Human Brain
A Human Brain is a human organ that is an animal brain.
- Context:
- It can be largely composed of Human Neural Cells.
- It can range from being an Infant Human Brain to being a Adolescent Human Brain to (typically) being an Adult Human Brain to being a Older-Person Human Brain.
- It can be modeled as a Biological Neural Network with approximately:
- [math]\displaystyle{ 2^{11} }[/math] (~100 billion) human brain neurons.
- [math]\displaystyle{ 10^{14} }[/math] (~100 billion) human brain synapses.
- [math]\displaystyle{ 2^{17} }[/math] Neural Network Edges.
- [math]\displaystyle{ 2^{12} }[/math] (~1000 billion) glial cells.
- It can be divided into Human Brain Regions, such as a human forebrain, human midbrain and human hindbrain.
- It can be largely composed of Human Neural Cells.
- It can achieve approximately 10 Exaflops.
- It can consume 20 Watts (0.5 Exa-Flops per watt).
- It can way approximately 1.2–1.4 kg (2.6–3.1 lb), or about 2% of the total body weight
- It can have a volume of approximately 1260 cm3 in men and 1130 cm3 in women,
- It can be modeled by an Artificial Human Brain (an artificial brain possibly based on a recurrent network).
- Example(s):
- Albert Einstein's Brain in 1879, in 1905, in 1955, in 2015.
- …
- Counter-Example(s):
- a Human Eye Retina.
- a Chimpanzee Brain.
- a Mouse Brain.
- a C. elegans Brain (with 302 neuron cells)
- See: Consciousness, Exascale Computer.
References
2017
- (Wikipedia, 2017) ⇒ https://en.wikipedia.org/wiki/human_brain Retrieved:2017-6-27.
- The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head. The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lobes. The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, a motor and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are associated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected by nerve tracts, the largest being the corpus callosum.
The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by pairs of tracts. Within the cerebrum is the ventricular system, consisting of four interconnected ventricles in which cerebrospinal fluid is produced and circulated. Underneath the cerebral cortex are several important structures, including the thalamus, the epithalamus, the pineal gland, the hypothalamus, the pituitary gland, and the subthalamus; the limbic structures, including the amygdala and the hippocampus; the claustrum, the various nuclei of the basal ganglia; the basal forebrain structures, and the three circumventricular organs. The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses. Neurons form elaborate neural networks of neural pathways and circuits. The whole circuitry is driven by the process of neurotransmission.
The brain is protected by the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood–brain barrier. However, the brain is still susceptible to damage, disease, and infection. Damage can be caused by trauma, or a loss of blood supply known as a stroke. The brain is susceptible to degenerative disorders, such as Parkinson's disease, dementias including Alzheimer's disease, and multiple sclerosis. Psychiatric conditions, including schizophrenia and clinical depression, are thought to be associated with brain dysfunctions. The brain can also be the site of tumours, both benign and malignant; these last mostly originate from other sites in the body.
The study of the anatomy of the brain is neuroanatomy, while the study of its function is neuroscience. A number of techniques are used to study the brain. Specimens from other animals, which may be examined microscopically, have traditionally provided much information. Medical imaging technologies such as functional neuroimaging, and electroencephalography (EEG) recordings are important in studying the brain. The medical history of people with brain injury has provided insight into the function of each part of the brain.
- The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head. The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lobes. The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, a motor and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are associated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected by nerve tracts, the largest being the corpus callosum.
2015
- (Wikipedia, 2015) ⇒ http://en.wikipedia.org/wiki/human_brain#Structure 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. 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.
- 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. 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.
2015
- (Frankland & Greene, 2015) ⇒ Steven M. Frankland, and Joshua D. Greene. (2015). “An Architecture for Encoding Sentence Meaning in Left Mid-superior Temporal Cortex.” In: Proceedings of the National Academy of Sciences, 112(37).
- QUOTE: Human brains flexibly combine the meanings of words to compose structured thoughts. For example, by combining the meanings of “bite,” “dog,” and “man,” we can think about a dog biting a man, or a man biting a dog.
2014
- http://en.wikipedia.org/wiki/List_of_regions_in_the_human_brain
- Anatomical regions of the brain are listed vertically, following hierarchies that are standard in neuroanatomy. Functional, connective, and developmental regions are listed horizontally in parentheses where appropriate.
2014
- http://www.theatlantic.com/health/archive/2014/11/the-brain-makes-its-own-ghosts/382527/
- QUOTE: … studied the brains of 12 patients with neurological disorders (mainly epilepsy) who had experienced FOP, and found lesions in three regions of their brains: the insular cortex, frontoparietal cortex, and temporoparietal cortex. These areas deal with self-awareness, movement, and spatial positioning, suggesting that when sensorimotor signals get confused, people can feel presences that aren’t there. …
2014
- (Schmidhuber, 2014) ⇒ Jürgen Schmidhuber. (2014). “Jürgen Schmidhuber's page on Recurrent Neural Networks."
- QUOTE: The human brain is a recurrent neural network (RNN): a network of neurons with feedback connections.
- http://www.basicknowledge101.com/subjects/brain.html
- 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.
2013
- http://en.wikipedia.org/wiki/List_of_regions_in_the_human_brain#Forebrain_.28prosencephalon.29
- Diencephalon.
- Third ventricle.
- Hypothalamus (limbic system) (HPA axis)
- Anterior
- Medial area
- Parts of preoptic area
- Medial preoptic nucleus
- Suprachiasmatic nucleus.
- Paraventricular nucleus.
- Supraoptic nucleus (mainly)
- Anterior hypothalamic nucleus
- Parts of preoptic area
- Lateral area
- Parts of preoptic area
- Lateral preoptic nucleus
- Anterior part of Lateral nucleus
- Part of supraoptic nucleus
- Parts of preoptic area
- Other nuclei of preoptic area.
- median preoptic nucleus
- periventricular preoptic nucleus
- Medial area
- Tuberal
- Medial area
- Lateral area
- Tuberal part of Lateral nucleus
- Lateral tuberal nuclei.
- Posterior
- Medial area
- Mammillary nuclei (part of mammillary bodies)
- Posterior nucleus.
- Lateral area
- Posterior part of Lateral nucleus.
- Medial area
- Optic chiasm.
- Subfornical organ.
- Periventricular nucleus.
- Pituitary stalk.
- Tuber cinereum.
- Tuberal nucleus
- Tuberomamillary nucleus.
- Tuberal region.
- Mammillary bodies.
- Mammillary nucleus.
- Anterior
- Subthalamus(HPA axis)
- Pituitary gland (HPA axis)
- Telencephalon (cerebrum) Cerebral hemispheres.
- White matter.
- Subcortical
- Rhinencephalon (paleopallium)
- Cerebral cortex (neopallium)
- Frontal lobe.
- Cortex
- Primary motor cortex (Precentral gyrus, M1)
- Supplementary motor cortex.
- Premotor cortex.
- Prefrontal cortex.
- Gyri.
- Brodmann areas: 4, 6, 8, 9, 10, 11, 12, 24, 25, 32, 33, 44, 45, 46, 47.
- Cortex
- Parietal lobe.
- Occipital lobe.
- Cortex
- Primary visual cortex (V1)
- V2.
- V3.
- V4.
- V5/MT.
- Cortex
- Frontal lobe.
-
- Temporal lobe.
- Insular cortex.
- Cingulate cortex.
2009
- (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.