Direct cortical stimulation: a further study of treatment intensity effects on retrograde amnesia gradients

Rats were trained on a one-trial inhibitory avoidance task; at one of several intervals (0.1 sec-15 min) after training, they received electrical stimulation of either frontal or posterior cortex. The length of the RA gradient as measured on a 24-hr retention test varied with treatment intensity, particularly for frontal cortex stimulation. These results, together with previous findings, suggest that the minimal stimulation intensity necessary to produce RA increases with time after training. However, there also seems to be a maximal cortical stimulation intensity beyond which further increases in intensity do not extend the length of the RA gradient. In addition, the present results indicate that behavioral variables alter the lengths of RA gradients.