A retrograde gradient for disruption of a conditioned aversion to drinking cold water by ECS administered during the CS-US interval

Rats were used to examine the effects, upon a conditioned aversion to cold drinking water, of electroconvulsive shock (ECS) delivered during the delay between cue and unconditioned stimulus. An injection of LiCl (US) 30 min after ingestion of novel cold water (CS) produced a reliable aversion to the cold water. ECS given immediately following the ingestion of cold water substantially attenuated this aversion. An orderly decrease in the attenuation of the aversion was observed when ECS was delayed 5, 10 or 20 min after offset of the cold water cue. The results indicate that ingestive cue aversions can be formed without electrochemical neural-transmission-based representation of the cue being maintained during the CS-US interval. The differential effectiveness of ECS suggests that this agent retroactively interferes with processing of the ingestive cue.