Biology:Shunting inhibition
Shunting inhibition, also known as divisive inhibition, is a form of postsynaptic potential inhibition that can be represented mathematically as reducing the excitatory potential by division, rather than linear subtraction.[1] The term "shunting" is used because of the synaptic conductance short-circuit currents that are generated at adjacent excitatory synapses. If a shunting inhibitory synapse is activated, the input resistance is reduced locally. The amplitude of subsequent excitatory postsynaptic potential (EPSP) is reduced by this, in accordance with Ohm's Law.[2] This simple scenario arises if the inhibitory synaptic reversal potential is identical to or even more negative than the resting potential.[3]
Discovery
Shunting inhibition was discovered by Fatt and Katz in 1953.[2][4]
Mechanism
Shunting inhibition is theorized to be a type of gain control mechanism, regulating the responses of neurons.[5][6] Simple inhibition such as hyperpolarization has a subtractive effect on the depolarization caused by concurrent excitation, whereas shunting inhibition can in some cases account for a divisive effect.[7]
Some evidence exists that shunting inhibition can have a divisive effect on neuronal responses, at least on subthreshold postsynaptic potentials.[8] In a 2005 article, researchers Abbott and Chance state that "Although the importance of gain modulation and multiplicative interaction in general has been appreciated for many years, it has proven difficult to uncover a realistic biophysical mechanism by which it can occur. It is important to note that, despite comments in the literature to the contrary (see above), divisive inhibition of neuronal responses cannot arise from shunting inhibition. This has been shown theoretically as well as experimentally – inhibition has the same subtractive effect on firing rates whether it is of the shunting or hyperpolarizing variety."[7] Thus, shunting inhibition does not provide a plausible mechanism for neuronal gain modulation.[7]
See also
References
- ↑ "Coding & Vision Lesson 4: Cell Types". Allen Institute. https://www.youtube.com/watch?v=rWBW-OrVGAA&list=PLCEC78997E3E2DAB4&index=9.
- ↑ 2.0 2.1 "Chapter 5 - Thermodynamics and Kinetics of Chloride Transport in Neurons: An Outline" (in en). Physiology and Pathology of Chloride Transporters and Channels in the Nervous System. San Diego: Academic Press. 2010-01-01. pp. 81–108. doi:10.1016/b978-0-12-374373-2.00005-4.
- ↑ "How inhibition shapes cortical activity" (in English). Neuron 72 (2): 231–243. October 2011. doi:10.1016/j.neuron.2011.09.027. PMID 22017986.
- ↑ "The effect of inhibitory nerve impulses on a crustacean muscle fibre". The Journal of Physiology 121 (2): 374–389. August 1953. doi:10.1113/jphysiol.1953.sp004952. PMID 13085341.
- ↑ The Physiology of Synapses. Berlin: Springer-Verlag. 1964.
- ↑ "Arithmetical operations performed by nerve cells". Brain Research 69 (1): 115–124. March 1974. doi:10.1016/0006-8993(74)90375-8. PMID 4817903.
- ↑ 7.0 7.1 7.2 "Drivers and modulators from push-pull and balanced synaptic input". Drivers and modulators from push-pull balanced synaptic input. Progress in Brain Research. 149. 2005. pp. 147–155. doi:10.1016/S0079-6123(05)49011-1. ISBN 9780444516794. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7CV6-4H9R14B-H&_u%0Aser=791130&_coverDate=12/31/2005&_rdoc=1&_fmt=high&_orig=search&_sort=d&_do%0Acanchor=&view=c&_acct=C000043379&_version=1&_urlVersion=0&_userid=791130&md%0A5=922f74a2bfe63492639d6da5996d566c.
- ↑ "Shunting inhibition does not have a divisive effect on firing rates". Neural Computation 9 (5): 1001–1013. July 1997. doi:10.1162/neco.1997.9.5.1001. PMID 9188191.
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