About the Brain, Brain Based Learning, and Brain Development
About the BRAIN - #Multitasking
Myth #neural pathways
#spatial abilities #Multiple Intelligence # standards PAGE 2
The human brain contains between one thousand trillion and one million trillion synapses.
Sonogenetics: Sound waves
to activate brain cells in a worm VIDEO
For the first time, scientists have directly controlled brain cells using sound waves, in a tiny laboratory worm. They used ultrasound to trigger activity in specific neurons, causing the worms to change direction. As well as requiring a particular gene to be expressed in the brain cells, the technique bathes the animals in tiny bubbles to amplify the sound waves. These complications temper the technique's promise for controlling brain activity in a non-invasive way.
MEMORY: FROM THE BEGINNING
Most adults can't recall events that took place before they were 3 or 4 years old - a phenomenon called childhood amnesia. While some people can remember what happened at an earlier age, the veracity of their memories is often questioned. Now a new longitudinal study has found that events experienced by children as young as 2 can be recalled after long delays. "Our results are consistent with theories that suggest that basic capacity for remembering our own experiences may be in place by 2 years of age," according to Fiona Jack, postdoctoral fellow at the University of Otago, who led the study. "The study has implications in clinical and legal settings, where it is often important to know how likely it is that a particular memory of an early experience is in fact genuine." medicalnewstoday.com/releases/239690.php
consolidates memory with three-step brainwave
Our long-term memory is consolidated when we sleep. Short-term memory traces in the hippocampus, an area deep in the brain, are then relocated to more outer parts of the brain. An international team of neuroscientists now shows how a three-step brain oscillation plays an important part in that process.
Oscillations: waves of brain activity.
'Non-rapid eye movement (NREM) sleep is responsible for the memory consolidation during our sleep', Bonnefond explains. 'NREM is known for its very slow oscillations (SOs). Other types of oscillations are hidden inside these SOs. We discovered that three types of oscillations are nested inside each other in the hippocampus and have a joint function.'
Congressman Beats Watson
How a New Jersey Congressman beat I.B.M.'s question-answering supercomputer Watson at Jeopardy!
Rush D. Holt Jr., beat I.B.M.'s supercomputer, Watson, in a round of Jeopardy! I.B.M.'s Watson may have pummeled Jeopardy! champions Ken Jennings and Brad Rutter last month, but last week, a New Jersey Congressman beat the question-and-answer supercomputer. To be sure, it was no ordinary politician. Representative Rush D. Holt Jr., a New Jersey Democrat, is a physicist who spent the nine years before he won his first congressional race in 1998 as the assistant director of the plasma physics laboratory at Princeton University. Back in the 1970s, Mr. Holt recalled in an interview last Thursday, he tried his hand at Jeopardy!, and came away a five-time winner. He said he participated in the event in Washington, organized by I.B.M., to underscore the importance of government research funding and science education — and for the sheer cerebral sport of taking on Watson.
BUILDING A BRAIN
Building a Brain - 31
Videos Leading doctors and scientists discuss biology, behavior, and the brain. Monthly episode will examine
different subjects of the brain, including perception, social interaction, aging and creativity.
The first neurons, called "predecessors," are in place 31 days after fertilization. This is much earlier than previously thought and well before development of arms, legs or eyes. These neurons, precede all other known cell types of the developing cortex. "These precocious predecessor neurons might be important in the cascade of developmental events leading to the formation of the human cerebral cortex.1
Baby's dancing brain craves words, touch An infant stares at mom's face, not a trace of understanding in the still-focusing eyes. And yet behind that wide-eyed gaze and soft cap of bone, an electrical storm is taking place.
Build a Brain
--->>> PAGE 2
* Multitasking Myth Busted!
* Singing Familiar Songs is Found to Use Spatial Abilities
* Multiple Intelligences
- Neural Pathways - How the Body Knows?
* The Problem with Schools
It's nature, then nurture.
Genes provide each brain's basic building materials. The environment builds it through trillions of brain-cell connections made by sight, sound, smell, touch and movement. Positive experiences enhance brain connections, and negative experiences damage them.
Words work wonders.
Babies whose mothers and fathers talk to them routinely more often have larger vocabularies and tend to learn to read sooner and better.
Children who spend too much time in playpens and not enough on jungle gyms don't develop the motor cortex area of the brain and, as a result, show poor school readiness.
Piano instruction in particular can enhance the brain's ability to visualize ratios, fractions and proportions, and thus to learn math and logic.
Depriving an infant of loving talk and touch releases steroids that damage the brain's hippocampus, which controls its stress-response systems, and can lead to serious cognitive, emotional and social problems.
Chronic stress such as poverty, abuse or violence can impair the development of the amygdala, an almond-shaped area deep in the brain that houses emotion and memory. It also can confuse chemicals that moderate impulsive behavior, fear and aggression.
First Years of Life brain-imaging technologies
Deep inside the 1-pound infant brain, millions of wispy circuits are
zapping and firing, paving electrical roads and bridges that will carry the heavy traffic of learning,
questioning and creating throughout life.
The first five years of life are a crucial period for learning - a short but spectacular window of time when experiences such as a whisper, a hug and a bedtime lullaby can change the architecture of the developing brain. "We now have concrete images of the way the brain is hooked up early in life, and it is truly a remarkable period like no other in life," said Dr. Harry Chugani, a neuroscientist at the Children's Hospital of Michigan in Detroit. But interacting in these key years is far more than child's play, and the deprivation of talking, responding, smiling and playing in a child's life can forever change the course of that life cognitively, educationally and emotionally, scientists say. Long before the school years, the groundwork for how well a child will succeed and thrive is already being laid. "There is so much at play - genetics, nutrition, peers - nothing is set in stone," said Dr. Pat Kuhl, co-director of the University of Washington's Center for Mind, Brain & Learning.
The extraordinary development of the human brain begins a few weeks after conception.
Neurons - the brain cells that store and send information - begin multiplying at 50,000 per second, a frenzy
that continues throughout gestation. From that point on, environment begins to play its starring role in the
way the brain is wired for emotion, behavior and learning. Neurons send signals to other neurons through
axons, a thin fiber that relays electrical messages. Once an axon finds its target cell, it develops
dendrites, or branches, which receive a wide variety of information from other brain cells. The more
a nerve cell has, the better and quicker it is at learning. At birth, the infant brain has few of these
branches. Its neurons look like saplings. Adult neurons resemble trees with hundreds of branches formed
through experience and learning. "A well-stimulated child's brain - and an adult's, for that
matter - is visibly different under the microscope," said Dr. Lise Eliot, a neuroscientist with the
Chicago Medical School.
"A well-connected brain is a forest of dendrites," Eliot said. "In severely neglected children, those dendrite branches are not as dense, which means the quality of connections and the ability to learn is affected." Young brains work at warp speed. An infant's brain can form new learning connections at a rate of 3 billion per second. A child's brain uses twice as much glucose, the brain's fuel, as that of a chess master plotting three moves in advance.
How fast brain signals travel along these dendrites depends on how well their axons are coated with myelin, a fatty coating similar to plastic insulation around an electrical wire.
Myelin sheaths enable brain signals to travel 100 times faster. Babies are born with few myelinated axons. That's one reason infants can't see well and can't do much with their hands other than grasping and batting at objects. As children get older, different areas of the brain become myelinated on a genetically determined timetable. These periods of mylenization are critical periods for learning. For instance, the first axons to be myelinated in the language area of the brain are those that enable language comprehension. Six months later, myelination extends to the language-production area. Children who are malnourished, especially during these critical periods, have less myelination. This can explain learning problems like being a slow reader, Eliot said. Myelination continues well into the teenage years, primarily in the frontal lobe where decision making and rational capacity develop.
The wonders of a child's brain are not without limits.
Brief and early phases during development open parts of the brain that control vision and language to stimulation, then close forever. Experiments performed on kittens in which one eye is sewn shut reveal that the closed eye remains nonfunctional even after the stitches are removed, for example.
By 6 months of age, infants develop a map in the auditory cortex of the phonetic sounds in the native language their mother or caretaker speaks.
By 12 months, infants lose the ability to discriminate between sounds that are not made in their
native language. While subtle phonetic distinctions might be lost in the first year,
children have the ability to learn a second, third and fourth language quickly until about age 10.
After that, the brain starts discarding the excess language learning connections. After 10, learning a foreign language is still possible but more difficult.
This pruning of unused or unneeded neuron connections is necessary for thinking clearly, making fast associations, reacting to threats and solving problems. But the pruning process also can work against the growing child, especially if connections that could have proved useful later in life are killed because of lack of use.Only those connections that are reinforced over and over again will remain.
Cortex Matures Faster in Youth with Highest IQ
March 29, 2006 NIMH Child Psychiatry Branch
[Youth with superior IQ are distinguished by how fast the thinking part of their brains thickens
thins as they grow up...]
[ ...(MRI) scans showed that their brain's outer mantle, or cortex, thickens more rapidly during childhood, reaching its peak later than in their peers - perhaps reflecting a longer developmental window for high-level thinking circuitry. It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations.]
["Studies of brains have taught us that people with higher IQs do not have larger brains. Thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops," said NIH Director Elias A. Zerhouni, M.D.]
[The resulting scans were divided into three equal groups and analyzed based on IQ test scores: superior (121-145), high (109-120), and average (83-108).
The researchers found that the relationship between cortex thickness and IQ varied with age,
particularly in the prefrontal cortex, seat of abstract reasoning, planning, and other
functions. The smartest 7-year-olds tended to start out with a relatively thinner cortex that
thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially
thicker cortex peaked by age 8, with gradual thinning thereafter. Those in the high range showed an
intermediate trajectory (see below). While the cortex was thinning in all groups by the teen years, the
superior group showed the highest rates of change.
["Brainy children are not cleverer solely by virtue of having more or less gray matter at any one age," explained Rapoport. "Rather, IQ is related to the dynamics of cortex maturation."]
[... levels of activation in prefrontal areas correlates with IQ, note the researchers. They suggest that the prolonged thickening of prefrontal cortex in children with superior IQs might reflect an "extended critical period for development of high-level cognitive circuits." Although it's not known for certain what underlies the thinning phase, evidence suggests it likely reflects "use-it-or-lose-it" pruning of brain cells, neurons, and their connections as the brain matures and becomes more efficient during the teen years.]
"People with very agile minds tend to have a very agile cortex," said Shaw. The NIMH researchers are following-up with a search for gene variants that might be linked to the newly discovered trajectories. However, Shaw notes mounting evidence suggesting that the effects of genes often depends on interactions with environmental events, so the determinants of intelligence will likely prove to be a very complex mix of nature and nurture.
High-IQ kids navigate notable neural shifts
[ . . .The scientists propose that distinctive brain growth in superior-IQ youth reflects prolonged development of neural circuits that contribute to reasoning, planning, and other facets of analytical thinking.]
[ "Cortical thickness at any one age tells you next to nothing about intelligence," Shaw says. "What's important is that cortical development occurs differently in extremely clever kids, possibly as a result of particularly efficient sculpting of the brain."]
School Systems Aggravate Differences In Natural Ability? June 2006
Why doesn't 12 years of schooling raise the performance of kids who start out behind? Can you really tell which toddler is destined for Caltech?
For as long as there has been a science of intelligence (roughly a century), prevailing opinion has held that children's mental abilities are highly malleable, or "unstable." But according to new studies, for the most part people's mental abilities relative to others change very little from childhood through adulthood. Relative intelligence seems as resistant to change as relative nose sizes.
SOME blind people have the remarkable ability to navigate physical obstaclesMovie Camera without consciously perceiving them (see video, above). It now looks like they have their lateral geniculate nucleus (LGN) - part of the thalamus in the middle of the brain - to thank for this "blindsight". That's according to a team at the US National Institute of Mental Health in Bethesda, Maryland. They used macaques in which the primary visual cortex had been destroyed. The monkeys' eye-focusing movements revealed that they were "seeing" images shown at the periphery of their visual field, but only if their LGN was intact (Nature, DOI: 10.1038/nature09179).
Determine the Distribution of Intellectual Ability
One of the more striking findings comes from the longest follow-up study ever conducted in this field.
On June 1, 1932, Scotland had all children born in 1921 and attending school -- 87,498 11-year-olds -- take a 75-question test on analogies, reading, arithmetic and the like. The goal was to determine the distribution of intellectual ability. In 1998, scientists at the Universities of Edinburgh and Aberdeen tracked down 101 of those students, then 77 years old, and administered the same test.
The correlation between scores 66 years apart was a striking .73. (A correlation of 1 would mean no change in rankings; a correlation of .73 is very high.) There is "remarkable stability in individual differences in human intelligence" from childhood to old age, the scientists concluded in a 2000 paper.
In the U.S., two long-running studies also show the durability of relative intelligence. The Early Childhood Longitudinal Study, launched in 1998, tested 22,782 children entering kindergarten. As in the Scottish study, individual differences in mental ability were clear and persistent. In math and reading, when the children were sorted into three groups by ability, ranking stayed mostly the same from kindergarten to the end of the first and third grades. Some gaps actually widened.
The National Education Longitudinal Study tested 24,599 eighth-graders on several subjects, including math
and reading comprehension, in 1988 and again two and four years later.
"There was a very high correlation between the scores in eighth grade and in 12th grade," says Thomas Hoffer of the National Opinion Research Center, University of Chicago. Again, rankings hardly budged. He suspects that the way schools are organized explains some of that.
Eighth-graders who show aptitude in math or language are tracked into challenging courses. That increases the gap between them and their lower-performing peers.
"It's not that [relative student performance] can't change, but that standard practices in schools work against it," says Mr. Hoffer.
Now there is evidence that cognitive ability, or intelligence, is set before kids sit up. Developmental psychologist Marc Bornstein of the National Institute of Child Health and Human Development and colleagues followed children for four years, starting in infancy with 564 four-month olds. Babies' ability to process information can be tested in a so-called habituation test. They look at a black-on-white pattern until their attention wanes and they look away, or habituate. Later, they're shown the pattern again. How quickly they sense they've seen the image long enough, or have seen it before, is a measure of how quickly, accurately and completely they pick up, assimilate and recall information.
The scientists evaluated the children again at six months, 18 months, 24 months and 49 months. In every case, performance mirrored the relative rankings on the infant test, Dr. Bornstein and colleagues reported this year in the journal Psychological Science. Such stability, he says, "can entice" scientists to conclude that inborn, inherent, even genetic factors determine adult intelligence. But he believes crediting nature alone would be wrong.
For one thing, these tests don't measure creativity, gumption, character or other ingredients of success. For another, there are many cases of kids catching up, as when Mexican immigrant children in the U.S. start out with math skills well below their U.S.-born white peers but then catch up, says education researcher Sean Reardon of Stanford University. And as those familiar with management training and military training show, it's possible to turn even the most unpromising candidates into leaders.
That leaves the question of how current education practices (and, perhaps, parenting practices) tend to lock in early cognitive differences among children, and whether those practices can be changed in a way that unlocks every child's intellectual potential.
MUSIC, LANGUAGE, READING, MATH
- How did we get so smart?
Study sheds light on evolution of the brain
- Play's the Thing
- Intelligence is inherited Controversy
- How to Improve Thinking
- Children are hard-wired to learn by imitation even when that is clearly not the best way to learn.
Research Confirms original findings
Motor And Cognitive Skills Are Improved By Hand-Clapping Songs
- What is the evolutionary function of music? Babies begin life with synesthesia, the trippy confusion that makes people experience sounds as smells or tastes as colors. Or that the cerebellum, a part of the brain that helps govern movement, is also wired to the ears and produces some of our emotional responses to music. Watching a musician perform affects brain chemistry differently from listening to a recording. ~ Dr. Daniel Levitin
- Music - More of the Brain Used When Making Music
- Music Appreciation 'Hard Wired' in
- Evolutionary Science & Culture - why do certain melodies stick in your head and why
- Does hearing "Stairway to Heaven" remind you of your high school dance?
- Music Makes You Smarter Research
- Bottom Line Summary why Music Makes You Smarter
- Musical training during childhood may influence regional brain growth
- MUSIC AND THE BRAIN - Singing Familiar Songs is Found to Use Spatial Abilities
- Music and Literacy Research and Connections
- Music and Reading
- Study Shows Why The Arts Improve High School Reading and Math Scores
- With a Simple Tune, Students Improve In School
- Piano and Computer Training Boost Student Math Achievement
- Healthy Children - What is normal development from infant to 5 years old?
- Brain Journal Online
- Brains Rule - for Kids
Cognitive Load Theory Research
Cognitive load theory is based on a straightforward reading of information-processing concepts of memory, schema development, and automaticity of procedural knowledge: Human working memory is limited -- we can only keep in mind a few things at a time. This poses a fundamental constraint on human performance and learning capacity.
Two mechanisms to circumvent the limits or working memory are: Schema acquisition, which allows us to chunk information into meaningful units, and Automation of procedural knowledge.
The human nervous system (and the nervous systems of many other vertebrate species) has a bilateral symmetry most noticeable in the existence of the two cerebral hemispheres. The two halves of the brain, although exhibiting certain functional specializations, ordinarily work in an integrated manner to produce the conscious output of the nervous system, namely thought and action. Epilepsy is the general name given to a class of nervous system disorders involving convulsive activity of large numbers of nerve cells, and a classical surgical procedure in cases of severe epilepsy is section of the corpus callosum, the large band of nerve fibers that serves as the primary connection between the two halves of the brain. More than 30 years ago, Roger W. Sperry (1913-1994) and his coworkers began a series of studies of "split-brain" humans, patients who had had the corpus callosum severed as a therapeutic procedure, and the observations of these clinical patients have formed the basis for a number of significant ideas concerning brain function. . .
Michael S.Gazzaniga (Dartmouth College, US), a member of Sperry's original group, presents a review of the history and current status of human split-brain research, and makes the following points:
- In the classical split-brain patient, visual information no longer moves between the two sides of the brain. If an image is projected to the right visual field (i.e., to the left hemisphere, which is where information to the right field is processed) patients can describe what they see. But when the same image is displayed to the left visual field (i.e., to the right hemisphere), the patient cannot describe what they see. But if the patient is asked to point to an object similar to the object being projected, they do so with ease. The right brain sees the image and can mobilize a nonverbal response, but it cannot talk about what it sees.
- The same situation obtains for touch, smell, and sound.
- Additionally, each half of the brain can control the upper muscles of both arms, but the muscles manipulating hand and finger movements can be orchestrated only by the contralateral hemisphere. In other words, the right hemisphere can control only the left hand and the left hemisphere only the right hand.
- Ultimately, it was discovered that the two hemispheres control vastly different aspects of thought and action. Each half of the brain has its own specialization, and thus its own limitations and advantages. The left brain is dominant for language and speech, the right brain excels at visual-motor tasks.
- During the past decades, research in cognitive science, artificial intelligence, evolutionary psychology, and neuroscience has directed attention to the idea that brain and mind are built from discrete units -- or modules -- that carry out specific functions. According to this theory, the brain is not a general problem-solving device whose every part is capable of any function. Rather it is a collection of devices that assists the mind's information processing demands.
"After many years of fascinating research on the split brain, it appears that the inventive and
interpreting left hemisphere has a conscious experience very different from that of the truthful, literal
right brain. Although both hemispheres can be viewed as conscious, the left brain's consciousness far
surpasses that of the right. Which raises another set of questions that should keep us busy for the next 30
years or so." (Scientific American July 1998) (Science-Week 10 Jul 98)
ON MODULAR COGNITIVE SYSTEMS IN THE HUMAN BRAIN
One of the central challenges of cognitive neuroscience is to unmask the apparent unitary nature of perceptual, memorial, and cognitive systems. Neuropsychological analyses, functional brain-imaging methods, and analyses of normal reaction times have revealed that apparently unitary processes consist of multiple components. Frequently, these multiple components are distributed across the cerebral hemispheres, but appear unified because of the integration possible via the corpus callosum.
... Baynes et al (4 authors at 3 installations, US) report a case of elective surgery for a severe epileptic disorder, the surgery involving a resection of the corpus callosum in a left- handed woman with left-hemisphere dominance for spoken language. The patient demonstrated a dissociation between spoken andwritten language. Words flashed to the dominant left hemisphere were easily spoken out loud, but could not be written. When words were flashed to the patient's right hemisphere, she could not speak them out loud but she could write them with her left hand. The authors suggest this marked dissociation supports the view that spoken and written language output can be controlled by independent hemispheres, even if before hemispheric disconnection spoken and written language appear as inseparable cognitive entities. QY: Kathleen Baynes (firstname.lastname@example.org) (Science 8 May 98 280:902) (Science-Week 29 May 98)
BRAIN PLASTICITY IN CHILDREN AFTER HEMISPHERECTOMY
Epilepsy is a term unhappily applied to several dozen different seizure disorders, their commonality being central nervous system seizures rather than identical pathological processes causing the seizures. From a neurophysiological standpoint, a seizure is the end result of a massive discharge of nerve cells, often the motor neuron pathways that activate muscle cells. Seizures can be produced by various central nervous system infections, metabolic disturbances, toxic agents, cerebral oxygen deficiency, expanding brain lesions, cerebral trauma, cerebral hemorrhage, and so on. In general, any physiological event or series of events that produces a wide disruption of central nervous system activity has the potential for production of seizures of one sort or another. Most patients who for reasons known (symptomatic epilepsies) or unknown (idiopathic epilepsies) are chronically subjected to seizures can be helped with various pharmacological agents such as phenytoin or cloneazepam, but 10% to 20% of patients have seizures that cannot be managed by drugs. If the seizures are due to a specific damaged locus in the brain (the "epileptic focus"), the recourse for these patients, if the locus can be determined, is surgery. What is done is to completely remove the epileptic focus, sometimes an area no larger than a small coin, and if the surgery is successful the cure is immediate and permanent. There are cases, however, in which the affected part of the brain is quite large, the seizures completely unmanageable, and the only recourse is radical surgery. Since severe chronic epilepsy due to brain lesions is usually first diagnosed in young children, it is such children who are the usual patients in radical brain surgery for epilepsy. The most radical and fairly common procedure is hemispherectomy, removal of an entire half of the brain, and the most remarkable aspect of this is that when the surgical procedure is successful, not only are the seizures eliminated, but the child can function as well or almost as well as any other child. It is an example of a phenomenon well-known to neuro- biologists called "brain plasticity", the ability of the brain to recover the function of a damaged or removed region by assignment of the function to an undamaged location. The language area of the brain, for example, is often considered to be fixed on the left side of the brain by genetics, but in truth it is not so fixed, and if the left side of the brain is removed at an early age, the right side of the brain will quickly develop a language center and there will be little functional impairment. In a recent publication, Eileen P. G. Vining (Johns Hopkins Univ- ersity, Baltimore MD US) reports the progress of 54 children who underwent hemispherectomy for recurrent severe epileptic seizures. The majority of the patients were seizure-free following surgery, no longer needed drugs, and many of the patients are now in school. One of the most significant facts about the human brain is that its histological development continues at least until adolescence, and the dynamism of this histological development is what is responsible for its remarkable plasticity.
Female and Male Origin Of The Brain
Due to genomic imprinting [something that only happens in mammals], the genes for developing our emotional limbic brain come from our fathers and those for a more rational neocortical brain from our mothers. See the easy to read discussion of this research from the New Scientist 'Where did you get your brains?'
No body has explained why female genes should encode neocortical and male ones limbic brain development. It come from the fact that female and male genes are selected in different circumstances.If you are low class, your best chance of reproductive success are daughters that marry up. So you selectively kill more males than females and in other ways favour daughters. On the other hand, if you are high class, your best chance of reproductive success are sons that sow their seed in the lower classes. In effect, selection is gender compartmentalized with males of the population being selected in the higher class, and females in the lower one.
The circumstances of selection are different in higher and lower classes. Thus genes shaping the males of the population reflect the selection to males happening in the higher class where there are good and reliable resources, and genes of females of the population, the selection of females in the lower one where resources are less reliable.
Where there are good resources, gene selection will depend more upon winning reproductive opportunities than mere physical survival since there will be many more competitors for reproductive opportunities [with lots of resources, survival of potential competitors is greater]; conversely, where resources are poor, gene selection will depend upon smartness in getting resources and surviving to be an adult, rather than getting reproductive opportunities [genes are being winnowed out before this stage].
Now winning reproductive opportunities is going to need both limbic and neocortical abilities, likewise survival against the adversities of nature. But there will be a bias for emotional factors in winning reproductive opportunities [think of the social incompetence of autistic individuals smart as Dr. Spock and Data] while survival against nature does not depend upon emotions but shear cunning and resourcefulness. If so, our limbic brain might be selected by higher status males with their winning emotional responses, and our neocortical brain by lower status females with the wits to avoid danger and starvation.
Of course, other stories are possible but it is interesting to ask why different parts of brains have different male and female origins.
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