Event-related slow potentials and activity of singly neurons in rat frontal cortex.

Event-related slow potentials and single unit activity were recorded from frontal cortex of unanesthetized, restrained rats trained to associate an auditory cue with rewarding medial forebrain bundle (MFB) stimulation. The majority of cortical units demonstrated an alteration of firing rate after the cue, with the predominant response being excitatory. The patterns of unit response during the interval between the cue and reinforcement varied considerable and few units showed a pattern which coincided temporally with the wave forms of the negative slow potential responses. These results indicate that negative cortical slow potential responses to meaningful stimuli are associated with an overall increase in activity of cortical neurons.