The Role of the N170 in Linking Stimuli to Feedback-Effects of Stimulus Modality and Feedback Delay.

With increasing feedback delay, feedback processing appears to shift from the striatum to the hippocampus. In addition, higher-order sensory areas might be involved in bridging a temporal gap between stimulus and feedback by reactivating the representation of the feedback-predicting stimulus during feedback processing. We hypothesized that the feedback-locked N170, an occipito-temporal event-related potential (ERP) component linked to higher-order visual processing, is more pronounced when delayed feedback is provided for choices between visual compared to auditory stimuli. 35 subjects completed a probabilistic feedback learning task with immediate (1 s) and delayed (7 s) monetary feedback for choices between visual or auditory stimuli. Participants successfully learned to choose the more rewarding stimuli irrespective of stimulus modality. For the N170 amplitude over the right hemisphere, we found an interaction between feedback timing and the modality of the chosen stimulus. Only for delayed feedback, the N170 was more pronounced for choices between visual than auditory stimuli. Moreover, in this condition, the N170 amplitude particularly reflected the reward prediction error (PE), with larger amplitudes for positive PEs and lower amplitudes for negative PEs. This suggests that the N170 reflects feedback-locked reactivations in higher-order visual areas mediated by the reward PE. While these effects need to be studied further, we discuss the N170 as a counterpart to the feedback-related negativity (FRN) regarding interacting influences of feedback valence, feedback timing, and PE.