Abstract
Pavlovian biases, the best known of which is the approach and engagement engendered by re-
ward predictors, is well established in animals and has been related to drug-seeking behavior. However, the
neural mechanisms underlying individual differences in the ability to overcome Pavlovian biases remains un-
clear. To address this, we scanned 74 healthy human participants with functional magnetic resonance imag-
ing while they played a pre-existing reinforcement learning task that is designed to elucidate instrumental
learning and its modulation by Pavlovian biases. Via computational modeling, we found strong behavioral
evidence for a Pavlovian bias in the face of rewards but not punishments, which was consistent with previ-
ous reports. Using model-based fMRI, we found several regions that were important for over- coming the
Pavlovian bias, including the medial prefrontal cortex (mPFC), inferior frontal gyrus (IFG), superior frontal
gyrus, and hippocampus/parahippocampal gyrus. We also found that dorsolateral PFC (DLPFC), IFG, and
superior temporal gyrus/medial temporal gyrus (STG/MTG) showed positive functional connectivity with
mPFC while subjects successfully overcame the bias. By revealing behavioral and neural measures of indi-
vidual differences in the propensity to exhibit Pavlovian biases, and a network of brain regions important
for overcoming them, this work may have important implications for predicting/preventing relapse for drug
addiction.
