Blockade of GABAergic inhibition reveals reordered cortical somatotopic maps in rats that sustained neonatal forelimb removal

Journal of Neurophysiology
R D LaneRobert W Rhoades

Abstract

A previous study from this laboratory demonstrated that forelimb removal at birth results in invasion of the cuneate nucleus (CN) by sciatic nerve axons and the development of CN cells including thalamic projection neurons with receptive fields that include both the forelimb stump and the hindlimb. However, recordings from unit clusters in lamina IV of the primary somatosensory cortex (SI) of these animals revealed the presence of only a very few sites in the forelimb stump representation where responses to hindlimb stimulation could also be recorded. In the present study we tested the possibility that input from the hindlimb was suppressed in lamina IV of the cortical stump representation via GABAergic inhibitory mechanisms by mapping this cortical region, applying the gamma-aminobutyric acid-A (GABA(A)) and GABA(B) receptor antagonists bicuculline and phaclofen (50 microM each), and then remapping the same sites. In six neonatally manipulated rats, 15 of 242 sites (6.2%) in the stump representation responded to hindlimb stimulation before GABA receptor blockade and 107 (44.2%) of the same sites responded to stimulation of the hindlimb during blockade (P < 0.05). In six normal adult rats, 7 of 264 sites (2.7%) in the forelimb ...Continue Reading

References

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Citations

Sep 11, 2003·The Journal of Comparative Neurology·Theodore H BowlusRobert W Rhoades
May 11, 2000·Journal of Neurophysiology·S L FlorenceF Strata
May 22, 2001·The European Journal of Neuroscience·S L FlorenceM M Niblock
Nov 17, 2012·Journal of Neurophysiology·Jason V ThompsonTimothy Q Gentner

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