Human Brain

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A Human Brain is a human organ that is an animal brain.




  • (Wikipedia, 2015) ⇒ Retrieved:2015-10-4.
    • The adult human brain weighs on average about 1.3-1.4 kg, or about 2% of total body weight, with a volume of around 1130 cubic centimetres (cm3) in women and 1260 cm3 in men, although there is substantial individual variation. Neurological differences between the sexes have not been shown to correlate in any simple way with IQ or other measures of cognitive performance.[1] The human brain is composed of neurons, glial cells, and blood vessels. The number of neurons, according to array tomography, has been shown to be on average about 86 billion in the adult male human brain with a roughly equal number of non-neuronal cells. Out of these, 16 billion (or 19% of all brain neurons) are located in the cerebral cortex (including subcortical white matter), 69 billion (or 80% of all brain neurons) are in the cerebellum, and fewer than 1% of all brain neurons are located in the rest of the brain. The cerebral hemispheres (the cerebrum) form the largest part of the human brain and are situated above other brain structures. They are covered with a cortical layer (the cerebral cortex) which has a convoluted topography. Underneath the cerebrum lies the brainstem, resembling a stalk on which the cerebrum is attached. At the rear of the brain, beneath the cerebrum and behind the brainstem, is the cerebellum, a structure with a horizontally furrowed surface, the cerebellar cortex, that makes it look different from any other brain area. The same structures are present in other mammals, although they vary considerably in relative size. As a rule, the smaller the cerebrum, the less convoluted the cortex. The cortex of a rat or mouse is almost perfectly smooth. The cortex of a dolphin or whale, on the other hand, is more convoluted than the cortex of a human.

      The living brain is very soft, having a consistency similar to soft gelatin or soft tofu. Although referred to as grey matter, the live cortex is pinkish-beige in color and slightly off-white in the interior.





  • (Schmidhuber, 2014) ⇒ Jürgen Schmidhuber. (2014). “Jürgen Schmidhuber's page on Recurrent Neural Networks."
    • QUOTE: The Human Brain weighs about 3 Pounds, which is 2% of a person's weight, but consumes as much as 25 percent of our body’s Oxygen, burns 20% of our total Calories each day, with Glucose being the main energy source for the brain that runs on around 12 watts of power, which is a fifth of the power required by a standard 60 watt light bulb. The Brain has 400 miles of Capillaries, 86 Billion Microscopic Neurons in constant Synaptic communication, making 10 quadrillion calculations every second. Each neuron is like a tiny branching tree, whose limbs reach out and touch other neurons making between 5,000 and 10,000 connections with other neurons, that’s more than 500 trillion connections performing a dazzling array of complex mental processes every second, geared to generating and regulating our sensations and perceptions, how we reason, how we think, our emotions, our mental images, our attention span, learning, and our memory which is essentially a Pattern of connections between neurons.



  • (Azevedo et al., 2009) ⇒ Frederico AC Azevedo, Ludmila RB Carvalho, Lea T. Grinberg, José Marcelo Farfel, Renata EL Ferretti, Renata EP Leite, Roberto Lent, and Suzana Herculano‐Houzel. (2009). “Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled‐up primate brain.” In: Journal of Comparative Neurology 513,(5).
    • QUOTE: The human brain is often considered to be the most cognitively capable among mammalian brains and to be much larger than expected for a mammal of our body size. Although the number of neurons is generally assumed to be a determinant of computational power, and despite the widespread quotes that the human brain contains 100 billion neurons and ten times more glial cells, the absolute number of neurons and glial cells in the human brain remains unknown. Here we determine these numbers by using the isotropic fractionator and compare them with the expected values for a human-sized primate. We find that the adult male human brain contains on average 86.1 +/- 8.1 billion NeuN-positive cells ("neurons") and 84.6 +/- 9.8 billion NeuN-negative ("nonneuronal") cells. With only 19% of all neurons located in the cerebral cortex, greater cortical size (representing 82% of total brain mass) in humans compared with other primates does not reflect an increased relative number of cortical neurons. The ratios between glial cells and neurons in the human brain structures are similar to those found in other primates, and their numbers of cells match those expected for a primate of human proportions. These findings challenge the common view that humans stand out from other primates in their brain composition and indicate that, with regard to numbers of neuronal and nonneuronal cells, the human brain is an isometrically scaled-up primate brain.

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