- Barrel cortex
The barrel cortex refers to the dark-staining regions of layer four of the
somatosensory cortex ofrodents where somatosensory inputs from the contralateral side of the body come in from thethalamus . The rest of this article will focus on the 'whisker barrels' in somatosensory cortex. Inputs from the thalamus carrying information from a given whisker terminate in discrete areas of layer IV forming anatomically distinguishable areas (barrels) which are separated from each other by areas called septa. These structures were first discovered by Woolsey and Van der Loos (1970). Recognizing that the array was similar to that of the vibrissae on the mystacial pad, they hypothesized that the barrels were the "cortical correlates of the mystacial vibrissae" and that "one barrel represents onevibrissa ".Due to its clear anatomical structure and functional significance, the barrel cortex has played an important role in neuroscience. The majority of what is known about corticothalamic processing comes from studying the barrel cortex and researchers have intensively studied the barrel cortex as a model of
neocortical column .Neurons within the layer IV barrel cortex directly code for whisker displacement. That is to say, that the neuron within a given barrel will fire when the whisker that barrel represents is moved. These neurons also show directional sensitivity, certain neurons will only fire when the whisker is moved in a specific direction [1, 2] .
Neurons in the barrel cortex exhibit the property of
synaptic plasticity that allows them to alter the vibrissae to which they respond depending on the rodent's history of tactile experience [3] . The field of barrel cortex research has matured to the stage where a book has been published on the subject [4] .References
[1] Swadlow HA. Efferent neurons and suspected interneurons in S-1 vibrissa cortex of the awake rabbit: receptive fields and axonal properties. J Neurophysiol 62: 288–308, 1989
[2] Swadlow HA. Efferent neurons and suspected interneurons in second somatosensory cortex of the awake rabbit: receptive fields and axonal properties. J Neurophysiol 66: 1392–1409, 1991
[3] Hardingham N, Glazewski S, Pakhotin P, Mizuno K, Chapman PF, Giese KP, Fox K. Neocortical long-term potentiation and experience-dependent synaptic plasticity require alpha-calcium/calmodulin-dependent protein kinase II auto-phosphorylation. J Neurosci. 2003 Jun 1;23(11):4428-36.
[4] Fox, K. Barrel Cortex. Cambridge, New York, Melbourne. Cambridge University Press. 2008. ISBN 978-0-521-85217-3
External links
*Research groups working on barrel cortex:
* [http://www.barrels.uni-freiburg.de Barrel Group, Freiburg]
* [http://www.cardiff.ac.uk/biosi/contactsandpeople/stafflist/e-h/fox-kevin-prof.html Barrel cortex group, Cardiff]
* [http://cnr.iop.kcl.ac.uk/default.aspx?pageid=169 Finnerty lab, MRC Centre for Neurodegeneration Research, London] Books on barrel cortex [http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521852173 Barrel Cortex book]
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