Medial agranular cortex activity related to event-related potential generation in the rat

Neuronal firings and local field potentials were recorded in the medial agranular cortex (Fr2) together with surface event-related potentials (ERPs) during an auditory oddball task in the rat. 10/32 Fr2 neurons showed a sustained increase in firing frequency in response to target tone (100-615 ms from the tone onset) with an activation peak corresponding to surface P100 component. At the intra-cortical recording site, local P100 component was observed with greater peak amplitude than that on the surface. No conspicuous neuronal response was evoked by non-target tone. The results suggest that the rat Fr2 is involved in stimulus discrimination and generation of ERPs during the oddball task.