Fig. 3.
Cocaine induces STN theta and beta oscillations decrease when compared to baseline in ShA, but not LgA sessions, while STN gamma oscillations appear as a marker of cocaine intake. a Graph showing the variations in STN oscillation powers induced by cocaine consumption, compared to baseline recordings, during the first 30 min of ShA (days 1–5, black line) and LgA sessions (days 1–5, green line; days 6–10, red line; days 11–15 purple line). When expressed as percentage of the baseline, cocaine induced a decreases in LFPs power spectrum for the low (theta and beta bands) frequencies during ShA that disappeared during LgA sessions, where high-frequency oscillations increased in the gamma band. b–d Bar graphs showing the averaged STN oscillation powers during baseline (open bars) and cocaine recordings (filled bars) for ShA (days 1–5, black bars) and LgA sessions (days 1–5, green bars; days 6–10, red bars; days 11–15 purple bars) in theta (b), beta (c), and gamma (d) bands. (ShA 1–5: b t5 = 5.138, P < 0.01; c t5 = 7.213, P < 0.001; d t5 = 0.396, n.s.; LgA 1–5: b t5 = 0.9415, n.s.; c t5 = 1.416, n.s.; d t5 = 2.873, P < 0.05; LgA 6–10: b t5 = 0.5672, n.s.; c t5 = 0.9004, n.s.; d t5 = 3.607, P < 0.05; LgA 11–15: b t5 = 2.256, P = 0.0738, n.s.; c t5 = 0.9542, P = 0.3838, n.s.; d t5 = 3.847, P = 0.012, paired t-test). Dotted lines in the LgA bars indicate the level reached during ShA sessions. e Diagrams showing the correlations (bold lines) between STN oscillation power of the gamma band and the amount of cocaine taken during the first 30 min of ShA (left panel) and LgA sessions (right panel) for each animal (light shaded-color circles). A significant correlation was found during ShA (F1,48 = 18.39, P < 0.001; ANCOVA controlled for inter-individual differences) that disappeared during the LgA session (F1,46 = 1.96, n.s.). All data are means with SEM, *P < 0.05, **P < 0.01, ***P < 0.001 vs. baseline, paired t-test