Related topics: brain · genes · brain cells · neurons · neuroscientists

How human brain development diverged from great apes

Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Institute of Molecular and Clinical Ophthalmology Basel, and ETH Zurich, Switzerland, have presented new insights into the development ...

Human intelligence: have we reached the limit of knowledge?

Despite huge advances in science over the past century, our understanding of nature is still far from complete. Not only have scientists failed to find the Holy Grail of physics—unifying the very large (general relativity) ...

Implanted memories teach birds a song

A father holds up his newborn, their faces only inches apart, and slowly repeats the syllables "da" and "dee." After months of hearing these sounds, the baby begins to babble and gradually "da da da" is refined to the word ...

Golden Ratio observed in human skulls

The Golden Ratio, described by Leonardo da Vinci and Luca Pacioli as the "Divine Proportion," is an infinite number often found in nature, art and mathematics. It's a pattern in pinecones, seashells, galaxies and hurricanes.

Growing a smarter model for brain research in space

Researchers studying neurological diseases face several daunting challenges. For one thing, these conditions may take years or even decades to develop. On top of that, experimenting on the brains of healthy human beings simply ...

Pros and cons of genetic scissors

Crispr technology has greatly facilitated gene editing. Associate Professor Thorsten Müller from Ruhr-Universität Bochum and Dr. Hassan Bukhari from Harvard Medical School discuss its pros and cons in a review article in ...

Brain waves detected in mini-brains grown in a dish

Scientists have created miniature brains from stem cells that developed functional neural networks. Despite being a million times smaller than human brains, these lab-grown brains are the first observed to produce brain waves ...

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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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