Long-term retention of classical eyeblink conditioning in amnesia.

The retention of classical eyeblink conditioning was investigated in amnesic patients 10 days and 2 months after original learning. During reacquisition, the first CR occurred earlier and the CR frequencies during the first 10 trials were higher than in the baseline session. The overall CR rates increased significantly across sessions during both acquisition and extinction. The amnesics did not differ from matched controls on any of these effects, although they did not recall previous conditioning sessions and did not become fully aware of CS-US contingencies. The smaller number of electrodermal responses to the CS tone during extinction in the amnesics may relate to their lack of insight into the change in the reinforcement schedule.