Learn to No Longer Be Afraid: Role for L-Dopa?

The patient undergoing behavioral treatment of a fear response learns a new adaptive response to the same stimulus. This new, inhibitory, extinction memory competes with, and does not erase, the fear memory, which can therefore recur. Researchers examined how the dopamine precursor, L-dopa, affects the return of fear in humans and in a mouse model.

A classic conditioning foot-shock model induced a conditioned response in mice, which then underwent extinction, followed by a single dose of L-dopa or saline. When the mice were placed in the conditioning cage (i.e., context) 1, 7, and 30 days later, L-dopa was associated with less spontaneous recurrence of fear, an attenuated return of contextual fear after shock reinstatement, greater immediate…