Memory Trace Disruption by Cortical Spreading Depression

Abstract

Eight rats were trained under unilateral spreading depression to make a brightness discrimination in a T-maze for water reward. Following training, all Ss were given a single trial (transfer trial) with neither hemisphere depressed. Four Ss were replaced in their home cages for 24 hr. and then the untrained hemisphere was tested by depressing the trained hemisphere. These Ss showed significant transfer of the learning. The other 4 Ss were depressed on the untrained side 1 hr. after the transfer trial. Transfer to the untrained side was then tested 6 hr. after this depression. No transfer appeared in this group, apparently because the depression of the untrained side after the transfer trial disrupted the transferred engram.