[DSP 4, a neurotoxic agent that destroys noradrenergic endings, selectively increases "expectancy" in the cat]

Cats were treated with DSP 4, a neurotoxic agent known to destroy central noradrenergic endings. A significant increase was subsequently noticed in the amount of time spent by the treated animals in an attitude of "expectancy", i.e. of motionless waiting for an "event to occur". They even developed this attitude when no such real situation existed. Concomitantly, an increase was noticed in the power of the 14 Hz electrocortical rhythms recorded over the somatic sensory cortex. These patterns, designated as "mu" rhythms, had previously been shown to characterize this particular type of attentive state. The present data tends to confirm our previous hypothesis, that immobile expectancy and its accompanying electrocortical pattern are under a noradrenergic inhibitory control.