GABA(B) receptor-mediated presynaptic inhibition reverses inter-columnar covariability of synaptic actions by intracortical axons in the rat barrel cortex
08.11.2012
Sato H, Toyoda H, Saito M, Kobayashi M, Althof D, Kulik A, Kang Y.
Eur J Neurosci. 2013 Jan;37(2):190-202
Intracortical axons originating from pyramidal cells in layer 3 of the somatosensory cortex are shared between adjacent columns and receive the presynaptic inhibition that is mediated by GABA(B) receptor. Synaptic actions by intracortical axons of layer 3 cells would covary between the two adjacent columns in reponse to stimulation of layer 3 of the either column. GABA(B) receptor-mediated presynaptic inhibition was examined whether it affects the covariability of synaptic actions by intracortical axons between adjacent columns in rat barrel cortex. Paired stimulations of layer 3 evoked the 1st and 2nd EPSCs of varying amplitudes, yielding varying paired-pulse depression of EPSCs in pyramidal cells in the stimulated column, but not in its adjacent column. The amplitude of the 2nd EPSCs was inversely proportional to that of the 1st EPSC in layer 3 pyramidal cells in the stimulated column, yielding a negative correlation coefficient between the 1st and 2nd EPSCs. Agonist and antagonist attenuated paired-pulse depression. Simultaneous recordings from two layer 3 cells in stimulated and adjacent columns: positive correlation between the paired 1st EPSC amplitudes and a negative correlation between the paired 2nd EPSC amplitudes.
