Better than expected: a simultaneous PET/fMRI study of how prediction errors shape long-term fear reduction

Learning that once threat-predicting objects now are safe can be achieved through fear extinction.

Principles of fear extinction underlie exposure therapy, often used to treat anxiety disorders by repeatedly presenting a feared object. Key to fear extinction is the prediction error triggered by omission of the expected aversive outcome.

Animal studies have linked extinction prediction errors to dopaminergic signaling in the ventral striatum, but it is not known if this holds in humans or if the neural basis are affected in patients with anxiety disorders.

Current recommendations advocate maximizing prediction errors to form a new inhibitory safety memory, but inhibitory memories are labile and return of fear common. Smaller prediction errors may preferentially trigger fear memory updating and reduce long-term fear more reliably.

This project will use cutting-edge simultaneous positron emission tomography (PET) of dopamine release and functional magnetic resonance imaging (fMRI) to delineate the neural basis of extinction prediction errors and uncover anxiety-related changes in these processes. We will also test the effects of smaller extinction prediction errors on long-term fear reduction.

The project will run for 3-years and provide a unique understanding of the basic mechanisms and neural basis of extinction prediction errors and if these are affected in patients with anxiety disorders, as well as deliver a novel alternative to induce more robust long-term fear reduction.