Excitatory-inhibitory processes in parietal association neurons during reticular activation and sleep-waking cycle.

Excitatory-inhibitory processes of parietal association neurons were studied during reticular-induced EEG activation and natural sleep-waking cycle. The probability of antidromic invasion in long-axon cells is enhanced following midbrain reticular stimulation and during both waking (W) and desynchronized sleep (D) states compared to slow-wave sleep. The thalamically elicited inhibitory phase occurs with a shorter latency following reticular stimulation and during W and D states; this is due to the reduced duration, during all these experimental conditions, of secondary excitatory processes. The duration of the inhibitory period is shorter during reticular activation; the postinhibitory rebound occurs at shorter latencies and is sharper following reticular stimulation and during W and D states. The similarity between reticular effects and changes during both W and D states is discussed.