Fig. 4.

Response rate (number of lever presses per minute) of male (upper) and female (lower) rat offspring born to dams exposed to either TCDD or PCB126 at three different doses in phases 1, 2 and 3 in the DRL component. Doses of TCDD were 50, 200 and 800 ng/kg, respectively, and those of PCB126 were 500, 2,000 and 8,000 ng/kg, respectively. Open, black and gray bars indicate control, TCDD and PCB126 groups, respectively. Bars indicate the mean and SEM of the number of lever presses in each ten-session phase