FIGURE 4.

Prior history of extended exposure to ketamine does not alter resting oscillatory activity. The effect of the previous history of ketamine exposure on baseline oscillatory activity was investigated by comparing the oscillatory power during the –32 to –2 min interval preceding the first injection on each recording session. Sessions were separated by at least 1 week. The x axis of each plot indicates the number of previous ketamine exposure sessions (0 indicates days that the rat had no prior ketamine exposure session). A significant difference between the number of ketamine sessions received and oscillatory power (y axis) would suggest that prior ketamine exposures produces persistent changes in oscillatory activity that last at least 1 week, which was the time between ketamine sessions. Individual plots are organized by region (row) and frequency band (column). A within-subject analysis (within subject = number of ketamine sessions, between subject = animal) identified no significant relationships between the number of previous ketamine exposure sessions and oscillatory power at any frequency band (paired t-test, p > 0.05, n = 7).