The effects of changing state on elicited ponto-geniculo-occipital (PGO) waves

Abstract

Waves similar to ponto-geniculo-occipital (PGO) waves occurring spontaneously in the lateral geniculate body (LGB) pons, and occipital cortex during rapid eye movement (REM) sleep can be elicited in the LGB and the cortex by tones in waking (W), non-rapid eye movement sleep (NREM), and REM. In W, the elicited waves (PGO E) sometimes accompany orienting responses (OR). We have hypothesized that REM is a state resembling exaggerated “orienting” in part because spontaneous PGO waves similar to PGO E accompanying OR are constantly observed in REM. The present experiment tested whether: (1) PGO E and OR were strongly correlated in W across a large number of tone presentations as might be predicted if PGO E were central wave from markers for a state of orienting; and (2) recovery of responsiveness of PGO E to tones would then be greater in REM than NREM, as might be expected if REM but not NREM were a state in which central mechanisms of orienting were highly active. Tones were presented in W and tn REM and NREM to six cats in order to measure the degree of habituation of OR and PGO E simultaneously. PGO E and OR exhibited a degree of independence: the former were readily produced in W despite the rapid decline in OR across trials. Recovery in the amplitude of PGO E occurred in both NREM and REM. The recovery tended to be greater in REM and NREM, although this was not statistically significant. Refinements of the theory that REM represents a state of exaggerated internal orienting are discussed.