POSTOPERATIVE CHANGES OF RAT EEG VARIANCE

Concerning an EEG parameter variance, the long-term postoperative chan ges were observed in rats chronically implanted with bipolar depth ele ctrodes for EEG recordings. The cortico-hippocampal EEG signals were c ontinuously digitized and their variances were computed for each 1 min in real time. Daily mean of the EEG variance gradually increased over 2 weeks after surgery for the implantation of chronic electrodes and, then, reached a plateau. To observe the absolute quantity of the dept h EEG in the rat, at least 2 weeks are required before data collection s.