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Problem gambling (PG) is increasingly conceptualized as an addiction akin to substance abuse, rather than an impulse control disorder, however the mechanism of addiction remains unclear. Neuroimaging investigations have supported a “reward deficiency” hypothesis for PG by suggesting a blunted response to gambling, particularly in the striatum. Here we describe electrophysiological evidence of a hypersensitive response to gambling feedback in problem gamblers. Previous research in healthy participants has shown that feedback during gambling tasks triggers stereotypical neural responses including the Feedback-Related Mediofrontal Negativity (FRN), the feedback-related P300, and an increase in induced theta-band (4–8 Hz) power. We tested the theory that abnormal feedback processing characterizes brain activity in problem gamblers while gambling. EEG was recorded from non-gamblers and self-identified gamblers as they engaged in a computerized version of the Iowa Gambling Task. Feedback about valence (win vs. loss) triggered a FRN in both groups, but in gamblers this was preceded by an early-latency hypersensitive fronto-central difference to feedback. This early FRN was correlated with gambling severity and was localized to medial frontal cortex using distributed source imaging (CLARA). Gamblers also differed in responses to risk, showing a blunted P300 component and less EEG power in the theta band. Here we suggest that a more nuanced interpretation of reward deficiency is called for with respect to PG. For certain aspects of brain function, gamblers may exhibit hypersensitivity to reward feedback more akin to drug sensitization than reward deficiency. Our results also suggest that the neurologically normal brain employs dissociable systems in the processing of feedback from tasks involving risky decision making.

Attended stimuli typically evoke larger event-related potentials (ERPs) than unattended stimuli. We previously reported an exception when an optic-flow pattern is interleaved with stationary dots. Reversals of motion direction evoked a larger N200 peak when attention was directed to the stationary dots. We replicated and further characterized this result: the N200 enhancement was eliminated when the dots moved randomly rather than in optic flow. The effect was also attenuated with isoluminant stimuli. Electrical source analysis suggested the attentional modulation of a configuration of dorsal extrastriate generators. The ERP evoked by reversals of optic flow may reflect the operation of independently configurable attentional filters within visual cortex.

When participants in a gambling game are given feedback as to whether they won or lost the previous bet, a series of stereotypical brain electrical responses can be observed in the electroencephalogram (EEG) and the stimulus-locked Event-Related Potential (ERP). These include the Feedback-Related Mediofrontal Negativity (FRN), a posterior P300, and a feedback-induced increase in power at the theta (4 to 8 Hz) band over frontal scalp. Although the generators of the FRN and P300 have been studied previously, little is known about the generator of feedback-induced theta. We employed a gambling game in which participants chose either high-risk/high-reward or low-risk/low-reward bets to investigate these feedback-related responses. The FRN was not modulated by the riskiness of the bet, but both P300 and feedback-induced theta were of greater amplitude following high- relative to low-risk bets. Using a bilateral multi-source Beamformer approach, we localized the induced theta-band responses following wins and losses to partially overlapping regions in the right medial frontal cortex, possibly including the Anterior Cingulate. Using a dipole-fitting approach, we found that the generators of feedback-induced theta are anatomically distinct from those of the FRN and P300.