DISSOCIATED PARADOXICAL SLEEP-DEPRIVATION EFFECTS ON INHIBITORY AVOIDANCE AND CONDITIONED FEAR

Rats were submitted to paradoxical sleep deprivation (PSD) for 24, 72, or 96 h and were trained on a double aversively motivated task, encom passing a step-through inhibitory avoidance and a classical conditioni ng of fear to a brief tone serving as conditional stimulus. Retention test of the inhibitory avoidance was performed at the same apparatus o f training (without tone presentation). Retention of conditioned fear was assessed in an open field apparatus, where the freezing reaction t o the tone was measured. PSD for 24 and 72 h preceding the training se ssion had no effect on either task. However, PSD during the 96 h prece ding the training session impaired acquisition of inhibitory avoidance , but had no effect on classically conditioned fear. It is concluded t hat PSD had differential effects on the two tasks, both aversively mot ivated and trained at the same time and conditions.