VISUALLY-TRIGGERED OSCILLATIONS IN THE CAT LATERAL POSTERIOR-PULVINARCOMPLEX

THE so-called 40 Hz oscillations are found at almost all stages of vis ual processing are thought to play a critical role in perception. The goal of this investigation was to look at the presence of stimulus-spe cific oscillations in the lateral posterior-pulvinar complex of the th alampus (LP-P) for which the oscillations were still not described. Rh ythmic patterns in multiunit LP-P activity of anaesthetized cats were revealed in 14% of recording sites. With the exception of one pool of LP-P cells that exhibited stimulus-dependent rhythmic activity similar to 130 Hz, 90% of autocorrelograms were modulated between 18 and 74 H z with dominant frequencies of 20-33 Hz Since the LP-P sends efferents to the visual cortex it seems possible that oscillations from the LP- P can propagate to cortical neurones, especially to complex cells, for which similar dominant frequencies were noted by previous investigato rs.