Related topics: brain cells
Human brain
hideThe human brain is the center of the human nervous system and is a highly complex organ. Enclosed in the cranium, it has the same general structure as the brains of other mammals, but is over three times as large as the brain of a mammal with an equivalent body size. 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 involved in executive functions such as self-control, planning, reasoning, and abstract thought. The portion of the brain devoted to vision is also greatly enlarged in humans.
Brain evolution, from the earliest shrewlike mammals through primates to hominids, is marked by a steady increase in encephalization, or the ratio of brain to body size. The human brain has been estimated to contain 50–100 billion (1011) neurons[citation needed], of which about 10 billion (1010) are cortical pyramidal cells.[citation needed] These cells pass signals to each other via approximately 100 trillion (1014)[citation needed] synaptic connections.
In spite of the fact that it is protected by the thick bones of the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood-brain barrier, the delicate nature of the human brain makes it susceptible to many types of damage and disease. The most common forms 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 rare because of the barriers that protect it, but is very serious when it occurs. More common are genetically based diseases[citation needed], such as Parkinson's disease, multiple sclerosis, and many others. 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 of such brain anomalies is not well understood.
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News tagged with human brain
Scientists discover 2 genes that drive aggressive brain cancers
Dec 23, 2009 |
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A team of Columbia scientists have discovered two genes that, when simultaneously activated, are responsible for the most aggressive forms of human brain cancer.
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Research backs theory on autism, schizophrenia
Nov 30, 2009 |
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(PhysOrg.com) -- New research by Simon Fraser University evolutionary biologist Bernard Crespi reinforces his theory that autism and schizophrenia are diametric or opposite conditions based on genes.
Research sheds new light on epilepsy
Nov 30, 2009 |
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Pioneering research using human brain tissue removed from people suffering from epilepsy has opened the door to new treatments for the disease.
Brain activity exposes those who break promises
Medicine & Health / Neuroscience
Dec 09, 2009 |
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Scientists from the University of Zurich have discovered the physiological mechanisms in the brain that underlie broken promises. Patterns of brain activity even enable predicting whether someone will break a promise. The ...
Protein link may be key to new treatment for aggressive brain tumor
Dec 22, 2009 |
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Biomedical researchers at the University of Central Florida have found a protein that could hold the key to treating one of the most common and aggressive brain tumors in adults.
Naked mole rats may hold clues to surviving stroke
Nov 30, 2009 |
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Blind, nearly hairless, and looking something like toothy, plump, pink fingers, naked mole rats may rank among nature's most maligned creatures, but their unusual physiology endears them to scientists.
Researchers discover how a brain hormone controls insect metamorphosis
Dec 03, 2009 |
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A team of University of Minnesota researchers have discovered how PTTH, a hormone produced by the brain, controls the metamorphosis of juvenile insects into adults.
Tumor-attacking virus strikes with 'one-two punch'
Dec 01, 2009 |
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Ohio State University cancer researchers have developed a tumor-attacking virus that both kills brain-tumor cells and blocks the growth of new tumor blood vessels.
New hope for diagnosis and treatment of intractable pediatric brain tumors
Dec 07, 2009 |
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Scientists have discovered oncogenes capable of driving growth of normal human brain stem cells in a highly malignant pediatric brain tumor. The research, published by Cell Press in the December issue of the journal Cancer Ce ...
Microcephaly genes associated with human brain size
Dec 21, 2009 |
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A group of Norwegian and American researchers have shown that common variations in genes associated with microcephaly - a neuro-developmental disorder in which brain size is dramatically reduced - may explain differences ...
Auditory illusion: How our brains can fill in the gaps to create continuous sound
Medicine & Health / Neuroscience
Nov 25, 2009 |
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It is relatively common for listeners to "hear" sounds that are not really there. In fact, it is the brain's ability to reconstruct fragmented sounds that allows us to successfully carry on a conversation in a noisy room. ...
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