Time-dependent recovery from electroconvulsive shock-induced amnesia☆

To examine time-dependent recovery from ECS-induced amnesia, 44 hooded rats were trained to leverpress for food. On treatment day the first leverpress was followed by footshock and ECS or sham ECS (SECS). Animals in both treatment conditions then experienced a 10-min extinction session either 1 or 3 days following treatment. For both the 1-day and 3-day delay ECS groups, the latencies to the first response during extinction were lower than the latencies of the corresponding SECS groups. When extinction followed treatment by 1 day, the ECS rats also made more responses during the test than the SECS rats; however, when tested 3 days after treatment, the ECS and SECS groups did not differ on extinction response rate. In this operant setting, therefore, time-dependent recovery from amnesia can be demonstrated with response rate as the amnesia measure. In addition, since both groups of SECS animals exhibited significant interrelationships of measures following treatment and the same measures were not associated in the ECS groups, it was hypothesized that the proactive effects of ECS include a reduction in the stability of performance.