Effects of lesions of prefrontal cortex and dorsomedial thalamus on delayed go/no-go alternation in rats.

The effect of prefrontal cortex (PFC) and/or dorsomedial thalamus (DMT) lesions on a delayed go/no-go alternation task was studied in the rat. The lesion gave rise to the impairment of smooth alternation of one response to another, resulting in the generation of some successive repetitions of either response. However, either type of response was generated in virtually equal frequencies during pre- and post-surgery sessions. These results suggest that the DMT and PFC are involved in the memory and response control process for generating the alternation response, and they do not mediate either one type of response. Furthermore, DMT or DMT/PFC lesions induced a larger behavioral impairment than PFC lesions indicating that the DMT plays a major role in generating the alternation behavior based on the memory for the previous response.