Authors: Joseph E. Dunsmoor, Marijn C.W. Kroes, Jian Li, Nathaniel D. Daw, Helen B. Simpson, Elizabeth A. Phelps
Summary: Standard fear extinction relies on the ventromedial prefrontal cortex (vmPFC) to form a new memory given the omission of threat. Using functional magnetic resonance imaging (fMRI) in humans, we investigated whether replacing threat with novel neutral outcomes (instead of just omitting threat) facilitates extinction by engaging the vmPFC more effectively than standard extinction. Computational modeling of associability (indexing surprise strength and dynamically modulating learning rates) characterized skin conductance responses (SCR) and vmPFC activity during novelty-facilitated but not standard extinction. Subjects who showed faster within-session updating of associability during novelty-facilitated extinction also expressed better extinction retention the next day, as expressed through SCRs. Finally, separable patterns of connectivity between the amygdala and ventral versus dorsal mPFC characterized retrieval of novelty-facilitated versus standard extinction memories, respectively. These results indicate that replacing threat with novel outcomes stimulates vmPFC involvement on extinction trials, leading to a more durable long-term extinction memory.
Source: The Journal of Neuroscience, 2019; 2713-18