Fig. 3.

Behavioral stupor in response to escalating doses of heroin, recorded across daily (40-min) observation sessions. Stupor was recorded in response to escalating doses of heroin administered during chronic exposure (Heroin/Heroin, black circles; Saline/Heroin, white circles) and, following an extended withdrawal period, during chronic re-exposure (Heroin/Heroin, grey circles). The daily mean, averaged across the entire observation session, is shown to the right of each expanded dataset. * P<0.05, between-group comparisons; # P<0.05, within-group comparisons; ^a P<0.05, within-group comparison to exposure data on the previous day. Data are presented as mean ± S.E.M.