What is Neuron: Definition and 39 Discussions

A neuron or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue in all animals except sponges and placozoa. Plants and fungi do not have nerve cells.
Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. A group of connected neurons is called a neural circuit.
A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is usually compact. The axon and dendrites are filaments that extrude from it. Dendrites typically branch profusely and extend a few hundred micrometers from the soma. The axon leaves the soma at a swelling called the axon hillock, and travels for as far as 1 meter in humans or more in other species. It branches but usually maintains a constant diameter. At the farthest tip of the axon's branches are axon terminals, where the neuron can transmit a signal across the synapse to another cell. Neurons may lack dendrites or have no axon. The term neurite is used to describe either a dendrite or an axon, particularly when the cell is undifferentiated.
Most neurons receive signals via the dendrites and soma and send out signals down the axon. At the majority of synapses, signals cross from the axon of one neuron to a dendrite of another. However, synapses can connect an axon to another axon or a dendrite to another dendrite.
The signaling process is partly electrical and partly chemical. Neurons are electrically excitable, due to maintenance of voltage gradients across their membranes. If the voltage changes by a large enough amount over a short interval, the neuron generates an all-or-nothing electrochemical pulse called an action potential. This potential travels rapidly along the axon, and activates synaptic connections as it reaches them. Synaptic signals may be excitatory or inhibitory, increasing or reducing the net voltage that reaches the soma.
In most cases, neurons are generated by neural stem cells during brain development and childhood. Neurogenesis largely ceases during adulthood in most areas of the brain.

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  1. B

    Do neuron electrical signals generate an electromagnetic field or wave?

    I'm not sure where this belongs, I'm guessing biomedical, but I'm interested from a physics perspective. Do neurons generate an electromagnetic field? In other words, all the neural activity in the brain, does it generate electromagnetic fields? If so, what are the details of these fields? I...
  2. M

    A Solution to an ODE (Leaky Integrate and Fire Neuron Model)

    I'm looking for a general analytical solution to a particular ODE that comes up in neuroscience a lot. My feeling is that such a solution can't be obtained, otherwise someone would have presented it by now, but I don't have a good understanding of why it is so hard to solve. The equations as...
  3. M

    Fully analytical solution for the "Leaky Integrate and Fire" Neuron model

    Does anyone know if it is possible to develop a fully analytical solution for a leaky integrate and fire neuron driven by arbitrary time-varying current? Here's what I have so far (setting as many possible constants to 0 and 1): The equations: ## \dot{V} = - V + I(t) ## and if ##V(t) = 1##...
  4. TytoAlba95

    How does AP propagate in large myelinated neuron?

    I am reading https://www.ncbi.nlm.nih.gov/books/NBK21668/#_A6137_. It mentions that AP propagates along the length of the neuron due to the passive spread of depolarization, but it is only for small (thin, I presume?) myelinated neurons and large unmyelinated ones. My question is how do APs...
  5. kolleamm

    How does a neuron decide when to send a signal?

    In my quest to build better AI, I've been researching a lot on how the human brain works. I understand the overall structure of the neuron and how it communicates with other neurons. The only thing I don't understand is how a neuron decides when to send out a signal/response to other neurons...
  6. Psinter

    Neuron parts identification question

    From post: https://www.physicsforums.com/threads/random-thoughts-part-6.875108/page-180#post-5978198 I can see there is a gray-black stuff, but inside the gray-black stuff is a shiny lit moving stuff that moves in like a frenzy. What is the shiny lit moving stuff that moves across the...
  7. M

    Replacing a neuron by an artificial connection

    we know the fact that nerve cell can receives, processes, and transmits information through electrical and chemical signals and actually i am an 2nd years electric and automatic engineer so when it come to the field of biology i am not so good so if you try to make a special thread that can...
  8. somasimple

    Medical What is the Anatomy of a Dorsal Root Nerve Fascicle?

    Hi, Here is a little video I made about a dorsal root nerve fascicle. Original image from Professor Ennio Pannese https://www.amazon.com/dp/B00USZ5O4E/?tag=pfamazon01-20
  9. I

    Neuron lengths, sizes and quantity

    As I understand, there are peripheral neurons that stretch for up to a meter or more from the spine to wherever the muscle is. I was curious, does this apply to all the neurons that for example, move my right hand? Are all the neurons in my fingers individually that long, starting at the spine...
  10. A

    How realistic are modern neuron models?

    Nowadays we hear a lot about AI deep learning artificial neural networks. People speak about simulations of billions of neurons and even much more synapses. However, as far as I understand it, the artificial neurons used in these simulations are extremely simplified models of real biological...
  11. G

    Is there a limit to neuron multiplication in the hippocampus?

    Hi Friends! We know that nucleus of neurons remains like a closed blueprint!Is there any evolutionary pressure for cells not to multiply? Also in hippocampus they can multiply in only a highly limited number.Why different behaviour in hippocampus? Thanks in advance!
  12. M

    Medical Giant neuron around circumference of brain?

    http://www.sciencealert.com/a-giant-neuron-has-been-found-wrapped-around-the-entire-circumference-of-the-brain "For the first time, scientists have detected a giant neuron wrapped around the entire circumference of a mouse's brain, and it's so densely connected across both hemispheres, it could...
  13. I

    Question about the specific effects of SSRIs

    I know that SSRIs inhibit the reuptake of serotonin from synapses, and therefore cause the receptors on the postsynaptic neuron to be activated for a longer period of time. Does this have any effect on the signal sent? (for example, does it make it so the signal takes longer to process?, etc)
  14. I

    Name for the connection between a receptor and neuron?

    Hello, is there an official word that describes the connection (or "information exchange") between a receptor (or effector) and the neurons that they touch? I know that between neurons, there is a synaptic connection, and between muscles, that would be kinesthetic connection (I am guessing) but...
  15. F

    3d printing neuron with membrane potential

    Is it possible to 3d print a neuronal structure with a different material than neurons that would work just like a neuron with membrane potential?
  16. R

    Unraveling the Mystery of DNA in Neuron Cells & Vision

    Hi I want to know whether DNA inside our brain neuron cells helps us process images of what we see through our eyes.
  17. T

    Hodgin-Huxley model for a single neuron

    I am viewing (through https://www.edx.org/course ) an introduction course to computational neuroscience. In the second lecture, the Hodgin-Huxley model is considered. I am going over some of the questions and have encountered a problem with one of them (a picture of the exercise is attached...
  18. Z

    HR neuron model using analog computer technique

    Hi Everyone, I am simulating(using HSPICE) HR neuron model using analog computer technique but I am not getting the required response. I am using uA741 model of opamp and MLT04 model of multiplier. I have tested these components individually and they are working fine. I doubt there is something...
  19. davgonz90

    Understanding Neuron Polarization

    From what I understand, neurons at rest are in a state of polarization, with Na+ ions abundant on the outside of the cell and K+ ions abundant on the inside of the cell. During depolarization, sodium ions rush in, creating a highly positive charge on the inside of the cell relatively to the...
  20. G

    Whats Carrying the Current in Neurons?

    I was wondering what carries the current between two nodes of ranvier (under the myelin sheath) in a neuron. Books and sources say that the impulse jumps between nodes, but I have not found one that tells me how! Is it through the membrane, across microtubules, through the cytoplasm, or...
  21. K

    Artificial Intelligence neuron networks

    Homework Statement 1. Homework Statement For a neuron with the transfer function given below deterimne the weight updates after presentation of the two constructive training samples: xA = [2,-1] and xB = [-1,1], where the former one belongs to class A (desired output is 1), the latter to...
  22. Anand Wilson

    Telomere in Neuron Reprogramming

    what will be function of TERT,and shelterin complex protein in Neuron regeneration,is their any variant in telomere and telomerase between normal neuron and reprogramm neurons?
  23. U

    Biological neuron models and simulated data

    I have some very simple questions. 1. What are the real life applications of the biological neuron models (for example Hodgkin-Huxely model)? 2. Is their any online database from where I can get the original recordings data of a neuron? 3. or is there any way that I can...
  24. N

    Neuroscience: poisson and gauss in neuron firing rate model

    Hello! I was reading a journal article on modeling the interaction between different neural networks and I am confused about the follwoing method (cited below). It is describing the spike rate output of a neuron based on oscillating firing rates of excitatory (E) and inhibitory (I) inputs...
  25. M

    Neuron Electrical Model, time constant

    Hi all, I'm trying to understand the electrical model of a neuron, and I have 2 questions. I'm a little confused about the time constant in this electrical model of neuron recording: The time constant shown is tau = C*(Rm*Rs)/(Rm+Rs), which implies that the resistors are in parallel...
  26. sweet springs

    Ion acccount in neuron after firing

    Hi. I am learning how neuron transmit current. I am wondering after firing sodium ions are rich and potassium ions are poor in neuron cell. How ion concentrations come back to the original states before firing? Thanks for your help in advance.
  27. F

    Electromanetic radiation induce electrical current in neuron and create dream

    I am thinking if electromagnetic radiation can induce an electrical current in the neuron similar to the way antenna works. Since the antenna receive radio wave, which is a type of electromagnetic radiation to generate electricity. Can the neuron also receive electromagnetic radiation and induce...
  28. N

    Is the magnetic flux in a neuron star creation constant? Why?

    I did this problem on this British Physics Olympiad paper and it assumed that when a star bigger than the sun collapses under its own gravity to create a neuron star the magnetic flux stays constant. Please explain Thanks
  29. S

    Mechanism behind electrically induced neuron firings?

    Electricity affect neurons. For example, in 1791 Galvani made the legs of a dead frog twitch by exposing them to a spark, and more recently in history, electric currents through the brain has been used to deliberately induce "therapeutic" epileptic seizures. What I wonder about is the exact...
  30. Pythagorean

    Spiking neuron models (ion current models)

    Models like the Hodgkin-Huxley and Morris-Lecar include a current term: applied current. http://cropsci.illinois.edu/faculty/gca/bioengin/Top/Lit/GENESIS_book/iBoGpdf/chapt4.pdf From what I understand, experimentally, this is the injected current, applied by the experimenter. But what is it...
  31. G

    Medical Brain Synapse Density: Areas & Connections

    Does anyone know what areas of the brain have a denser amount of synapse? Are there more connections on the outside area than the inner areas, or is it uniform for the most part?
  32. M

    I am Writing a scifi story. Is my hypothetical neuron at least plausible?

    I'm writing a scifi story about a human undergoing rapid evolution due to his being repeatedly "connected" to an alien biological machine,that would be controlling the evolution through some kind of program. one of the changes would be a "master" cell that was able to regulate clusters of...
  33. M

    Membrane Potential question: neuron function or location?

    Homework Statement Which of the following is NOT important in determining a neurons membrane potential: The function of the neuron or the location of the neuron? Homework Equations N/a The Attempt at a Solution The function of a neuron is obviously the integration, summation, and...
  34. H

    Is the concentration outside and inside the neuron important?

    Homework Statement During the action potential, Na+ ions move into the cell at a rate of about 2.98×10-7mol/m2/s. How much power must be produced by the active transport system to produce this flow against a +25.2 mV potential difference? Assume that the axon is 11.7cm long and 19.6um in...
  35. fargoth

    Books and articles about neuron attributes.

    I'm looking for information on the different kinds of neurons and their possible interactions. I wish to program a model of sizable amount of neurons connected to each other in the various possible ways. so, can anyone direct me to a good reading material?
  36. N

    How heavy would you be on neuron star

    I have a problem that I can't figure out, as do most people I guess, so here goes. A neutron star is 1,000 times smaller than the Earth and has 450,000 times the mass of the earth. How many times heavier would you be on the surface of a neutron star?
  37. T

    Replace a neuron with a computer chip?

    Removing a brain cell and replacing with a chip must make one of two possible assumptions. The first is that what goes on inside a neuron is pertinent to consciousness. Alternatively, we might assume that what goes on inside a neuron is NOT pertinent to consciousness, that only the outward...
  38. Orion1

    Can Acoustical Velocities in Neutron Stellar Cores Exceed the Speed of Light?

    Neutron Stellar Cores... I watched a program in which a astrophysics professor suggested that in theoretical calculations, a Trans-Oppenheimer Neutron Stellar Core's acoustical velocity can exceed vacuum luminous velocity. v_s >= c Oppenheimer Neutron Stellar Density: p_n = \frac{3...
  39. zoobyshoe

    Exploring the Seizing Neuron: Cell Neurophysiology

    In my continuing research on seizures I came cross an article that goes into great technical depth. I'm wondering if anyone can read the following and expand and elucidate some of the biological terms. "The cellular neurophysiological correlate of an interictal epileptiform discharge in single...