Adolescent risk taking, dopamine signaling, and cocaine self-administration: a vicious cycle

Abstract

Risky Decision-making Task: Male Long-Evans rats (age P25, n=54) were trained in the Risky Decision-making Task in standard behavioral test chambers. Each session in the task was 40 min in duration and consisted of 5 blocks of discrete trials, on each of which rats could choose between one of two response levers. A press on one lever resulted in delivery of one food pellet (the small, safe reward). A press on the other lever resulted in delivery of three food pellets (the large reward); however selection of this lever was also accompanied by a possible 1 s footshock (0.35 mA) contingent on a preset probability specific to each trial block (0, 25, 50, 75, and 100%, respectively). Prior to cocaine self-administration, rats were trained on the task for 25 sessions to achieve stable performance. A subgroup of rats (n=12) were sacrificed at this time point, and were prepared for in situ hybridization.