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Encyclopedia > Neurobiology
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'Neurobiology' is the study of cells of the nervous system and the organization of these cells into functional circuits that process information and mediate behavior.[1] It is a subdiscipline of both biology and neuroscience. Neurobiology differs from neuroscience, a much broader field that is concerned with any scientific study of the nervous system. Neurobiology should also not be confused with other subdisciplines of neuroscience such as computational neuroscience, cognitive neuroscience, behavioral neuroscience, biological psychiatry, neurology, and neuropsychology despite the overlap with these subdisciplines. Scientists that study neurobiology are called neurobiologists. Image File history File links Portal. ... Image File history File links Neuro_logo. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... The Human Nervous System The nervous system of an animal coordinates the activity of the muscles, monitors the organs, constructs and also stops input from the senses, and initiates actions. ... This article or section does not adequately cite its references or sources. ... Drawing of the cells in the chicken cerebellum by S. Ramón y Cajal Neuroscience is a field that is devoted to the scientific study of the nervous system. ... Computational Neuroscience is an interdisciplinary science that links the diverse fields of neuroscience, electrical engineering, computer science, physics and applied mathematics together. ... The field of cognitive neuroscience concerns the scientific study of the neural mechanisms underlying cognition and is a branch of neuroscience. ... Behavioral neuroscience approach. ... Biological psychiatry, or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system. ... Neurology is a branch of medicine dealing with disorders of the nervous system. ... Neuropsychology is a branch of psychology and neurology that aims to understand how the structure and function of the brain relate to specific psychological processes. ... Neurobiologist is a life scientist who is devoted to the study of neurobiology. ...

Contents

Neurons and Glial Cells

Main articles: neuron, glial cell Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ... This article or section does not cite its references or sources. ...

stained neuron
stained neuron

Neurons are cells that are specialized to receive, propagate, and transmit electrochemical impulses. In the human brain alone, there are over a hundred billion neurons. Neurons are diverse with respect to morphology and function. Thus, not all neurons correspond to the stereotypical motor neuron with dendrites and myelinated axons that conduct action potentials. Some neurons such as photoreceptors, for example, do not have myelinated axons that conduct action potentials. Other unipolar neurons found in invertebrates do not even have distinguishing processes such as dendrites. Moreover, the distinctions based on function between neurons and other cells such as cardiac and muscle cells are not helpful. Thus, the fundamental difference between a neuron and a nonneuronal cell is a matter of degree. Image File history File linksMetadata Download high-resolution version (864x1013, 59 KB) Neuron from Chicken embryo photographed with conical microscope after being dyed. ... Image File history File linksMetadata Download high-resolution version (864x1013, 59 KB) Neuron from Chicken embryo photographed with conical microscope after being dyed. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... In biology, a dendrite is a slender, typically branched projection of a nerve cell, or neuron, which conducts the electrical stimulation received from other cells to the body or soma of the cell from which it projects. ... Photoreceptors are light-sensitive proteins involved in the function of photoreceptor cells. ...


Another major class of cells found in the nervous system are glial cells. Despite the abundance of glial cells relative to neurons in the nervous system (there are ten glial cells for every single neuron), glial cells are only recently beginning to receive attention from neurobiologists for being involved not just in nourishment and support of neurons, but also in modulating synapses. For example, Schwann cells, a type of glial cells found in the peripheral nervous system, modulate synaptic connections between the presynaptic terminal from a motor neuron and endplate muscle fiber in the neuromuscular junction.


Neuronal Function

One prominent characteristic of many neurons is excitability. Neurons generate electrical impulses or changes in voltage of two types: graded potentials and action potentials. Graded potentials occur when the membrane potential depolarizes and hypolarizes in a graded fashion relative to the amount of stimulus that is applied to the neuron. An action potential on the other hand is an all-or-none electrical impulse. Despite being slower than graded potentials, action potentials have the advantage of traveling long distances in axons with little or no decrement. Much of the current knowledge of action potentials comes from squid axon experiments by Sir Alan Lloyd Hodgkin and Sir Andrew Fielding Huxley. Sir Alan Lloyd Hodgkin (February 5, 1914 - December 20, 1998) was a British physiologist and biophysicist, who won the 1963 Nobel Prize in Physiology or Medicine for his work with Andrew Fielding Huxley on the basis of nerve action potentials, the electrical impulses that enable the activity of an organism... Andrew Huxley at Trinity College, Cambridge, July 2005 Family tree Sir Andrew Fielding Huxley, OM, FRS (born 22 November 1917, Hampstead, London) is an English physiologist and biophysicist, who won the 1963 Nobel Prize in Physiology or Medicine for his work with Alan Lloyd Hodgkin on the basis of nerve...


Action Potential

"Current Clamp" is a common technique in electrophysiology. This is a whole cell current clamp recording of a neuron firing a train of action potentials due to it being depolarized by current injection
"Current Clamp" is a common technique in electrophysiology. This is a whole cell current clamp recording of a neuron firing a train of action potentials due to it being depolarized by current injection

The Hodgkin-Huxley Model of an action potential in the squid giant axon has been the basis for much of the current understanding of the ionic bases of action potentials. Briefly, the model states that the generation of an action potential is detemined by two ions: Na+ and K+. An action potential can be divided into several sequential phases: threshold, rising phase, falling phase, undershoot phase, and recovery. Following several local graded depolarizations of the membrane potential, the threshold of excitation is reached, voltage-gated sodium channels are activated, which leads to an influx of Na+ ions. As Na+ ions enter the cell, the membrane potential is further depolarized, and more voltage-gated sodium channels are activated. Such a process is also known as a positive-feedback loop. As the rising phase reaches its peak, voltage-gated Na+ channels are inactivated whereas voltage-gated K+ channels are activated, resulting in a net outward movement of K+ ions, which repolarizes the membrane potential towards the resting membrane potential. Repolarization of the membrane potential continues, resulting in an undershoot phase or absolute refractory period. The undershoot phase occurs because unlike voltage-gated sodium channels, voltage-gated potassium channels inactivate much more slowly. Nevertheless, as more voltage-gated K+ channels become inactivated, the membrane potential recovers to its normal resting steady state. Image File history File links Download high-resolution version (840x531, 7 KB) A whole-cell current-clamp recording I made of a Substantia Nigra Pars Reticulata neuron. ... Image File history File links Download high-resolution version (840x531, 7 KB) A whole-cell current-clamp recording I made of a Substantia Nigra Pars Reticulata neuron. ... The Hodgkin-Huxley Model is a set of non-linear ordinary differential equations, named after Alan Lloyd Hodgkin and Andrew Huxley, that approximates the electrical characteristics of excitable cells such as neurons and cardiac myocytes. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ...


Structure and Formation of Synapses

Illustration of the major elements in a prototypical synapse. Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical impulses into chemical signals.
Illustration of the major elements in a prototypical synapse. Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical impulses into chemical signals.

Neurons communicate with one another via synapses. Synapses are specialized junctions between two cells in close apposition to one another. In a synapse, the neuron that sends the signal is the presynaptic neuron and the target cell receives that signal is the postsynaptic neuron or cell. Synapses can be either electrical or chemical. Electrical synapses are characterized by the formation of gap junctions that allow ions and other organic compound to instantaneously pass from one cell to another[2]. Chemical synapses are characterized by the presynaptic release of neurotransmitters that diffuse across a synaptic cleft to bind with postsynaptic receptors. A neurotransmitter is a chemical messenger that is synthesized within neurons themselves and released by these same neurons to communicate with their postsynaptic target cells. A receptor is a transmembrane protein molecule that a neurotransmitter or drug binds. Chemical synapses are slower than electrical synapses. Image File history File links Download high-resolution version (859x564, 69 KB)I created this image. ... Image File history File links Download high-resolution version (859x564, 69 KB)I created this image. ... Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ... An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... The term Dendrite stems from the Greek word dendron (literally “tree”), and typically refers to the branched projections of a neuron that act to conduct the electrical stimulation received from other cells to and from the cell body, or soma of the neuron from which the dendrites project. ... A. A schematic view of an idealized action potential illustrates its various phases as the action potential passes a point on a cell membrane. ... Chemical structure of D-Aspartic Acid, a common Amino Acid neurotransmitter. ... Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical signals into chemical ones. ... Communication is the process of exchanging information usually via a common system of symbols. ...


Neurotransmitter Transporters, Receptors, and Signaling Mechanisms

After neurotransmitters are synthesized, they are packaged and stored in vesicles. These vesicles are pooled together in terminal boutons of the presynaptic neuron. When there is a change in voltage in the terminal bouton, voltage-gated calcium channels embedded in the membranes of these boutons become activated. These allow Ca2+ ions to diffuse through these channels and bind with synaptic vesicles within the terminal buttons. Once bounded with Ca2+, the vesicles dock and fuse with the presynaptic membrane, and release neurotransmitters into the synaptic cleft by a process known as exocytosis. The neurotransmitters then diffuse across the synaptic cleft and binds to postsynaptic receptors embedded on the postsynaptic membrane of another neuron. There are two families of receptors: ionotropic and metabotropic receptors. Ionotropic receptors are a combination of a receptor and an ion channel. When ionotropic receptors are activated, certain ion species such as Na+ to enter the postsynaptic neuron, which depolarizes the postsynaptic membrane. If more of the same type of postsynaptic receptors are activated, then more Na+ will enter the postsynaptic membrane and depolarize cell. Metabotropic receptors on the other hand activate second messenger cascade systems that result in the opening of ion channel located some place else on the same postsynaptic membrane. Although slower than ionotropic receptors that function as on-and-off switches, metabotropic receptors have the advantage of amplifying the signal from a single transmitter. This page is currently under construction. ...


Postsynaptic depolarizations can be either excitatory or inhibitory. Those that are excitatory are referred to as excitatory postsynaptic potential (EPSP). Alternatively, some postsynaptic receptors allow Cl- ions to enter the cell or K+ ions to leave the cell, which results in an inhibitory postsynaptic potential (IPSP). If the EPSP is dominant, the threshold of excitation in the postynaptic neuron may be reached, resulting in the generation and propagation of an action potential in the postynaptic neuron. In neuroscience, an excitatory postsynaptic potential (EPSP) is a temporary increase in postsynaptic membrane potential caused by the flow of positively charged ions into the postsynaptic cell. ... Excitatory Postsynaptic Potential is generally abbreviated to Much information is available under the heading synapse, but this is a different concept. ... Inhibitory Postsynaptic Potential is commonly abbreviated to Impulses are transmitted from neuron to neuron by the release of a chemical transmitter across synaptic clefts from the synaptic vesicles along the axon to the postsynaptic receptors of another neuron. ... Inhibitory Postsynaptic Potential is commonly abbreviated to Currently there is more information available under the heading synapse. ...


Synaptic Plasticity

Synaptic plasticity is the process whereby strengths of synaptic connections are altered. For example, long-term changes in synaptic connection may result in more postynaptic receptors being embedded in the postsynaptic membrane, resulting in the strengthening of the synapse. Synaptic plasticity is also found to be the neural mechanism that underlies learning and memory. In neuroscience, synaptic plasticity is the ability of the connection, or synapse, between two neurons to change in strength. ...


Sensory Systems

Gray's FIG. 722– Scheme showing central connections of the optic nerves and optic tracts.
Gray's FIG. 722– Scheme showing central connections of the optic nerves and optic tracts.

The auditory system is a sensory system for the sense of hearing. It consists of the outer ear, the middle ear, and the inner ear. Image File history File links Gray722. ... Image File history File links Gray722. ... An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy after Henry Gray, is an anatomy textbook widely regarded as a classic work on human anatomy. ... MRI scan of human eye showing optic nerve. ... The auditory system is the sensory system for the sense of hearing. ...


The olfactory system is the sensory system used for olfaction. The accessory olfactory system senses pheromones. The olfactory system is often spoken of along with the gustatory system as the chemosensory senses because both transduce chemical signals into perception. Linda B. Buck and Richard Axel won the 2004 Nobel Prize in Physiology or Medicine for their work on the olfactory system. The olfactory system is the sensory system used for olfaction. ...


The visual system is the part of the nervous system which allows organisms to see. It interprets the information from visible light to build a representation of the world surrounding the body. The visual system has the complex task of (re)constructing a three dimensional world from a two dimensional projection of that world. Note that different species are able to see different parts of the light spectrum; for example, some can see into the ultraviolet, while others can see into the infrared. The visual system is the part of the nervous system which allows organisms to see. ...


Neural Development

Neural development is the process whereby the nervous system grows and develops. Aside from the primitive gut, the nervous system is the first organ system to develop and the last system to finish. Development of the nervous system begins when the ectoderm thickens to form a neural plate. The neural plate in turns thickens to form the neural tube, which then twists, turns and kinks to form the three primary brain vesicles and five secondary brain vesicles. Within this neural tube, totipotent cells migrate and differentiate into neurons and glial cells. The neural plate will form the neural tube The study of neural development draws on both neuroscience and developmental biology to describe the cellular and molecular mechanisms by which complex nervous systems emerge during embryonic development and throughout life. ...


References

  1. ^ Shepard, G. M. (1994). Neurobiology. 3rd Ed. Oxford University Press. ISBN 0-19-508843-3
  2. ^ Martin, A. R., Wallace, B. G., Fuchs, P. A. & Nicholls, J. G. (2001). From Neuron to Brain: A Cellular and Molecular Approach to the Function of the Nervous System. 4th Ed. Sinauer Associates. ISBN 0-87893-439-1

Neuroscience subfields: Drawing of the cells in the chicken cerebellum by S. Ramón y Cajal Neuroscience is a field that is devoted to the scientific study of the nervous system. ...

Neurobiology | Cognitive Neuroscience | Computational Neuroscience | Neural Engineering | Neuroanatomy | Neurochemistry | Neuroendocrinology |Neuroimaging | Neurolinguistics | Neurology | Neuromonitoring | Neuropharmacology | Neurophysiology | Neuropsychology | Neuropsychiatry | Psychopharmacology | Systems Neuroscience | Molecular Cellular Cognition

Psychology subfields: The field of cognitive neuroscience concerns the scientific study of the neural mechanisms underlying cognition and is a branch of neuroscience. ... Computational Neuroscience is an interdisciplinary science that links the diverse fields of neuroscience, electrical engineering, computer science, physics and applied mathematics together. ... It has been suggested that Neuro cybernetics be merged into this article or section. ... Neuroanatomy is the anatomy of the nervous system. ... Neurochemistry is a branch of neuroscience that is heavily devoted to the study of neurochemicals. ... Neuroendocrinology is the study of the interactions between the nervous system and the endocrine system. ... Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function, or pharmacology of the brain. ... Neurolinguistics is the science concerned with the human brain mechanisms underlying the comprehension, production, and abstract knowledge of language, be it spoken, signed, or written. ... Neurology is a branch of medicine dealing with disorders of the nervous system. ... The scientific practice of neuromonitoring takes place in the surgical suite (OR). ... Neuropharmacology is the branch of health science concerned with the study of drugs on the nervous system. ... Neurophysiology is a part of physiology as a science, which is concerned with the study of the nervous system. ... Neuropsychology is a branch of psychology and neurology that aims to understand how the structure and function of the brain relate to specific psychological processes. ... Neuropsychiatry is the branch of medicine dealing with mental disorders attributable to diseases of the nervous system. ... Psychopharmacology is the study of the effects of any psychoactive drug that acts upon the mind by affecting brain chemistry. ... Systems neuroscience is a subdicipline of neuroscience which studies the neural circuit function, most commonly in awake, behaving intact organisms. ... Key goals of studies in the field of molecular cellular cognition (MCC) include the derivation of explanations of cognitive processes that integrate molecular, cellular, and behavioral mechanisms, and finding mechanism and treatments for cognitive disorders. ... Psychology is an academic and applied discipline involving the scientific study of mental processes, emotion, personality, behavior, and relationships. ...

Cognitive Psychology | Cognitive Neuroscience | Computational Psychology | Biological Psychology | Mathematical Psychology | Neuroimaging | Psycholinguistics | Psychophysiology | Neuropsychology | Neuropsychiatry | Psychopharmacology | Systems Neuroscience | Developmental Psychology | Social Psychology | Clinical Psychology | Evolutionary Psychology

Cognitive Psychology is the school of psychology that examines internal mental processes such as problem solving, memory, and language. ... The field of cognitive neuroscience concerns the scientific study of the neural mechanisms underlying cognition and is a branch of neuroscience. ... Biological psychology is the scientific study of the biological bases of behavior and mental states. ... Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function, or pharmacology of the brain. ... Psycholinguistics or psychology of language is the study of the psychological and neurobiological factors that enable humans to acquire, use, and understand language. ... Psychophysiology is the science of understanding the link between psychology and physiology. ... Neuropsychology is a branch of psychology and neurology that aims to understand how the structure and function of the brain relate to specific psychological processes. ... Neuropsychiatry is the branch of medicine dealing with mental disorders attributable to diseases of the nervous system. ... Psychopharmacology is the study of the effects of any psychoactive drug that acts upon the mind by affecting brain chemistry. ... Systems neuroscience is a subdicipline of neuroscience which studies the neural circuit function, most commonly in awake, behaving intact organisms. ... This article or section is incomplete and may require expansion and/or cleanup. ... The scope of social psychological research. ... The Greek letter Psi is often used as a symbol of psychology. ... Evolutionary psychology (abbreviated ev-psych or EP) is a theoretical approach to psychology that attempts to explain certain mental and psychological traits—such as memory, perception, or language—as evolved adaptations, i. ...

External links

  • Journal of Neurobiology — Original research articles on the nervous system

  Results from FactBites:
 
Neurobiology - Wikipedia, the free encyclopedia (1091 words)
Neurobiology is a branch of biology that is involved in the study of nervous systems of all animals from a biological and evolutionary perspective.
It is also subdiscipline of neuroscience, a much broader field that is concerned with any scientific study of the nervous system.
Neurobiology should not be confused however, with other subdisciplines of neuroscience such as computational neuroscience, cognitive neuroscience, behavioral neuroscience, biological psychiatry, neurology, and neuropsychology.
Neurobiology News Page (417 words)
The Neurobiology Graduate Program's mission is to train a new generation of neuroscientists who have the breadth of training in the fundamentals of modern neurobiological research ranging from molecular to systems' approaches and depth of training in particular areas so as to enable them to become leading contributors to the health-related brain research enterprise.
The Neurobiology laboratories are well-equipped, state of the art facilities including full instrumentation for patch-clamp electrophysiology, high resolution cellular imaging, FRET, cell culture, a broad range of recombinant technologies including "gene gun,"viral transfection and transgenic approaches, molecular biology, and electron, single and two-photon laser scanning confocal microscopy.
Neurobiology is a highly interdisciplinary endeavor and this is reflected in the faculty's individual laboratories.
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