While the rat was performing a go/no-go alternation task with a 10-s delay period, neuronal activity was recorded from electrodes chronically implanted in the prefrontal cortex (PFC) and the dorsomedial thalamus (DMT). In both PFC and DMT, neuronal activity during the delay period prior to a 'go' response was different from that prior to a 'no-go' response. The results suggest that during the delay period the PFC and DMT maintain a memory for the generation of the response. Furthermore, it was found that DMT neuronal activity in the delay period was different between correct and error trials. Therefore, the DMT may be primarily important in performing the alternation behavior.