Fig. 3

a The X-axis represents the number of days of sucrose self-administration training. The Y-axis represents the number of responses, with ● representing active nose-pokes and ○ representing inactive nose-poke. There was a significant increase in the number of active but not inactive nose-poke responses over this training period, rats acquired a stable sucrose self-administration response after 7 total sessions. b The X-axis represents the number of days of sucrose self-administration training. The Y-axis represents the number of food pellets acquired in 1 h. After 4 days, rats were stably acquiring 100 food pellets per training session