How many neurons are in the average human brain? Toast?


According to the Chicago: World Book of 2001 the human brain has from 10 billion to 100 billion neurons.Wow!

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neurons Anatomy Biology Neuroscience Brain

The nervous system is the part of an animal's body that coordinates the voluntary and involuntary actions of the animal and transmits signals between different parts of its body. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In most types of animals it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS contains the brain and spinal cord. The PNS consists mainly of nerves, which are long fibers that connect the CNS to every other part of the body. The PNS includes motor neurons, mediating voluntary movement, the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions, and the enteric nervous system, a semi-independent part of the nervous system whose function is to control the gastrointestinal system.

At the cellular level, the nervous system is defined by the presence of a special type of cell, called the neuron, also known as a "nerve cell". Neurons have special structures that allow them to send signals rapidly and precisely to other cells. They send these signals in the form of electrochemical waves traveling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal from a neuron may be excited, inhibited, or otherwise modulated. The connections between neurons form neural circuits that generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support.

Organs Neuron

The human brain has the same general structure as the brains of other mammals, but is larger than any other in relation to body size. Large animals such as whales and elephants have larger brains in absolute terms, but when measured using the encephalization quotient which compensates for body size, the human brain is almost twice as large as the brain of the bottlenose dolphin, and three times as large as the brain of a chimpanzee. Much of the expansion comes from the part of the brain called the cerebral cortex, especially the frontal lobes, which are associated with executive functions such as self-control, planning, reasoning, and abstract thought. The portion of the cerebral cortex devoted to vision is also greatly enlarged in humans.

The human cerebral cortex is a thick layer of neural tissue that covers most of the brain. This layer is folded in a way that increases the amount of surface that can fit into the volume available. The pattern of folds is similar across individuals, although there are many small variations. The cortex is divided into four "lobes", called the frontal lobe, parietal lobe, temporal lobe, and occipital lobe. (Some classification systems also include a limbic lobe and treat the insular cortex as a lobe.) Within each lobe are numerous cortical areas, each associated with a particular function such as vision, motor control, language, etc. The left and right sides of the cortex are broadly similar in shape, and most cortical areas are replicated on both sides. Some areas, though, show strong lateralization, particularly areas that are involved in language. In most people, the left hemisphere is "dominant" for language, with the right hemisphere playing only a minor role. There are other functions, such as spatiotemporal reasoning, for which the right hemisphere is usually dominant.

Spindle neurons, also called von Economo neurons (VENs), are a specific class of neurons that are characterized by a large spindle-shaped soma, gradually tapering into a single apical axon in one direction, with only a single dendrite facing opposite. Whereas other types of cells tend to have many dendrites, the polar shaped morphology of spindle neurons is unique. They are found in two very restricted regions in the brains of hominids – the family of species comprising humans and other great apes – the anterior cingulate cortex (ACC) and the fronto-insular cortex (FI). Recently they have been discovered in the dorsolateral prefrontal cortex of humans. Spindle cells are also found in the brains of the humpback whales, fin whales, killer whales, sperm whales, bottlenose dolphin, Risso’s dolphin, beluga whales, and the African and Asian elephants. The name von Economo neuron comes from their discoverer, Constantin von Economo (1876–1931) who described them in 1929.

Whole brain emulation or "mind uploading" (sometimes called "mind copying" or "mind transfer") is the hypothetical process of copying or transferring a conscious mind from a brain to another storage medium by scanning and mapping a biological brain in detail and copying its information and computational state into a computer system or another computational device. The computer would have to run a simulation model so faithful to the original that it would behave in essentially the same way as the original brain, or for all practical purposes, indistinguishably. The simulated mind is assumed to be part of a virtual reality simulated world, supported by an anatomic 3D body simulation model. Alternatively, the simulated mind could be assumed to reside in a computer inside (or connected to) a humanoid robot or a biological body, replacing its brain.

Whole brain emulation is discussed by some futurists as a "logical endpoint" of the topical computational neuroscience and neuroinformatics fields, both about brain simulation for medical research purposes. It is discussed in artificial intelligence research publications as an approach to strong AI. Among some futurists and within the transhumanist movement it is an important proposed life extension technology, originally suggested in biomedical literature in 1971. It is a central conceptual feature of numerous science fiction novels and films.

Science of drugs including their origin, composition, pharmacokinetics,
pharmacodynamics, therapeutic use, and toxicology.

Pharmacology (from Greek φάρμακον, pharmakon, "poison" in classic Greek; "drug" in modern Greek; and -λογία, -logia "study of", "knowledge of") is the branch of medicine and biology concerned with the study of drug action, where a drug can be broadly defined as any man-made, natural, or endogenous (within the body) molecule which exerts a biochemical and/or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.

Finance is the allocation of assets and liabilities over time under conditions of certainty and uncertainty. A key point in finance is the time value of money, which states that a unit of currency today is worth more than the same unit of currency tomorrow. Finance aims to price assets based on their risk level, and expected rate of return. Finance can be broken into three different sub categories: public finance, corporate finance and personal finance.



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