Extended retrograde amnesia gradients: peripheral epinephrine and frontal cortex stimulation.

This experiment examined the possibility that hormonal responses to training may increase the susceptibility of memory to an amnestic agent. As long as one week after training, rats that received a subcutaneous epinephrine injection shortly before electrical stimulation of frontal cortex exhibited amnesia on later retention tests. These findings suggest that retrograde amnesia gradients may reflect, in part, maximum susceptibility to amnesia shortly after training because the effects on memory of an amnestic agent are potentiated by the neuroendocrine response to training.