FIGURE 3.

Time course of dose-dependent effects of kratom on PFC spectral power. (A,B) Representative power spectra showing dose-dependent (0, 0.5, 1.0 mg/kg) effects of kratom 30 min post-injection on day 1 and day 7. (C) High dose kratom increased delta power on day 1 and day 7 whereas low dose kratom increased delta power on day 7. (D) Reduced theta power in response to only high dose kratom on day 1. On day 7, decreased theta power was shown in response to both doses of kratom. (E,F) No drug-induced changes were observed in beta or low gamma power on day 1 or day 7. (G) On day 1, kratom had no effects on high gamma power. Reduced high gamma power was, however, evident on day 7 in response to high dose kratom. N = 7–10 rats per group, with 2 electrodes/rat. Curves are represented as means with jackknife estimates of sem depicted by the shaded areas. Bars represent mean ± sem. *p < 0.05, **p < 0.01 compared to saline control rats. ^## p < 0.01 compared to low dose kratom treated rats.