Alzheimer's disease & dementia

Periodontal disease bacteria may kick-start Alzheimer's

Long-term exposure to periodontal disease bacteria causes inflammation and degeneration of brain neurons in mice that is similar to the effects of Alzheimer's disease in humans, according to a new study from researchers at ...

Alzheimer's disease & dementia

Moving more in old age may protect brain from dementia

Older adults who move more than average, either in the form of daily exercise or just routine physical activity such as housework, may maintain more of their memory and thinking skills than people who are less active than ...

Alzheimer's disease & dementia

Leaky blood-brain barrier linked to Alzheimer's disease

Researchers using contrast-enhanced MRI have identified leakages in the blood-brain barrier (BBB) of people with early Alzheimer's disease (AD), according to a new study published online in the journal Radiology. The results ...

Medical research

Revealed: Brain 'switch' tells body to burn fat after a meal

Scientists at Monash University's Biomedicine Discovery Institute have found a mechanism by which the brain coordinates feeding with energy expenditure, solving a puzzle that has previously eluded researchers and offering ...

Alzheimer's disease & dementia

New study suggests viral connection to Alzheimer's disease

Of the major illnesses facing humanity, Alzheimer's disease (AD) remains among the most pitiless and confounding. Over a century after its discovery, no effective prevention or treatment exists for this progressive deterioration ...

Neuroscience

The brain needs cleaning to stay healthy

Research led by the Achucarro Basque Center for Neuroscience, the University of the Basque Country (UPV/EHU), and the Ikerbasque Foundation has revealed the mechanisms that keep the brain clean during neurodegenerative diseases.

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Human brain

The 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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