Figure 6.

Slow oscillation (SO) of VTA DA neuron is time-dependently changed in response to morphine challenge after a single morphine exposure. Rats received morphine (20 mg/kg, s.c.) or saline, and then challenged with morphine (5 mg/kg, i.v.) 24, 72 or 120 hours later. A: representative spectral chart. B: group summary. *P < 0.05, Paired t test, compared to respective control.