Pulvinar participates in synchronizing neural assemblies in the visual cortex, in cats

Abstract

It has been proposed that the perception of a coherent image necessitates two processes, that is, an ensemble of neurons which synchronizes discharges of individual cells and stimulus-specific gamma-band (γ) neuronal oscillations which may serve as carrier signals for a temporal code. We tested the hypothesis that cortical γ-oscillations and synchronization depend upon the interactions between the lateral posterior-pulvinar complex of the thalamus (LP-P) and visual cortex. Local reversible inactivation of the LP-P was achieved by pressure injections of γ-aminobutyric acid (GABA). In the majority of cases the LP-P depression decreased the strength of the synchronization and oscillations. Also, the results demonstrate that the occurrence of stimulus-dependent oscillations and the synchronization of neuronal responses are two distinct processes and consequently they may occur or disappear independently of each other.