A key role for stimulus-specific updating of the sensory cortices in the learning of stimulus–reward associations

Successful adaptive behavior requires the learning of associations between stimulus-specific choices and rewarding outcomes. Most research on the mechanisms underlying such processes has focused on subcortical reward-processing regions, in conjunction with frontal circuits. Given the extensive stimulus-specific coding in the sensory cortices, we hypothesized they would play a key role in the learning of stimulus-specific reward associations. We recorded electrical brain activity (using electroencephalogram) during a learning-based decision-making gambling task where, on each trial, participants chose between a face and a house and then received feedback (gain or loss). Within each 20-trial set, either faces or houses were more likely to predict a gain. Results showed that early feedback processing (~200–1200 ms) was independent of the choice made. In contrast, later feedback processing (~1400–1800 ms) was stimulus-specific, reflected by decreased alpha power (reflecting increased cortical activity) over face-selective regions, for winning-vs-losing after a face choice but not after a house choice. Finally, as the reward association was learned in a set, there was an increasingly stronger attentional bias towards the more likely winning stimulus, reflected by increasing attentional orienting–related brain activity and increasing likelihood of choosing that stimulus. These results delineate the processes underlying the updating of stimulus–reward associations during feedback-guided learning, which then guide future attentional allocation and decision-making.