may be relevant to language, and the right inferior frontal gyrus and bilateral anterior cingulate cortex, relevant to cognitive control.
A fifth, the bilateral hippocampus, was added because its volume is frequently associated with early life adversity and socioeconomic status.
The scientists determined that those in the early education treatment group had increased size of the whole brain, including the cortex. Several specific cortical regions also appeared larger.
They also noted the group intervention treatment results for the brain were substantially greater for males than for females.
The reasons for this are not known, and were surprising, since both the boys and girls showed generally comparable positive behavioral and educational effects from their early enriched education.
“When we launched this project in the 1970s, the field knew more about how to assess behavior than it knew about how to assess brain structure,” Professor Ramey said.
“Because of advances in neuroimaging technology and through strong interdisciplinary collaborations, we were able to measure structural features of the brain.”
“The prefrontal cortex and areas associated with language were definitely affected and to our knowledge, this is the first experimental evidence on a link between known early educational experiences and long-term changes in humans.”
“We believe that these findings warrant careful consideration and lend further support to the value of ensuring positive learning and social-emotional support for all children — particularly to improve outcomes for children who are vulnerable to inadequate stimulation and care in the early years of life.”
Martha J. Farah et al. 2021. Randomized Manipulation of Early Cognitive Experience Impacts Adult Brain Structure. Journal of Cognitive Neuroscience 33 (6): 1197-1209 doi: 10.1162/jocn_a_01709
Differences in Human and Neanderthal Brains Explain Human Exceptionalism
When I was a little kid, my mom went through an Agatha Christie phase. She was a huge fan of the murder mystery writer and she read all of Christie’s books.
Agatha Christie was caught up in a real-life mystery of her own when she disappeared for 10 days in December 1926 under highly suspicious circumstances. Her car was found near her home, close to the edge of a cliff. But, she was nowhere to be found. It looked as if she disappeared without a trace, without any explanation. Eleven days after her disappearance, she turned up in a hotel room registered under an alias.
Christie never offered an explanation for her disappearance. To this day, it remains an enduring mystery. Some think it was a callous publicity stunt. Some say she suffered a nervous breakdown. Others think she suffered from amnesia. Some people suggest more sinister reasons. Perhaps, she was suicidal. Or maybe she was trying to frame her husband and his mistress for her murder.
Perhaps we will never know.
Like Christie’s fictional detectives Hercule Poirot and Miss Marple, paleoanthropologists are every bit as eager to solve a mysterious disappearance of their own. They want to know why Neanderthals vanished from the face of the earth. And what role did human beings (Homo sapiens) play in the Neanderthal disappearance, if any? Did we kill off these creatures? Did we outcompete them or did Neanderthals just die off on their own?
Anthropologists have proposed various scenarios to account for the Neanderthals’ disappearance. Some paleoanthropologists think that differences in the cognitive capabilities of modern humans and Neanderthals help explain the creatures’ extinction. According to this model, superior reasoning abilities allowed humans to thrive while Neanderthals faced inevitable extinction. As a consequence, we replaced Neanderthals in the Middle East, Europe, and Asia when we first migrated to these parts of the world.
Innovative work by researchers from Japan offers support for this scenario. 1 Using a technique called computational neuroanatomy, researchers reconstructed the brain shape of Neanderthals and modern humans from the fossil record. In their study, the researchers used four Neanderthal specimens:
- Amud 1 (50,000 to 70,000 years in age)
- La Chapelle-aux Saints 1 (47,000 to 56,000 years in age)
- La Ferrassie 1 (43,000 to 45,000 years in age)
- Forbes’ Quarry 1 (no age dates)
They also worked with four Homo sapiens specimens:
- Qafzeh 9 (90,000 to 120,000 years in age)
- Skhūl 5 (100,000 to 135,000 years in age
- Mladeč 1 (35,000 years in age)
- Cro-Magnon 1 (32,000 years in age)
Researchers used computed tomography scans to construct virtual endocasts (cranial cavity casts) of the fossil brains. After generating endocasts, the team determined the 3D brain structure of the fossil specimens by deforming the 3D structure of the average human brain so that it fit into the fossil crania and conformed to the endocasts.
This technique appears to be valid, based on control studies carried out on chimpanzee and bonobo brains. Using computational neuroanatomy, researchers can deform a chimpanzee brain to accurately yield the bonobo brain, and vice versa.
Brain Differences, Cognitive Differences
The Japanese team learned that the chief difference between human and Neanderthal brains is the size and shape of the cerebellum. The cerebellar hemisphere is projected more toward the interior in the human brain than in the Neanderthal brain and the volume of the human cerebellum is larger. Researchers also noticed that the right side of the Neanderthal cerebellum is significantly smaller than the left side—a phenomenon called volumetric laterality. This discrepancy doesn’t exist in the human brain. Finally, the Japanese researchers observed that the parietal regions in the human brain were larger than those regions in Neanderthals’ brains.
Because of these brain differences, the researchers argue that humans were socially and cognitively more sophisticated than Neanderthals. Neuroscientists have discovered that the cerebellum helps motor functions and higher cognition by contributing to language function, working memory, thought, and social abilities. Hence, the researchers argue that the reduced size of the right cerebellar hemisphere in Neanderthals limits the connection to the prefrontal regions—a connection critical for language processing. Neuroscientists have also discovered that the parietal lobe plays a role in visuo-spatial imagery, episodic memory, self-related mental representations, coordination between self and external spaces, and sense of agency.
On the basis of this study, it seems that humans either outcompeted Neanderthals for limited resources—driving them to extinction—or simply were better suited to survive than Neanderthals because of superior mental capabilities. Or perhaps their demise occurred for more sinister reasons. Maybe we used our sophisticated reasoning skills to kill off these creatures.
Did Neanderthals Make Art, Music, Jewelry, etc.?
Recently, a flurry of reports has appeared in the scientific literature claiming that Neanderthals possessed the capacity for language and the ability to make art, music, and jewelry. Other studies claim that Neanderthals ritualistically buried their dead, mastered fire, and used plants medicinally. All of these claims rest on highly speculative interpretations of the archaeological record. In fact, other studies present evidence that refutes every one of these claims (see Resources).
Comparisons of human and Neanderthal brain morphology and size become increasingly important in the midst of this controversy. This recent study—along with previous work (go here and here)—indicates that Neanderthals did not have the brain architecture and, hence, cognitive capacity to communicate symbolically through language, art, music, and body ornamentation. Nor did they have the brain capacity to engage in complex social interactions. In short, Neanderthal brain anatomy does not support any interpretation of the archaeological record that attributes advanced cognitive abilities to these creatures.
While this study provides important clues about the disappearance of Neanderthals, we still don’t know why they went extinct. Nor do we know any of the mysterious details surrounding their demise as a species.
Perhaps we will never know.
But we do know that in terms of our cognitive and social capacities, human beings stand apart from Neanderthals and all other creatures. Human brain biology and behavior render us exceptional, one-of-a-kind, in ways consistent with the image of God.
Brain scans show distinctive patterns in people with generalized anxiety disorder in Stanford study
This image shows, in red, brain regions with stronger connections to the amygdala in patients with GAD, while the blue areas indicate weaker connectivity. The red corresponds to areas important for attention and may reflect the habitual use of cognitive strategies like worry and distraction in the anxiety patients. For a high-resolution version, click here.
Scrambled connections between the part of the brain that processes fear and emotion and other brain regions could be the hallmark of a common anxiety disorder, according to a new study from the Stanford University School of Medicine. The findings could help researchers identify biological differences between types of anxiety disorders as well as such disorders as depression.
The study published Dec. 7 in the Archives of General Psychiatry, examined the brains of people with generalized anxiety disorder, or GAD, a psychiatric condition in which patients spend their days in a haze of worry over everyday concerns. Researchers have known that the amygdala, a pair of almond-sized bundles of nerve fibers in the middle of the brain that help process emotion, memory and fear, are involved in anxiety disorders like GAD. But the Stanford study is the first to peer close enough to detect neural pathways going to and from subsections of this tiny brain region.
Such small-scale observations are important for understanding the brains of people with psychiatric disorders, said Duke University neuroscientist Kevin LaBar, PhD, who was not involved in the research. “If we want to distinguish GAD from other anxiety disorders, we might have to look at these subregions instead of the general signal from this area,” he said. “It’s methodologically really impressive.”
To get close enough to discern one region of the amygdala from another, Stanford psychiatry resident Amit Etkin, MD, PhD, and his colleagues focused on “regions of interest” defined by detailed anatomical studies of human brains. They recruited 16 people with GAD and 17 psychologically healthy participants and scanned their brains using functional magnetic resonance imaging, which measures blood-flow fluctuations caused by changes in activity in different regions of the brain. Each person spent eight minutes in the fMRI scanner, letting their minds wander.
The researchers analyzed the resulting data to determine which areas were connected — that is, which regions were likely to activate in tandem. They first looked at one subregion, the basolateral amygdala, which sits at the base of the amygdala. In healthy participants, they found that the subregion was linked to the occipital lobe at the rear of the brain, the temporal lobes beneath the ears and the prefrontal cortex just behind the forehead. These regions are associated with visual and auditory processing, as well as with memory and high-level emotional and cognitive functions.
The other subregion, known as the centromedial amygdala and found at the top of the amygdala, was associated with subcortical, or deeper, areas of the brain. These connections included the thalamus, which controls information flow throughout the brain and helps regulate alertness from its perch in the midbrain the brain stem, which regulates heart rate, breathing and release of neurotransmitters like serotonin and dopamine and the densely wrinkled cerebellum, which sits behind the brain stem and controls motor coordination. The associations corroborated what anatomical studies in animals have found, said Etkin, the lead author of the study. The team also analyzed resting fMRI data from 31 more healthy people and found similar results.
But in people with GAD, the scans revealed another pattern. The two regions still sent emissaries to their separate targets, but the lines of communication were muddled.
“The basolateral amygdala was less connected with all of its targets and more connected with centromedial targets,” Etkin said. “And the centromedial was less connected with its normal targets and more connected with the basolateral targets.”
The researchers also found that both amygdala regions had less connectivity to the region of the brain responsible for determining the importance of stimuli. This could mean that people with the disorder have a harder time discerning truly worrisome situations from mild annoyances. At the same time, the amygdala was more connected to a cortical executive-control network previously found to exert cognitive control over emotion.
The cognitive control connection might explain why GAD is characterized by obsessive worry, Etkin said. People with the disorder feel overwhelmed by emotion and don’t believe they can feel sad or upset without coming completely undone. So, in an attempt to avoid facing their unpleasant feelings, they distract themselves by fretting. Such overthinking may work in the short term but becomes problematic over time.
Researchers can’t say for sure whether the connectivity abnormalities came first or whether excessive worrying shaped the brain by reinforcing particular neural pathways. Still, the patterns uncovered by neurological scans could one day help psychiatrists diagnose and treat the disease.
“This is a nice example of neurology and psychiatry joining forces,” said Michael Greicius, MD, assistant professor of neurology and neurological sciences at Stanford and senior author of the paper.
The next step, said Etkin, is to study patients with other anxiety disorders and with depression. That will allow researchers to see if patterns of amygdala connectivity differ between disorders. If they do, brain scans could one day become additional diagnostic tools for disorders with symptoms that often overlap.
The research was funded by the National Institutes of Health and the residency-research program of the Veterans Affairs Palo Alto Health Care System. Co-authors of the paper are research assistant Katherine Keller Prater Alan Schatzberg, MD, the Kenneth T. Norris, Jr. Professor and chair of psychiatry and behavioral sciences and Vinod Menon, PhD, associate professor of psychiatry and behavioral sciences.
What is Cerebrum
Cerebrum refers to the most prominent and the most anterior part of the vertebrate brain, which consists of two hemispheres. The two hemispheres are separated by a fissure. Corpus callosum is the large neuron bundle that connects the two hemispheres. The two types of nerve tissues in the cerebrum are gray matter and white matter. The gray matter occurs on the outside of the cerebrum and is called the cerebral cortex. It contains cell bodies and dendrites of the neurons in the cerebrum. The white matter is found beneath the gray matter and contains nerve fibers. Cerebrum accounts for 4/5 of the total weight of the brain. The two hemispheres of the cerebrum are shown in the image 1.
Figure 1: Hemispheres of Cerebrum (red)
Each hemisphere further divides into four lobes: frontal lobe, parietal lobe, temporal lobe, and occipital lobe. The three fissures that separate the four lobes from each other are the central fissure, Sylvian fissure, and the parieto-occipital Sylvian fissure. The main function of the cerebrum is to control voluntary movements of the body cooperatively with the cerebellum. The four lobes of a cerebral hemisphere are shown in figure 2.
Figure 2: Lobes of a Cerebral Hemisphere
The front lobe is responsible for planning, awareness, organization, speech, and emotional expressions other than voluntary movements. The temporal lobe contains the auditory cortex. The parietal lobe contains a motor cortex, involved in the somatosensory perceptions. In the somatosensory perception, the body responds to the senses obtained from visual, acoustic, and memory functions. The occipital lobe contains the visual cortex. Generally, the right side of the brain controls the left side of the body while the left side of the brain controls the right side of the body. The left cerebral hemisphere is responsible for writing, language, speech, and linear sequential processing. However, the right cerebral hemisphere is responsible for music, drawing, emotions, visual-spatial activities, and parallel processing.
The hardwired difference between male and female brains could explain why men are ➾tter at map reading'
A pioneering study has shown for the first time that the brains of men and women are wired up differently which could explain some of the stereotypical differences in male and female behaviour, scientists have said.
Researchers found that many of the connections in a typical male brain run between the front and the back of the same side of the brain, whereas in women the connections are more likely to run from side to side between the left and right hemispheres of the brain.
This difference in the way the nerve connections in the brain are “hardwired” occurs during adolescence when many of the secondary sexual characteristics such as facial hair in men and breasts in women develop under the influence of sex hormones, the study found.
The researchers believe the physical differences between the two sexes in the way the brain is hardwired could play an important role in understanding why men are in general better at spatial tasks involving muscle control while women are better at verbal tasks involving memory and intuition.
Psychological testing has consistently indicated a significant difference between the sexes in the ability to perform various mental tasks, with men outperforming women in some tests and women outperforming men in others. Now there seems to be a physical explanation, scientists said.
“These maps show us a stark difference - and complementarity - in the architecture of the human brain that helps to provide a potential neural basis as to why men excel at certain tasks, and women at others,” said Ragini Verma, professor of radiology at the University of Pennsylvania in Philadelphia.
“What we've identified is that, when looked at in groups, there are connections in the brain that are hardwired differently in men and women. Functional tests have already shown than when they carry out certain tasks, men and women engage different parts of the brain,” Professor Verma said.
The research was carried out on 949 individuals - 521 females and 428 males - aged between 8 and 22. The brain differences between the sexes only became apparent after adolescence, the study found.
A special brain-scanning technique called diffusion tensor imaging, which can measure the flow of water along a nerve pathway, established the level of connectivity between nearly 100 regions of the brain, creating a neural map of the brain called the “connectome”, Professor Verma said.
“It tells you whether one region of the brain is physically connected to another part of the brain and you can get significant differences between two populations,” Professor Verma said.
“In women most of the connections go between left and right across the two hemispheres while in men most of the connections go between the front and the back of the brain,” she said.
Because the female connections link the left hemisphere, which is associated with logical thinking, with the right, which is linked with intuition, this could help to explain why women tend to do better than men at intuitive tasks, she added.
“Intuition is thinking without thinking. It's what people call gut feelings. Women tend to be better than men at these kinds of skill which are linked with being good mothers,” Professor Verma said.
Many previous psychological studies have revealed significant differences between the sexes in the ability to perform various cognitive tests.
Men tend to outperform women involving spatial tasks and motor skills - such as map reading - while women tend to better in memory tests, such as remembering words and faces, and social cognition tests, which try to measure empathy and “emotional intelligence”.
A separate study published last month found that the genes expressed in the human brain did so differently in men and women. Post-mortem tests on the brain and spinal cord of 100 individuals showed significant genetic differences between the sexes, which could account for the observed gender differences in neurological disorders, such as autism, according to scientists from University College London.
For instance, one theory of autism, which is affects about five times as many boys as girls, is that it is a manifestation of the “extreme male brain”, which is denoted by a failure to be able to show empathy towards others.
The latest study, published in the Proceedings of the National Academy of Sciences, showed that the differences in the male and female “connectomes” develop during at the same age of onset of the gender differences seen in psychological tests.
The only part of the brain where right-left connectivity was greater in men than in women was in the cerebellum, an evolutionary ancient part of the brain that is linked with motor control.
“It's quite striking how complementary the brains of women and men really are,” said Rubin Gur of Pennsylvania University, a co-author of the study.
“Detailed connectome maps of the brain will not only help us better understand the differences between how men and women think, but it will also give us more insight into the roots of neurological disorders, which are often sex related,” Dr Gur said.
Brain Differences Between Genders
It’s no secret that boys and girls are different—very different. The differences between genders, however, extend beyond what the eye can see. Research reveals major distinguishers between male and female brains.
Scientists generally study four primary areas of difference in male and female brains: processing, chemistry, structure, and activity. The differences between male and female brains in these areas show up all over the world, but scientists also have discovered exceptions to every so-called gender rule. You may know some boys who are very sensitive, immensely talkative about feelings, and just generally don’t seem to fit the “boy” way of doing things. As with all gender differences, no one way of doing things is better or worse. The differences listed below are simply generalized differences in typical brain functioning, and it is important to remember that all differences have advantages and disadvantages.
Male brains utilize nearly seven times more gray matter for activity while female brains utilize nearly ten times more white matter. What does this mean?
Gray matter areas of the brain are localized. They are information- and action-processing centers in specific splotches in a specific area of the brain. This can translate to a kind of tunnel vision when they are doing something. Once they are deeply engaged in a task or game, they may not demonstrate much sensitivity to other people or their surroundings.
White matter is the networking grid that connects the brain’s gray matter and other processing centers with one another. This profound brain-processing difference is probably one reason you may have noticed that girls tend to more quickly transition between tasks than boys do. The gray-white matter difference may explain why, in adulthood, females are great multi-taskers, while men excel in highly task-focused projects.
Male and female brains process the same neurochemicals but to different degrees and through gender-specific body-brain connections. Some dominant neurochemicals are serotonin, which, among other things, helps us sit still testosterone, our sex and aggression chemical estrogen, a female growth and reproductive chemical and oxytocin, a bonding-relationship chemical.
In part, because of differences in processing these chemicals, males on average tend to be less inclined to sit still for as long as females and tend to be more physically impulsive and aggressive. Additionally, males process less of the bonding chemical oxytocin than females. Overall, a major takeaway of chemistry differences is to realize that our boys at times need different strategies for stress release than our girls.
A number of structural elements in the human brain differ between males and females. “Structural” refers to actual parts of the brain and the way they are built, including their size and/or mass.
Females often have a larger hippocampus, our human memory center. Females also often have a higher density of neural connections into the hippocampus. As a result, girls and women tend to input or absorb more sensorial and emotive information than males do. By “sensorial” we mean information to and from all five senses. If you note your observations over the next months of boys and girls and women and men, you will find that females tend to sense a lot more of what is going on around them throughout the day, and they retain that sensorial information more than do men.
Additionally, before boys or girls are born, their brains developed with different hemispheric divisions of labor. The right and left hemispheres of the male and female brains are not set up exactly the same way. For instance, females tend to have verbal centers on both sides of the brain, while males tend to have verbal centers on only the left hemisphere. This is a significant difference. Girls tend to use more words when discussing or describing incidence, story, person, object, feeling, or place. Males not only have fewer verbal centers in general but also, often, have less connectivity between their word centers and their memories or feelings. When it comes to discussing feelings and emotions and senses together, girls tend to have an advantage, and they tend to have more interest in talking about these things.
Blood Flow and Brain Activity
While we are on the subject of emotional processing, another difference worth looking closely at is the activity difference between male and female brains. The female brain, in part thanks to far more natural blood flow throughout the brain at any given moment (more white matter processing), and because of a higher degree of blood flow in a concentration part of the brain called the cingulate gyrus, will often ruminate on and revisit emotional memories more than the male brain.
Males, in general, are designed a bit differently. Males tend, after reflecting more briefly on an emotive memory, to analyze it somewhat, then move onto the next task. During this process, they may also choose to change course and do something active and unrelated to feelings rather than analyze their feelings at all. Thus, observers may mistakenly believe that boys avoid feelings in comparison to girls or move to problem-solving too quickly.
These four, natural design differences listed above are just a sample of how males and females think differently. Scientists have discovered approximately 100 gender differences in the brain, and the importance of these differences cannot be overstated. Understanding gender differences from a neurological perspective not only opens the door to greater appreciation of the different genders, it also calls into question how we parent, educate, and support our children from a young age.
Asperger's and Autism: Brain Differences Found
Children with Asperger's syndrome show patterns of brain connectivity distinct from those of children with autism, according to a new study. The findings suggest the two conditions, which are now in one category in the new psychiatry diagnostic manual, may be biologically different.
The researchers used electroencephalography (EEG) recordings to measure the amount of signaling occurring between brain areas in children. They had previously used this measure of brain connectivity to develop a test that could distinguish between children with autism and typically-developing children.
"We looked at a group of 26 children with Asperger's, to see whether measures of brain connectivity would indicate they're part of autism group, or they stood separately," said study researcher Dr. Frank Duffy, a neurologist at Boston's Children Hospital. The study also included more than 400 children with autism, and about 550 typically-developing children, who served as controls.
At first, the test showed that children with Asperger's and those with autism were similar: both showed weaker connections, compared with typically-developing children, in a region of the brain's left hemisphere called the arcuate fasciculus, which is involved in language.
However, when looking at connectivity between other parts of the brain, the researchers saw differences. Connections between several regions in the left hemisphere were stronger in children with Asperger's than in both children with autism and typically-developing children.
The results suggest the conditions are related, but there are physiological differences in brain connectivity that distinguish children with Asperger's from those with autism, according to the study published Wednesday (July 31) in the journal BMC Medicine.
"The findings are exciting, and the methods are sophisticated," said Dr. James McPartland, a professor of child psychiatry at Yale University, who was not involved in the study. Although the study included a reasonable number of children, like any new finding, the research needs to be replicated in future studies, McPartland said.
People with Asperger&rsquos syndrome experience difficulties with social interaction, and can display unusual behaviors, such as repeating the same action or being excessively attached to performing certain routines. These symptoms overlap with those of autism disorder, however, children with Asperger's tend to show language and cognitive development that is closer to that of typically-developing children, compared with children with autism.
Recently, the American Psychiatric Association decided to eliminate Asperger's syndromefrom the newest revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM 5) and instead put it alongside autism under an umbrella term, autism spectrum disorders (ASD).
The APA's decision raised voices of concern from several places. Parents worried that their children with Asperger's might not receive the special training they need, and experts said it was premature to combine the two conditions under one groupwhen it cannot be ruled out that there are biological differences.
"At present, it is hard to know whether [the new findings] reflect a core, intrinsic difference between Asperger's and autism, or whether it is a reflection of developing with different characteristics," McPartland said.
Duffy said the new findings fit with the notion that autism and Asperger's syndrome are similar in some respects for example, both have difficulty getting along with other people.
However, stronger connectivity among the left hemisphere brain areas in children with Asperger's may be what makes people with Asperger's special in terms of their personalities and abilities, Duffy said.
"It's essential to separate these two groups, because they need different education and training and opportunity," he said. Editor's note: This story was updated on Monday Aug. 5 to refer to the control children in the study as "typically-developing."