general on brain

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GENERAL ON BRAIN...

http://www.brainology.us/webnav/whatismindset.aspx

The Research behind Brainology: The Growth Mindset

Mindset is a simple idea discovered by Stanford professor, Carol S. Dweck, Ph.D., in decades of

research on motivation, achievement, and success. Mindsets are beliefs individuals hold about

their most basic qualities and abilities. In a Growth Mindset, people believe they can developtheir brain, abilities, and talent. This view creates a love for learning, a drive for growth and a

resilience that is essential for great accomplishments. On the contrary, people with a FixedMindset believe their basic qualities, such as intelligence and abilities are fixed, and can't be

developed. They also believe that talent alone creates success, and see effort as a sign ofweakness rather than as a positive element of life needed to reach one's full potential.

The following diagram shows how people with different views of intelligence behave in differentsituations:


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Changing students Mindset with Brainology

The great news is that students and adults can shift their mindset from a Fixed Mindset to

a Growth Mindset! Brainology

is designed to do that. Brainology

helps students to change

their beliefs, develop a Growth Mindset, and consequently, reach a higher level of academicachievement. These were the main research goals of our co-founders Carol S. Dweck,

Ph.D. and Lisa Sorich Blackwell, Ph.D. when they designed the program. They discovered thatdeveloping a Growth Mindset is critical to adopting learning-oriented behavior. Later, they

developed the Brainology

Program to help students cultivate the Growth Mindset by teachingthem the powerful combination of neuroscience and study skills.

Brainology

explains:

y How the brain works and how its function can be increased.y How the learning process physically changes the brain and why adopting learning goals is critical

to success.

y Why effort and diligence are positive even when they involve hard work or initial failures.y How to apply brain-friendly, effort-based strategies that focus on working harder, smarter, and

with a focus on growth.

y How to cope with challenges and difficulties and how to overcome failures.Brainology

is a research based program, based on decades of studies by leading researchers in the area

of motivation. Brainology has been tested in many schools and has shown that teaching students that

the brain grows and strengthens every time they learn something new increases students' motivation,

engagement, and achievements. When students realize that they control their learning, they are

motivated to apply effort and take an active role in learning. Teachers perceive this new awareness as

changes in students' behavior (becoming engaged in class, reflecting, asking questions, doinghomework), as well as in the higher student achievement that results from more motivated students

with higher expectations of themselves.

The Shttp://www.brainology.us/webnav/growth-mindset-

research.aspxcience: The Growth MindsetOver the past two decades, the main goal of our co-founders Carol S. Dweck, Ph.D. and Lisa Sorich

Blackwell, Ph.D. has been to research what helps students to achieve highly, and to apply the lessons

learned to improving their motivation and achievement. They discovered that developing a growth

mindset (the core belief that abilities are malleable and not fixed) is critical to adopting learning-

oriented behavior. Dr. Blackwell and Dr. Dweck then developed the Brainology

Program in order to

help students cultivate a growth mindset.


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Below is information on the growth mindset research background. You can also view a visual,summary presentation of the growth mindset research that led to the Brainology

Program.

Achievement Motivation

In Drs. Dweck and Blackwells research, we have found that the beliefs and attitudes held by

students when they begin junior high school have a strong influence on their achievement overthese critical years.

In particular, the research found that students who believed that their intelligence was somethingthat they could develop and increasewhat we term a growth mindsetalso held many other

positive attitudes. First, believing that their ability could be increased, they valued learning as agoal, even when it involved hard work or initial errors. They also believed in the efficacy of

effortthat is, they viewed effort in a positive way and felt that they had the ability, throughtheir own efforts, to learn and master new material up to standard. When they had difficulty in a

subject, they made more constructive, mastery-oriented explanationsrather than just saying,Im not smart enough, or I just cant do math, they explained their difficulty as due to lack of

effort or inadequate strategy. And they responded with more positive, effort-based strategies towork harder and spend more time on the subject instead of giving up.

Even more striking, students with a growth mindset had an upward trajectory in mathematicsgrades over seventh and eighth grade, while those who viewed their intelligence as a fixed

quality did not. This was true even though students had equal levels of prior achievement:students who believed that their intelligence was malleable did better than did equally able

students who viewed their intelligence as an unchangeable, fixed entity. This was true forstudents at all levels of ability.

Our research, as well as that of others, has shown that students who hold a growth mindset usemore sophisticated strategies in their coursework. For example, they use more complex

cognitive and meta-cognitive strategiesthose that involve active and deeper-level processing ofmaterial, and self-monitoring of the learning process.

Research on Learning and the Brain

In the same period of time, research has shown that the brain is in fact much more malleable than

previously thought. It was once believed that the brain did not grow new cells, and that there were

severe limitations on the malleability, or neuroplasticity, of the brain after early childhood. But in the

past few decades, research has shown that learning causes substantial changes in the brains of both

animals and human beings throughout life.

Thinking occurs in the brain through the chemical communication of nerve cells connected in a complex

network. With learning, the cells of the brain develop new connections between them, and existing

connections become stronger. Studies in neurophysiology, neuroanatomy, and brain imaging have

shown that when people practice and learn new skills, the areas of the brain responsible for those skills

actually become larger and denser with neural tissue, and that new areas of the brain become active

when performing related tasks. Furthermore, it has been found that the brain continues to grow new

nerve cells, or neurons, daily, and that this process speeds up when a lot of active learning is occurring.

Thus, the brain has the capacity to develop throughout life. However, this development depends on the

stimulation of challenge and learning. This fact makes it all the more critical that students be given

challenging material and motivated to apply effort and take an active role in learning.


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Instructor-Led Intervention Approach: Teaching a Growth MindsetWould it be possible to improve

students motivation and achievement by teaching them a growth mindset? In a pilot study we did just

that by teaching middle school students about what has been learned about the flexibility of the brain to

develop and grow new networks with challenge and learning (this was done by an instructor in-person,

rather than through software). We then examined changes in the students motivation and

mathematics achievement over the year of the intervention, comparing them with a similar group of

students in the same school who did not receive this intervention.


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Provessssss.

Instructor-Led Pilot Study Results

Gains in motivation:

We asked teachers to assess changes in their students classroom motivation over the period of the

intervention. Note that in the pilot study we taught the growth mindset intervention to students

outside of their class periods, and teachers did not participate in the intervention. Thus, teachers were

unfamiliar with the content of the intervention, and they did not know which of their students had

received instruction in the malleable brain. Yet teachers cited significantly more of the students who

had received the growth mindset training as showing positive change in their effort and interest in.

Teacher Comments Following Instructor-Led Intervention

M. was performing far below grade level. During the past few weeks, she has voluntarily asked for

extra help from me during her lunch period in order to improve her test-taking performance. Her

grades drastically improved from failing to an 84 on the most-recent exam.Lately I have noticed that

students have a greater appreciation for improvement in academic performance . R. was performingbelow standards, but now he has learned to appreciate the improvement from his grades of 52, 46, and

49 to his grades of 67 and 71. He valued his growth in learning Mathematics.Your workshop has

already had an effect. L., who never puts in any extra effort and often doesnt turn in homework on

time, actually stayed up late working for hours to finish an assignment early so I could review it and give

him a chance to revise it. He earned a B+ on the assignment (he had been getting Cs and

lower).Several students have voluntarily participated in peer tutoring sessions during their lunch

periods or after school. These students were passing when they requested the extra help and motivated

by the prospect of sheer improvement.

Gains in MathAchievement:

The mathematics grades of all students in the study had been declining prior to theintervention. However, after the intervention, the grades of those students who learned about the

growth mindset (experimental group) took an upward turn, while those of their fellow students who did

not receive this curriculum continued to decline.

References

y Blackwell, L., Trzesniewski, K., & Dweck, C. (2007). Implicit Theories ofIntelligence PredictAchievement Across an Adolescent Transition: A Longitudinal Study and an Intervention. Child

Development, Vol. 78, No. 1, pp. 246-263.

y Mueller, C. M., & Dweck, C. S. (1998). Intelligence praise can undermine motivation andperformance. Journal of Personality and Social Psychology, 75, 33-52.

y Dweck, C. (2006). Mindset: The New Psychology of Success. Random House: New York.For more information, please view Carol Dweck's research studies.


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Acknowledgements

Dr. Dweck and Dr. Blackwells research has been funded by grants from the William T. Grant Foundation

and the Spencer Foundation.

http://www.livescience.com/strangenews/070802_gm_brain.html

Strange News

Greatest Mysteries: How Does the Brain Work?

By Jeanna Bryner, LiveScience Staff Writer

posted: 02 August 2007 09:04 am ET

Buzz up!

Comments (2) | Recommend (9)

Editor's Note:We asked several scientists from various fields what they thought were the

greatest mysteries today, and then we added a few that were on our minds, too. This article isone of 15 in LiveScience's "Greatest Mysteries" series running each weekday.

Our brains can fathom the beginning of time and the end of the universe, but is any brain capable

of understanding itself?

With billions of neurons, each with thousands of connections, one's noggin is a complex, and yes

congested, mental freeway. Neurologists and cognitive scientists nowadays are probing how themind gives rise to thoughts, actions, emotions and ultimately consciousness.

The complex machine is difficult for even the brainiest of scientists to wrap their heads around.But the payoff for such an achievement could be huge.

If we understand the brain, we will understand both its capacities and its limits for thought,

emotions, reasoning, love and every other aspect of human life, said Norman Weinberger, a

neuroscientist at the University of California, Irvine.

Brain teasers

What makes the brain such a tough nut to crack?

According to Scott Huettel of the Center for Cognitive Neuroscience at Duke University, thestandard answer to this question goes something like: The human brain is the most complex


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object in the known universe ... complexity makes simple models impractical and accuratemodels impossible to comprehend.

While that stock answer is correct, Huettel said, its incomplete. The real snag in brain science is

one of navel gazing. Huettel and other neuroscientists cant step outside of their own brains (and

experiences) when studying the brain itself.

A more pernicious factor is that we all think we understand the brainat least our own

through our experiences. But our own subjective experience is a very poor guide to how thebrain works, Huettel toldLiveScience.

Whether the human brain can understand itself is one of the oldest philosophical questions,said Anders Garm of the University of Copenhagen, Denmark, a biologist who studies jellyfish

as models for human neural processing of visual information.

Mental mechanics

Scientists have made some progress in taking an objective, direct look at the human brain.

In recent years, brain-imaging techniques, such as functional magnetic resonance imaging

(fMRI) have allowed scientists to observe the brain in action and determine how groups ofneurons function.

They have pinpointed hubs in the brain that are responsible for certain tasks, such as fleeing a

dangerous situation, processing visual information, making those sweet dreams and storing long-term memories. But understanding the mechanics of how neuronal networks collaborate to allow

such tasks has remained more elusive.

We do not yet have a good way to study how groups of neurons form functional networks whenwe learn, remember, or do anything else, including seeing, hearing moving, loving, Weinberger

said.

Plus these clusters of brain cells somehow give rise to more complex behaviors and emotions,

such as altruism, sadness, empathy and anger.

Huettel and his colleagues used fMRIs to discover a region in the brain linked with altruisticbehavior.

"Although understanding the function of this brain region may not necessarily identify whatdrives people like Mother Teresa, Huettel said, it may give clues to the origins of importantsocial behaviors like altruism.

Who am I?

The prized puzzle in brain research is arguably the idea of consciousness. When you look at apainting, for instance, you are aware of it and your mind processes its colors and shapes. At the


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same time, the visual impression could stir up emotions and thoughts. This subjective awarenessand perception is consciousness.

Many scientists consider consciousness the delineation between humans and other animals.

So rather than cognitive processes directly leading to behaviors (unbeknownst to us), we areaware of the thinking. We even know that we know!

If this mind bender is ever solved, an equally perplexing question would arise, according to

neuroscientists: Why? Why does awareness exist at all?

Ultimately, Weinberger said, understanding the brain will enable us to understand what it trulyis to be human.

Comments (2)

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posted 13 June 2010, 8:03 am ET

redinsmit wrote:Did you ever think that we are all machines? Complex no doubt, but machines

none the less. Seeded here by some other world as a science experiment or

because there world was dying or some other reason. I%u2019m not saying there

is no God; and I don%u2019t need thousands of religions beating up on me. We

are created, no doubt and not equal. We think of machines as metallic,

robotic, and programmable. An old man with an IQ of less than 90 once said

%u201CI can%u2019t think of a thing that I don%u2019t already know%u201D a

very profound statement. We have come a long way in the last 200 years. We

are young as a society, and yet we are frustrated that we don%u2019t know

everything. I%u2019m fairly sure we were created to learn slowly so to keep

us from killing ourselves before we complete or mission whatever that is.

There are and were a few, Nikola Tesla, Albert Einstein, Arthur Clarke,

Stephen Hawking, and others that I do not know or think of at this time that

broke barriers and thought of things that were science fiction and now are

science fact.

All the things we don%u2019t understand are here, we will discover them when

the time comes. Yes we are capable of learning them now we just haven%u2019tstumbled across them yet. Quantum drives, transporters, antimatter reactors

are in the near future. Just wait 200 more years. Oh yeah, you%u2019ll be

dead, maybe not. We are very close to understanding what makes us begin to

get old and be able to turn it off. The problem will be who gets to live

forever, will we still have children, where will they live. Probably the same

problems the ones that sent us here have or had. Maybe this is the reason

for us being here.

We keep making technological advances to make our life easier, and then we

must go to the gym, exercise, diet to keep from being sick. I have a very


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easy job that pays well but demands me to sit on my butt a lot. I find that

when I do physical labor I am much healthier less bored and generally

happier, but it doesn%u2019t pay enough to keep my family in the standard of

living they are accustomed. So I keep sitting on my butt, paying a trainer to

make me do the things I must do to keep me from being obese, diabetic, and

dying of heart failure.

Are we just machines in a science experiment? Probably so. Will we ever know

for sure? Someday.

All you people that know %u201Cit%u2019s out there%u201D keep trying to

focus, it will come to you. Even I have moments of clarity, when I%u2019m

not rambling

Tim

Reply | Recommend (4) | Report Abuse

posted 19 July 2010, 4:22 pm ET

dan2see wrote:I think the animals (or at least the larger mammals) are actually very

intelligent, conscious, and self-aware. I get this idea from watching our pet

dogs and cats, and I think horses, too.

Not only that, but I think that we got our intelligence from the animals, via

evolution. Most of the mental facilities and tools were developed in the

wild, because they served the animal to live, to keep itself healthy and

useful in the outdoor environment, and to get along with its society.

So features like analytic vision, hand-eye coordination, pace and rhythm

while walking and running, and exploring nature to find good things to eat,

and bad things to avoid. Rabbits and dogs could not possibly survive without

these facilities. You can add abstract features like memory, judgement,

happiness, and goal-setting, and dreams.

Of course all animals communicate, but only humans have language. I also

guess that our long-term memory is superior, too.

- Daniel in Calgary

Reply | Recommend (0) | Report Abuse

Human brainFrom Wikipedia, the free encyclopedia

Jump to: navigation, search

This article is about features specific to the human brain. For basic information about brains, see brain.

Human brain


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Human brain and skull

Cerebral lobes: the frontal lobe (pink), parietal lobe (green) and occipital lobe (blue)

Latin Cerebrum

Gray's subject #184 736

SystemCentral nervous system

ArteryAnterior communicating artery, middle cerebral

artery

VeinCerebral veins, external veins, basal vein, terminal

vein, choroid vein, cerebellar veins

The human brain is the center of the human nervous system. Enclosed in the cranium, it has the

same general structure as the brains of othermammals, but is over three times as large as thebrain of a typical mammal with an equivalent body size.

[1]Most of the expansion comes from the

cerebral cortex, a convoluted layer of neural tissue that covers the surface of the forebrain.Especially expanded are the frontal lobes, which are associated with executive functions such as

self-control, planning, reasoning, and abstract thought. The portion of the brain devoted to vision

is also greatly enlarged in human beings.

Brain evolution, from the earliest shrewlike mammals throughprimates to hominids, is markedby a steady increase in encephalization, or the ratio of brain to body size. The human brain has

been estimated to contain 50100 billion (1011) neurons, of which about 10 billion (1010) arecortical pyramidal cells. These cells pass signals to each other via as many as 1000 trillion (10

15,

1 quadrillion) synaptic connections.[2]

However, recent research has shown that the modernhuman brain has actually been shrinking over the last 28,000 years.

[3]One explanation for this is


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that the social safety net created by living in societies has allowed humans of lesser intelligenceto survive and procreate.

[citation needed]

The brain monitors and regulates the body's actions and reactions. It continuously receives

sensory information, and rapidly analyzes this data and then responds, controlling bodily actions

and functions. Thebrainstem controls breathing, heart rate, and otherautonomic processes thatare independent of conscious brain functions. The neocortex is the center of higher-orderthinking, learning, and memory. The cerebellum is responsible for the body's balance, posture,

and the coordination of movement.

In spite of the fact that it is protected by the thick bones of the skull, suspended in cerebrospinalfluid, and isolated from the bloodstream by theblood-brain barrier, the delicate nature of the

human brain makes it susceptible to many types of damage and disease. The most commonforms of physical damage are closed head injuries such as a blow to the head, a stroke, or

poisoning by a wide variety of chemicals that can act as neurotoxins. Infection of the brain is rarebecause of the barriers that protect it, but is very serious when it occurs. The human brain is also

susceptible to degenerative disorders, such as Parkinson's disease, multiple sclerosis, andAlzheimer's disease. A number of psychiatric conditions, such as schizophrenia and depression,

are widely thought to be caused at least partially by brain dysfunctions, although the nature ofsuch brain anomalies is not well understood.


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Contents

[hide]

y 1 Structureo 1.1 General featureso 1.2 Cortical divisions

1.2.1 Four lobes 1.2.2 Functional divisions

o 1.3 Topographyo 1.4 Lateralization

y 2 Developmenty 3 Sources of information

o 3.1 EEGo 3.2 MEGo 3.3 Structural and functional imagingo 3.4 Effects of brain damage

y 4 Languagey 5 Pathologyy 6 Metabolismy 7 See alsoy 8 Notesy 9 Referencesy 10 External links

[edit] Structure

Bisection of the head of an adult man, showing the cerebral cortex and underlying white matter[4]

The adult human brain weighs on average about 3 lb (1.5 kg)[5] with a size (volume) of around

1130 cubic centimetres (cm3) in women and 1260 cm

3in men, although there is substantial

individual variation.[6]

Men with the same body height and body surface area as women have on


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average 100g heavier brains,[7]

although these differences do not correlate in any simple waywith gray matter neuron counts or with overall measures of cognitive performance.

[8]

Neanderthals, an extinct subspecies of modern humans, had larger brains at adulthood thanpresent-day humans.[9] The brain is very soft, having a consistency similar to soft gelatin or firm

tofu.[10]

Despite being referred to as "grey matter", the live cortex is pinkish-beige in color and

slightly off-white in the interior. At the age of 20, a man has around 176,000 km and a womanabout 149,000 km of myelinated axons in their brains.[11]

[edit] General features

Drawing of the human brain, showing several important structures

The cerebral hemispheres form the largest part of the human brain and are situated above most

other brain structures. They are covered with a cortical layerwith a convoluted topography.[12]

Underneath the cerebrum lies thebrainstem, resembling a stalk on which the cerebrum is

attached. At the rear of the brain, beneath the cerebrum and behind the brainstem, is thecerebellum, a structure with a horizontally furrowed surface that makes it look different from any

other brain area. The same structures are present in other mammals, although the cerebellum isnot so large relative to the rest of the brain. As a rule, the smaller the cerebrum, the less

convoluted the cortex. The cortex of a rat or mouse is almost completely smooth. The cortex of adolphin or whale, on the other hand, is more convoluted than the cortex of a human.

The dominant feature of the human brain is corticalization. The cerebral cortex in humans is so

large that it overshadows every other part of the brain. A few subcortical structures showalterations reflecting this trend. The cerebellum, for example, has a medial zone connected

mainly to subcortical motor areas, and a lateral zone connected primarily to the cortex. In

humans the lateral zone takes up a much larger fraction of the cerebellum than in most othermammalian species. Corticalization is reflected in function as well as structure. In a rat, surgicalremoval of the entire cerebral cortex leaves an animal that is still capable of walking around and

interacting with the environment.[13]

In a human, comparable cerebral cortex damage produces apermanent state ofcoma. The amount of association cortex, relative to the other two categories,

increases dramatically as one goes from simpler mammals, such as the rat and the cat, to morecomplex ones, such as the chimpanzee and the human.

[14]


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Major gyri and sulci on the lateral surface of the cortex

The cerebral cortex is essentially a sheet of neural tissue, folded in a way that allows a large

surface area to fit within the confines of the skull. Each cerebral hemisphere, in fact, has a total

surface area of about 1.3 square feet.[15] Anatomists call each cortical fold a sulcus, and thesmooth area between folds a gyrus. Most human brains show a similar pattern of folding, but

there are enough variations in the shape and placement of folds to make every brain unique.Nevertheless, the pattern is consistent enough for each major fold to have a name, for example,

the "superior frontal gyrus", "postcentral sulcus", or "trans-occipital sulcus". Deep folding

features in brain such as the inter-hemispheric and lateral fissure, and the insular cortex arepresent in almost all normal subjects.

[edit] Cortical divisions

The four lobes of the cerebral cortex

The bones of the human skull


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edit] Four lobes

Outwardly, the cerebral cortex is nearly symmetrical, with left and right hemispheres.Anatomists conventionally divide each hemisphere into four "lobes", the frontal lobe,parietallobe, occipital lobe, and temporal lobe. This categorization does not actually arise from the

structure of the cortex itself: the lobes are named after the bones of the skull that overlie them.There is one exception: the border between the frontal and parietal lobes is shifted backward to

the central sulcus, a deep fold that marks the line where the primary somatosensory cortex andprimary motor cortex come together.

[edit] Functional divisions

This section does not cite any references or sources.

Please help improve this article by adding citations to reliable sources. Unsourced material may be

challenged and removed. (September 2009)

Researchers who study the functions of the cortex divide it into three functional categories of

regions, or areas. One consists of the primary sensory areas, which receive signals from thesensory nerves and tracts by way of relay nuclei in the thalamus. Primary sensory areas includethe visual area of the occipital lobe, the auditory area in parts of the temporal lobe and insular

cortex, and the somatosensory area in theparietal lobe. A second category is the primary motorarea, which sends axons down to motor neurons in the brainstem and spinal cord. This area

occupies the rear portion of the frontal lobe, directly in front of the somatosensory area. The thirdcategory consists of the remaining parts of the cortex, which are called the association areas.

These areas receive input from the sensory areas and lower parts of the brain and are involved inthe complex process that we call perception, thought, and decision making.

Brodmann's classification of areas of the cortex

Different parts of the cerebral cortex are involved in different cognitive and behavioral functions.The differences show up in a number of ways: the effects of localized brain damage, regional

activity patterns exposed when the brain is examined using functional imaging techniques,connectivity with subcortical areas, and regional differences in the cellular architecture of the

cortex. Anatomists describe most of the cortexthe part they call isocortexas having sixlayers, but not all layers are apparent in all areas, and even when a layer is present, its thickness

and cellular organization may vary. Several anatomists have constructed maps of cortical areason the basis of variations in the appearance of the layers as seen with a microscope. One of the


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most widely used schemes came from Brodmann, who split the cortex into 51 different areas andassigned each a number (anatomists have since subdivided many of the Brodmann areas). For

example, Brodmann area 1 is the primary somatosensory cortex, Brodmann area 17 is theprimary visual cortex, and Brodmann area 25 is the anterior cingulate cortex.

[edit] Topography

Topography of the primary motor cortex, showing which body part is controlled by each zone

Many of the brain areas Brodmann defined have their own complex internal structures. In a

number of cases, brain areas are organized into "topographic maps", where adjoining bits of thecortex correspond to adjoining parts of the body, or of some more abstract entity. A simple

example of this type of correspondence is the primary motor cortex, a strip of tissue runningalong the anterior edge of the central sulcus, shown in the image to the right. Motor areas

innervating each part of the body arise from a distinct zone, with neighboring body partsrepresented by neighboring zones. Electrical stimulation of the cortex at any point causes a

muscle-contraction in the represented body part. This "somatotopic" representation is not evenlydistributed, however. The head, for example, is represented by a region about three times as large

as the zone for the entire back and trunk. The size of a zone correlates to the precision of motorcontrol and sensory discrimination possible

[citation needed]. The areas for the lips, fingers, and

tongue are particularly large, considering the proportional size of their represented body parts.

In visual areas, the maps are retinotopicthat is, they reflect the topography of the retina, the

layer of light-activated neurons lining the back of the eye. In this case too the representation isuneven: the foveathe area at the center of the visual fieldis greatly overrepresented

compared to the periphery. The visual circuitry in the human cerebral cortex contains severaldozen distinct retinotopic maps, each devoted to analyzing the visual input stream in a particular

way[citation needed]. The primary visual cortex (Brodmann area 17), which is the main recipient ofdirect input from the visual part of the thalamus, contains many neurons that are most easily

activated by edges with a particular orientation moving across a particular point in the visualfield. Visual areas farther downstream extract features such as color, motion, and shape.

In auditory areas, the primary map is tonotopic. Sounds are parsed according to frequency (i.e.,

high pitch vs. low pitch) by subcortical auditory areas, and this parsing is reflected by theprimary auditory zone of the cortex. As with the visual system, there are a number of tonotopic

cortical maps, each devoted to analyzing sound in a particular way.

Within a topographic map there can sometimes be finer levels of spatial structure. In the primaryvisual cortex, for example, where the main organization is retinotopic and the main responses are


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to moving edges, cells that respond to different edge-orientations are spatially segregated fromone another

[citation needed].

[edit] Lateralization

Main article: Lateralization of brain function

Routing of neural signals from the two eyes to the brain

Each hemisphere of the brain interacts primarily with one half of the body, but for reasons that

are unclear, the connections are crossed: the left side of the brain interacts with the right side of

the body, and vice versa.[citation needed]

Motor connections from the brain to the spinal cord, and

sensory connections from the spinal cord to the brain, both cross the midline at brainstem levels.Visual input follows a more complex rule: the optic nerves from the two eyes come together at apoint called the optic chiasm, and half of the fibers from each nerve split off to join the other.

The result is that connections from the left half of the retina, in both eyes, go to the left side ofthe brain, whereas connections from the right half of the retina go to the right side of the brain.

Because each half of the retina receives light coming from the opposite half of the visual field,the functional consequence is that visual input from the left side of the world goes to the rightside of the brain, and vice versa. Thus, the right side of the brain receives somatosensory input

from the left side of the body, and visual input from the left side of the visual fieldanarrangement that presumably is helpful for visuomotor coordination.


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The corpus callosum, a nerve bundle connecting the two cerebral hemispheres, with the lateral

ventricles directly below

The two cerebral hemispheres are connected by a very large nerve bundle called the corpus

callosum, which crosses the midline above the level of the thalamus. There are also two muchsmaller connections, the anterior commisure and hippocampal commisure, as well as many

subcortical connections that cross the midline. The corpus callosum is the main avenue ofcommunication between the two hemispheres, though. It connects each point on the cortex to the

mirror-image point in the opposite hemisphere, and also connects to functionally related points indifferent cortical areas.

In most respects, the left and right sides of the brain are symmetrical in terms of function. Forexample, the counterpart of the left-hemisphere motor area controlling the right hand is the right-

hemisphere area controlling the left hand. There are, however, several very important exceptions,involving language and spatial cognition. In most people, the left hemisphere is "dominant" for

language: a stroke that damages a key language area in the left hemisphere can leave the victimunable to speak or understand, whereas equivalent damage to the right hemisphere would cause

only minor impairment to language skills.

A substantial part of our current understanding of the interactions between the two hemisphereshas come from the study of "split-brain patients"people who underwent surgical transection of

the corpus callosum in an attempt to reduce the severity of epileptic seizures. These patients donot show unusual behavior that is immediately obvious, but in some cases can behave almost like

two different people in the same body, with the right hand taking an action and then the left handundoing it. Most such patients, when briefly shown a picture on the right side of the point of

visual fixation, are able to describe it verbally, but when the picture is shown on the left, areunable to describe it, but may be able to give an indication with the left hand of the nature of the

object shown.

It should be noted that the differences between left and right hemispheres are greatly overblownin much of the popular literature on this topic. The existence of differences has been solidly

established, but many popular books go far beyond the evidence in attributing features ofpersonality or intelligence to the left or right hemisphere dominance.

[citation needed]

[edit] Development

Main article: Neural development in humans

During the first 3 weeks of gestation, the human embryo's ectoderm forms a thickened stripcalled the neural plate. The neural plate then folds and closes to form the neural tube. This tubeflexes as it grows, forming the crescent-shaped cerebral hemispheres at the head, and the

cerebellum and pons towards the tail.


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Brain of human embryo at 4.5 weeks,

showing interior of forebrain

Brain interior at 5 weeks


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Brain viewed at midline at 3 months

[edit] Sources of information

Neuroscientists, along with researchers from allied disciplines, study how the human brain

works. Such research has expanded considerably in recent decades. The "Decade of the Brain",an initiative of the United States Government in the 1990s, is considered to have marked much

of this increase in research.[16]

Information about the structure and function of the human brain comes from a variety ofexperimental methods. Most information about the cellular components of the brain and how

they work comes from studies of animal subjects, using techniques described in thebrain article.Some techniques, however, are used mainly in humans, and therefore are described here.

Computed tomography of human brain, from base of the skull to top, taken with intravenous contrast

medium

[edit] EEG

By placing electrodes on the scalp it is possible to record the summed electrical activity of the

cortex, in a technique known as electroencephalography (EEG).[17]

EEG measures mass changes

in population synaptic activity from the cerebral cortex, but can only detect changes over largeareas of the brain, with very little sensitivity for sub-cortical activity. EEG recordings can detect

events lasting only a few thousandths of a second. EEG recordings have good temporalresolution, but poor spatial resolution.


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[edit] MEG

Apart from measuring the electric field around the skull it is possible to measure the magnetic

field directly in a technique known as magnetoencephalography (MEG).[18]

This technique hasthe same temporal resolution as EEG but much better spatial resolution, although not as good as

Magnetic Resonance Imaging (MRI). The greatest disadvantage of MEG is that, because themagnetic fields generated by neural activity are very weak, the method is only capable of picking

up signals from near the surface of the cortex, and even then, only neurons located in the depthsof cortical folds (sulci) have dendrites oriented in a way that gives rise to detectable magnetic

fields outside the skull.

[edit] Structural and functional imaging

Main article: Neuroimaging

A scan of the brain using fMRI

There are several methods for detecting brain activity changes by three-dimensional imaging of

local changes in blood flow. The older methods are SPECT and PET, which depend on injectionof radioactive tracers into the bloodstream. The newest method, functional magnetic resonance

imaging (fMRI), has considerably better spatial resolution and involves no radioactivity.[19]Using the most powerful magnets currently available, fMRI can localize brain activity changes toregions as small as one cubic millimeter. The downside is that the temporal resolution is poor:

when brain activity increases, the blood flow response is delayed by 15 seconds and lasts for atleast 10 seconds. Thus, fMRI is a very useful tool for learning which brain regions are involved

in a given behavior, but gives little information about the temporal dynamics of their responses.A major advantage for fMRI is that, because it is non-invasive, it can readily be used on human

subjects.

[edit] Effects of brain damage

Main article: Neuropsychology

A key source of information about the function of brain regions is the effects of damage tothem.[20] In humans, strokes have long provided a "natural laboratory" for studying the effects of

brain damage. Most strokes result from a blood clot lodging in the brain and blocking the localblood supply, causing damage or destruction of nearby brain tissue: the range of possible

blockages is very wide, leading to a great diversity of stroke symptoms. Analysis of strokes islimited by the fact that damage often crosses into multiple regions of the brain, not along clear-

cut borders, making it difficult to draw firm conclusions.


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[edit] Language

Location of two brain areas that play a critical role in language, Broca's area and Wernicke's area

In human beings, it is the left hemisphere that usually contains the specialized language areas.

While this holds true for 97% of right-handed people, about 19% of left-handed people havetheir language areas in the right hemisphere and as many as 68% of them have some language

abilities in both the left and the right hemisphere.[citation needed] The two hemispheres are thought tocontribute to the processing and understanding of language: the left hemisphere processes the

linguistic meaning ofprosody (or, the rhythm, stress, and intonation ofconnected speech), whilethe right hemisphere processes the emotions conveyed by prosody.[21] Studies of children have

shown that if a child has damage to the left hemisphere, the child may develop language in theright hemisphere instead. The younger the child, the better the recovery. So, although the

"natural" tendency is for language to develop on the left, human brains are capable of adapting todifficult circumstances, if the damage occurs early enough.

The first language area within the left hemisphere to be discovered is Broca's area, named after

Paul Broca, who discovered the area while studying patients with aphasia, a language disorder.

Broca's area doesn't just handle getting language out in a motor sense, though. It seems to bemore generally involved in the ability to process grammar itself, at least the more complexaspects of grammar. For example, it handles distinguishing a sentence in passive form from a

simpler subject-verb-object sentence the difference between "The boy was hit by the girl" and"The girl hit the boy."

The second language area to be discovered is called Wernicke's area, afterCarl Wernicke, a

German neurologist who discovered the area while studying patients who had similar symptomsto Broca's area patients but damage to a different part of their brain. Wernicke's aphasia is the

term for the disorder occurring upon damage to a patient's Wernicke's area.

Wernicke's aphasia does not only affect speech comprehension. People with Wernicke's aphasiaalso have difficulty recalling the names of objects, often responding with words that soundsimilar, or the names of related things, as if they are having a hard time recalling word

associations[citation needed]

.


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[edit] Pathology

A human brain showing frontotemporal lobar degeneration causing frontotemporal dementia

Clinically, death is defined as an absence of brain activity as measured by EEG. Injuries to the

brain tend to affect large areas of the organ, sometimes causing major deficits in intelligence,

memory, personality, and movement. Head trauma caused, for example, by vehicular or

industrial accidents, is a leading cause of death in youth and middle age. In many cases, moredamage is caused by resultant edema than by the impact itself. Stroke, caused by the blockage orrupturing of blood vessels in the brain, is another major cause of death from brain damage.

Other problems in the brain can be more accurately classified as diseases than as injuries.Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, motor neurone

disease, and Huntington's disease are caused by the gradual death of individual neurons, leadingto diminution in movement control, memory, and cognition.

Mental disorders, such as clinical depression, schizophrenia,bipolar disorderandpost-traumatic

stress disordermay involve particular patterns of neuropsychological functioning related to

various aspects of mental and somatic function. These disorders may be treated bypsychotherapy,psychiatric medication or social intervention and personal recovery work; theunderlying issues and associated prognosis vary significantly between individuals.

Some infectious diseases affecting the brain are caused by viruses andbacteria. Infection of the

meninges, the membrane that covers the brain, can lead to meningitis. Bovine spongiformencephalopathy (also known as "mad cow disease") is deadly in cattle and humans and is linked

toprions. Kuru is a similar prion-borne degenerative brain disease affecting humans. Both arelinked to the ingestion of neural tissue, and may explain the tendency in human and some non-

human species to avoid cannibalism. Viral or bacterial causes have been reported in multiplesclerosis and Parkinson's disease, and are established causes ofencephalopathy, and

encephalomyelitis.

Many brain disorders are congenital, occurring during development. Tay-Sachs disease, fragile X

syndrome, and Down syndrome are all linked to genetic and chromosomal errors. Many othersyndromes, such as the intrinsic circadian rhythm disorders, are suspected to be congenital as

well. Normal development of the brain can be altered by genetic factors, drug use, nutritionaldeficiencies, and infectious diseases duringpregnancy.


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Certain brain disorders are treated by neurosurgeons, while others are treated by neurologists andpsychiatrists.

Visualization of a diffusion tensor imaging (DTI) measurement of a human brain. Depicted are

reconstructed axon tracts that run through the mid-sagittal plane. Especially prominent are the U-

shaped fibers that connect the two hemispheres through the corpus callosum (the fibers come out of

the image plane and consequently bend towards the top) and the fiber tracts that descend toward the

spine (blue, within the image plane).

[edit] Metabolism

The brain consumes up to twenty percent of the energy used by the human body, more than any

other organ.[22]

Brain metabolism normally is completely dependent upon blood glucose as anenergy source, since fatty acids do not cross theblood-brain barrier.

[23]During times of low

glucose (such as fasting), the brain will primarily use ketone bodies for fuel with a smallerrequirement for glucose. The brain can also utilize lactate during exercise.[24] The brain does not

store any glucose in the form ofglycogen, in contrast, for example, to skeletal muscle.

general on brain

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