J Neurophysiol 102: 437-450, 2009.
First published April 29, 2009; doi:10.1152/jn.00277.2009
0022-3077/09 $8.00
Influence of Subcortical Inhibition on Barrel Cortex Receptive Fields
Akio Hirata,
Juan Aguilar and
Manuel A. Castro-Alamancos
Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
Submitted 30 March 2009;
accepted in final form 21 April 2009
Influence of subcortical inhibition on barrel cortex receptive fields. By the time neural responses driven by vibrissa stimuli reach the barrel cortex, they have undergone significant spatial and temporal transformations within subcortical relays. A major regulator of these transformations is thought to be subcortical GABA-mediated inhibition, but the actual degree of this influence is unknown. We used disinhibition produced by GABA receptor antagonists to unmask the excitatory sensory responses that are normally suppressed by inhibition in the main subcortical sensory relays to barrel cortex; principal trigeminal (Pr5) and primary thalamic (VPM) nuclei. We found that, within subcortical relays, inhibition only slightly suppresses short-latency receptive field responses, but robustly suppresses long-latency center and surround receptive field responses. However, the long-latency subcortical effects of inhibition are mostly not reflected in the barrel cortex. The most robust effect of subcortical inhibition on barrel cortex responses is to transiently suppress the receptive field responses of high-frequency sensory stimuli. This transient adaptation caused by subcortical inhibition recovers within a few stimuli and gives way to a steady-state adaptation that is independent of subcortical inhibition.
Address for reprint requests and other correspondence: M. Castro-Alamancos, Depart. of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Ln., Philadelphia, PA 19129 (E-mail: mcastro{at}drexelmed.edu)
Copyright © 2009 by the The American Physiological Society.
