Vincenzo Varriale

Event-related components of the punishment and reward sensitivity

OBJECTIVE The present study investigated the properties of feedback-related negativity (FRN) and P3 component of the event-related potentials (ERPs) and their neural sources localization as neurocognitive correlates of the behavioural inhibition and behavioural activation systems (BIS/BAS). The association between BIS/BAS function and anterior cortical asymmetry was tested. METHODS Fifty right-handed women were investigated with 30-channel recordings during an instrumental Go/No-Go learning task. ERPs were elicited to feedback signals indicating monetary losses and monetary gains. Learning performance, FRN, and P3 amplitude and latency measures were calculated and related to BIS and BAS measures by means of ANOVA and correlation analysis. The neural sources of FRN and P3 components of the ERPs were estimated using LORETA software. A resting EEG-alpha-power (8-13Hz) asymmetry measure was obtained. RESULTS High levels of Reward Responsiveness (RR), a first order factor of the BAS, were associated with shorter RTs and enhanced positive feelings. The FRN was larger to signals indicating monetary Loss as compared to monetary Gain and enhanced with higher BIS and individual learning ability. Higher RR scores were related to greater left-sided resting frontal cortical asymmetry associated with approach orientation. High-RR subjects, as compared to Low-RR ones, had a smaller P3 amplitude for Go/Loss signals. The P3 latency to No-Go/Gain signals was the best positive predictor of RR. LORETA source localization for the FRN component displayed significantly higher brain electrical activity in left-fusiform gyrus and right superior temporal gyrus to monetary Loss in comparison to monetary Gain after incorrect No-Go responses. For the P3 wave, the monetary Loss produced significantly higher activations in the left superior parietal lobule, right postcentral gyrus, and in the ACC. CONCLUSION The FRN was sensitive to cues of punishment and higher BIS was uniquely related to a larger FRN amplitude on No-Go/Loss trials, linking BIS with conflict monitoring and sensitivity to No-Go cues. Furthermore, the significant interaction found between BIS and RR on FRN amplitude together with the findings linking High-RR levels with shorter RTs, smaller P3 amplitudes and enhanced positive feelings are in line with the hypothesis that both BIS and BAS have the potential to influence punishment-mediated and reward-mediated behaviour. SIGNIFICANCE Results open up new perspectives for future investigations on the relationship between BIS/BAS measures and ERP components to monetary reward during learning.

EEG oscillatory activity associated to monetary gain and loss signals in a learning task: Effects of attentional impulsivity and learning ability

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.

Pain modulation in waking and hypnosis in women: event-related potentials and sources of cortical activity.

Using a strict subject selection procedure, we tested in High and Low Hypnotizable subjects (HHs and LHs) whether treatments of hypoalgesia and hyperalgesia, as compared to a relaxation-control, differentially affected subjective pain ratings and somatosensory event-related potentials (SERPs) during painful electric stimulation. Treatments were administered in waking and hypnosis conditions. LHs showed little differentiation in pain and distress ratings between hypoalgesia and hyperalgesia treatments, whereas HHs showed a greater spread in the instructed direction. HHs had larger prefrontal N140 and P200 waves of the SERPs during hypnotic hyperalgesia as compared to relaxation-control treatment. Importantly, HHs showed significant smaller frontocentral N140 and frontotemporal P200 waves during hypnotic hypoalgesia. LHs did not show significant differences for these SERP waves among treatments in both waking and hypnosis conditions. Source localization (sLORETA) method revealed significant activations of the bilateral primary somatosensory (BA3), middle frontal gyrus (BA6) and anterior cingulate cortices (BA24). Activity of these contralateral regions significantly correlated with subjective numerical pain scores for control treatment in waking condition. Moreover, multivariate regression analyses distinguished the contralateral BA3 as the only region reflecting a stable pattern of pain coding changes across all treatments in waking and hypnosis conditions. More direct testing showed that hypnosis reduced the strength of the association of pain modulation and brain activity changes at BA3. sLORETA in HHs revealed, for the N140 wave, that during hypnotic hyperalgesia, there was an increased activity within medial, supramarginal and superior frontal gyri, and cingulated gyrus (BA32), while for the P200 wave, activity was increased in the superior (BA22), middle (BA37), inferior temporal (BA19) gyri and superior parietal lobule (BA7). Hypnotic hypoalgesia in HHs, for N140 wave, showed reduced activity within medial and superior frontal gyri (BA9,8), paraippocampal gyrus (BA34), and postcentral gyrus (BA1), while for the P200, activity was reduced within middle and superior frontal gyri (BA9 and BA10), anterior cingulate (BA33), cuneus (BA19) and sub-lobar insula (BA13). These findings demonstrate that hypnotic suggestions can exert a top-down modulatory effect on attention/preconscious brain processes involved in pain perception.