EEG oscillatory activity associated to monetary gain and loss signals in a learning task: effects of attentional...

This study investigated the influence of individual differences in attentional impulsivity (Att-Imp), learning ability, and learning practice on oscillatory activity and phase synchrony responses to monetary gain and loss signals during an instrumental-learning task in healthy women. We used a trial-by-trial wavelet-based time-frequency analysis of the electroencephalographic (EEG) signal to provide amplitude and inter-site phase synchrony measures from 30 electrodes in theta (4-8 Hz, 350-500 ms), alpha (8-12 Hz, 100-200 ms), beta (13-25 Hz, 100-200 ms), and gamma (30-40 Hz, 350-450 ms) time-frequency ranges. Oscillatory amplitude and inter-site phase synchrony were both greater following loss signals as compared to gain signals in theta, beta, and gamma frequency bands. Low Att-Imp subjects had higher theta activity within a 350-500 ms time window over frontocentral, and centroparietal sites than high Att-Imp subjects. Monetary gain signals elicited higher theta and gamma activities in high Att-Imp individuals and loss signals elicited higher activities to loss signals in low Att-Imp individuals. Good learners showed enhanced intrahemispheric theta synchrony between frontoparietal, and fronto-occipital sites to monetary loss compared to gain signals. In good learners, monetary loss produced an increase of gamma synchrony that enhanced in the second stage of learning. In low Att-Imp individuals, there was a reduction of theta synchrony during the second stage, as compared with the first stage of learning, between temporal, parietal and fronto-parietal brain regions. These findings may offer valuable clues to understand outcome processing, attentional impulsivity, and learning ability. We propose that the punishment-related theta and gamma waves play a leading role in learning process.