The Role of the Ventral Pallidum-Nucleus Accumbens Circuit in Fear Conditioning

Science Center A154

Previous research on the neural circuitry of the reward system has identified the nucleus accumbens (NAc), the ventral pallidum (VP), and dopamine projections to these structures from the ventral tegmental area (VTA), as key players in the reward and motivation system. Specifically, the circuitry between the NAc and the VP is crucial for sign-tracking, a well known phenomenon in which, when a conditioned stimulus and reward are continuously paired, the value of the reward is transferred to the stimulus. Sign-tracking can be most clearly observed in the behavior of individuals with drug addiction, where the value of the reward (the drug) is transferred to a previously neutral stimulus (say a needle, a beer commercial, etc), resulting in cravings and reward seeking behavior. The same attribution of value can be observed between conditioned stimuli and aversive events. However, no research has been done to determine if the same brain areas responsible for sign tracking are also responsible for assigning value to aversive events. The present experiment will use rats and a fear paradigm to investigate the neural circuit responsible for assigning value to stimuli of aversive events, with the hypothesis being that the circuit responsible for this is the same circuit that functions for the reward system as recent work has demonstrated.