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Lateral Inhibition[edit]

In neurobiology, lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors. Lateral inhibition disables the spreading of action potentials from excited neurons to neighboring neurons in the lateral direction. This creates a contrast in stimulation that allows increased sensory perception. It is also referred to as lateral antagonism and occurs primarily in visual processes, but also in tactile, auditory, and even olfactory processing.[1] Cells that utilize lateral inhibition appear primarily in the cerebral cortex and thalamus and make up lateral inhibitory networks (LINs).[2] Artificial lateral inhibition has been incorporated into artificial sensory systems, such as vision chips,[3] hearing systems,[4] and optical mice.[5][6] An often under-appreciated point is that although lateral inhibition is visualised in a spatial sense, it is also thought to exist in what is known as "lateral inhibition across abstract dimensions." This refers to lateral inhibition between neurons that are not adjacent in a spatial sense, but in terms of modality of stimulus. This phenomenon is thought to aid in colour discrimination.[7]

Tactile Lateral Inhibition[edit]

Sensory information collected by the peripheral nervous system is transmitted to specific areas of the primary somatosensory area in the parietal cortex according to its origin on any given part of the body. For each neuron in the primary somatosensory area, there is a corresponding region of the skin that is stimulated or inhibited by that neuron.[8] The regions that correspond to a location on the somatosensory cortex are mapped by a homonculus. This corresponding region of the skin is referred to as the neuron’s receptive field. The most sensitive regions of our body have the greatest representation in any given cortical area, but they also have the smallest receptive fields. The lips, tongue, and fingers are examples of this phenomena.[9] Each receptive field is composed of two regions: a central excitatory region and a peripheral inhibitory region. One entire receptive field can overlap with other receptive fields, making it difficult to differentiate between stimulation locations, but lateral inhibition helps to reduce that overlap.[10] When an area of the skin is touched, the central excitatory region activates and the peripheral region is inhibited, creating a contrast in sensation and allowing sensory precision. The person can then pinpoint exactly which part of the skin is being touched. In the face of inhibition, only the neurons that are most stimulated and least inhibited will fire, so the firing pattern tends to concentrate at stimulus peaks. This ability becomes less precise as stimulation moves from areas with small receptive fields to larger receptive fields, i.e. moving from the fingertips to the forearm to the upper arm.[11]

Auditory Lateral Inhibition[edit]

Similarities between sensory processes of the skin and the auditory system suggest lateral inhibition could play a role in auditory processing. The basilar membrane in the cochlea has receptive fields similar to the receptive fields of the skin and eyes. Also, neighboring cells in the auditory cortex have similar specific frequencies that cause them to fire, creating a map of sound frequencies similar to that of the somatosensory cortex.[12] Lateral inhibition in tonotopic channels can be found in the inferior colliculus and at higher levels of auditory processing in the brain. However, the role that lateral inhibition plays in auditory sensation is unclear. Some scientist found that lateral inhibition could play a role in sharpening spatial input patterns and temporal changes in sensation,[13] others propose it plays an important role in processing low or high tones.

Lateral inhibition is also thought to play a role in suppressing tinnitus. Tinnitus can occur when damage to the cochlea creates a greater reduction of inhibition than excitation, allowing neurons to become aware of sound without sound actually reaching the ear.[14] This causes a person to report hearing a slight rining, or other simple sound, even though sound is not being produced. If certain sound frequencies that contribute to inhibition more than excitation are produced, tinnitus can be suppressed.[15] Evidence supports findings that high-frequency sounds are best for inhibition and therefore best for reducing some types of tinnitus. This research is still in the early stages of development and has yet to establish any concrete connections or solutions, but hopefully will in the near future.

In mustached bats, evidence supports the hypothesis that lateral inhibitory processes of the auditory system contribute to improved auditory information processing. Lateral inhibition would occur in the medial and dorsal divisions of the medial geniculate nucleus of mustached bats, along with positive feedback.[16] The exact functions of these regions are unclear, but they do contribute to selective auditory processing responses. These processes could play a role in auditory functioning of other mammals, such as cats.

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Extras[edit]

Extensions of lateral inhibition are edge enhancement, simultaneous contrast, and mutual inhibition.

Bullets[edit]

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Points[edit]

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    1. number 1 point 1

Links[edit]

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Middlebury College on Wikipedia

References[edit]

  1. ^ Yantis, Steven (2014). Sensation and Perception. New York, NY: Worth Publishers. p. 77.
  2. ^ Shamma, Shihab A. (03). "Speech processing in the auditory system II: Lateral inhibition and the central processing of speech evoked activity in the auditory nerve". The Journal of the Acoustical Society of America. 78 (5): 1623. doi:10.1121/1.392800. PMID 3840813. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Unknown parameter |month= ignored (help)
  3. ^ Alireza Moini (2000). Vision Chips. Springer. ISBN 0-7923-8664-7.
  4. ^ Christoph von der Malsburg et al. (editors) (1996). Artificial Neural Networks: ICANN 96. Springer. ISBN 3-540-61510-5. {{cite book}}: |author= has generic name (help)
  5. ^ Alireza Moini (1997). "Vision Chips" (PDF).
  6. ^ Richard F. Lyon (1981), "The Optical Mouse and an Architectural Methodology for Smart Digital Sensors" (PDF), Xerox PARC report VLSI-81-1
  7. ^ RHS Carpenter (1997). Neurophysiology. Arnold, London.
  8. ^ Heller, Morton A. (2013). Psychlogy of Touch and Blindness. New York, NY: Taylor and Francis. p. 20.
  9. ^ Heller, Morton A. (2013). Psychlogy of Touch and Blindness. New York, NY: Taylor and Francis. p. 20.
  10. ^ Fox, Kevin (2008). Barrel Cortex. New York: Cambridge University Press. p. 127.
  11. ^ Heller, Morton A. (2013). Psychlogy of Touch and Blindness. New York, NY: Taylor and Francis. p. 20.
  12. ^ Bernstein, Douglas A. (2008). Psychology. Boston, MA: Houghton Mifflin Company. p. 118.
  13. ^ Shamma, Shihab A. (03). "Speech processing in the auditory system II: Lateral inhibition and the central processing of speech evoked activity in the auditory nerve". The Journal of the Acoustical Society of America. 78 (5): 1622–1632. doi:10.1121/1.392800. PMID 3840813. {{cite journal}}: Check date values in: |date= and |year= / |date= mismatch (help); Unknown parameter |month= ignored (help)
  14. ^ Moller, Aage R. (2011). Textbook of Tinnitus. New York, NY: Springer. p. 96.
  15. ^ Moller, Aage R. (2011). Textbook of Tinnitus. New York, NY: Springer. p. 96.
  16. ^ Gallagher, Michela (2003). "Biological Psychology". Handbook of Psychology. 3: 84. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
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