A technique for recording and integrating multiple unit activity simultaneously with the EEG in chronic animals.

Abstract Multiple unit activity, with concurrent EEG recordings, has been recorded and integrated from various brain sites in chronic, unrestrained animals. The output of the integration circuit follows rapid changes in both frequency and amplitude of multiple unit activity without being disproportionately influenced by isolated, large amplitude spikes. Thus, action potentials from a large population of units can be quantitated and the resultant activity patterns compared with concurrent slow wave EEG activity recorded from the same site.