Adolescent neural processing differences in orbitofrontal cortex, nucleus accumbens, and dorsal striatum during motivated behavior

Adolescence coincides with increased sensation-seeking and impulsive behavior, and is often the time of symptomatic onset for psychopathologies.
We recorded single unit activity from the orbitofrontal cortex (OFC), nucleus accumbens (NAc), and dorsal striatum (DS) of adolescent and adult rats during an instrumental associative learning task.

Striking age-related differences were observed in the neural encoding of salient events, especially reward. A smaller proportion of adolescent OFC neurons were inhibited compared to that of adults during reinforcement retrieval and at other points during the task. Diminished inhibitory responses in adolescent OFC during salient events may affect the coordination of activity and ultimately neuronal processing efficiency.
Indeed, adolescent OFC neurons exhibited greater trial-by-trial firing-rate variability throughout the task. Although some processing differences were observed between adolescents and adults in the NAc, these were modest and transient. In contrast, adolescent DS neural activity was quite different from that of adults, especially in the period leading up to reward. Adolescents, but not adults, exhibited strong neuronal activation that persisted all the way to reward-retrieval.
These results demonstrate that adolescence coincides with dramatic differences in reward processing in the OFC and DS, but not NAc, indicating that the developmental trajectory is highly region-specific.

No relevant conflicts of interest declared.