Disruption of conditioned taste aversion: the effect of ECS after the taste-illness interval

Rats were taught a conditioned taste aversion (CTA) by pairing a 10% sucrose solution (CS) with lithium chloride-induced poisoning (UCS) 30 min later. The extent to which electroconvulsive shock (ECS) (80 mA for 600 msec) impaired the acquisition of the CTA was studied by either interpolating the ECS within the CS-UCS interval or by administering it at various times following the UCS (0, 5, 10, 15, 30, 60 and 120 min). There was a pronounced although limited loss of learning among all groups when ECS was delivered no later than 10 min after the UCS. When ECS was administered between 15 and 120 min, the overall aversion acquired did not differ significantly from that of the poisoned controls. It is concluded that while the stability of CTA seems to increase at about the same time the behavioral concomitants of lithium toxicity become apparent (10 min), this phenomenon does not necessarily imply that the neural trace underlying CTA has consolidated into a less labile state.