Visually-triggered oscillations in the cat lateral posterior-pulvinar complex.

The so-called 40 Hz oscillations are found at almost all stages of visual processing are thought to play a critical role in perception. The goal of this investigation was to look at the presence of stimulus-specific oscillations in the lateral posterior-pulvinar complex of the thalampus (LP-P) for which the oscillations were still not described. Rhythmic 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 approximately 130 Hz, 90% of autocorrelograms were modulated between 18 and 74 Hz 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 investigators.