Probabilistic Selection Task (PST).

<p>A. One training trial in the PST. After fixation, two symbols were presented and participants selected one symbol within 1s. After 1s positive or negative feedback was presented based on the reward probability associated with the selected symbol. RT = response time. B. Reward probabilities associated with each pair and symbol. The symbols associated with each reward probability were randomized between participants.</p

Fitted model parameters separately for approach and avoidance learners.

<p>Mean ± SEM.</p

Behavioural data (Mean ± SEM).

<p>A. Performance as a function of training. Performance improved equally for participants in the different groups as training progressed. B. Approach and avoidance performance during testing. Approach learners were relatively better at selecting the A symbol, as compared to rejecting the B symbol, while avoidance learners displayed the reverse trend. Importantly, this interaction simply reflects the assignment of participants to different groups based on their relative performance on selecting the A-rejecting the B symbol. However, approach learners were also better at selecting the A symbol as compared to avoidance learners, while the B symbol was more frequently rejected by avoidance learners. C. Approach and avoidance learners did not differ in BAS nor BIS scores. D. Approach and avoidance learners scored higher on reward sensitivity (SR) and punishment sensitivity (SP), respectively. BAS = behavioural activation system, BIS = behavioural inhibition system, SP = sensitivity to punishment, SR = sensitivity to reward, SPSRQ = Sensitivity to Punishment and Sensitivity to Reward Questionnaire. • p< 0.10, * p < 0.05, ** p < 0.01,*** p < 0.001, ns. = not significant (p>0.05).</p

Selection rates during testing and trait scores. Mean ± SEM.

<p>Selection rates during testing and trait scores. Mean ± SEM.</p

Functional MRI responses to neutral, positive, and negative pictures.

<p>Functional MRI responses to neutral, positive, and negative pictures.</p

Model-fitted data (Mean ± SEM).

<p>A. To assess approach and avoidance learning in the working memory (WM) system, the approach/avoidance model was fit to participants’ behaviour during the training phase [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166675#pone.0166675.ref012" target="_blank">12</a>]. Model-derived proportion of correct selections during the training phase is displayed by the lines, while actual behaviour is displayed by the circles. B. Approach and avoidance learning rates for the WM system. Approach and avoidance learners did not differ in the learning rates for the WM system. C. To assess approach and avoidance learning in the Habitual learning system, the approach/avoidance model was fit to participants’ behaviour during the testing phase [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166675#pone.0166675.ref012" target="_blank">12</a>]. Model-derived proportion of correct selections during the training phase is displayed by the lines while actual behaviour is displayed by the circles. D. Approach and avoidance learning rates for the Habitual learning system. Approach learners displayed relatively slower learning rates from positive feedback (<i>α</i>_{<i>Approach</i>}) as compared to negative feedback (<i>α</i>_<i>Avoid</i>), while avoidance learners displayed the reverse trend. <i>α</i>_{<i>Approach</i>} = learning rate following positive feedback, <i>α</i>_<i>Avoid</i> = learning rate following negative feedback. • p< 0.10, * p < 0.05, ** p < 0.01, ns. = not significant (p>0.05).</p

Event-related potentials (ERP) as well as the individual and statistical topographical maps following the presentation of the initial cue picture.

<p>Statistical analysis yielded no significant channels or time points for the duration of the ERP. A. Averaged waveforms from three distinct regions of interest for each experimental group. Colored shaded area indicates the standard error for each sample for each group. B. Topography of statistical differences at 500</p

Functional MRI responses to positive vs. negative pictures.

<p>Functional MRI responses to positive vs. negative pictures.</p

Ability to Maintain Internal Arousal and Motivation Modulates Brain Responses to Emotions

<div><p>Persistence (PS) is defined as the ability to generate and maintain arousal and motivation internally in the absence of immediate external reward. Low PS individuals tend to become discouraged when expectations are not rapidly fulfilled. The goal of this study was to investigate whether individual differences in PS influence the recruitment of brain regions involved in emotional processing and regulation. In a functional MRI study, 35 subjects judged the emotional intensity of displayed pictures. When processing <i>negative</i> pictures, low PS (vs. high PS) subjects showed higher amygdala and right orbito-frontal cortex (OFC) activity but lower left OFC activity. This dissociation in OFC activity suggests greater prefrontal cortical asymmetry for approach/avoidance motivation, suggesting an avoidance response to aversive stimuli in low PS. For <i>positive</i> or <i>neutral</i> stimuli, low PS subjects showed lower activity in the amygdala, striatum, and hippocampus. These results suggest that low PS may involve an imbalance in processing distinct emotional inputs, with greater reactivity to aversive information in regions involved in avoidance behaviour (amygdala, OFC) and dampened response to positive and neutral stimuli across circuits subserving motivated behaviour (striatum, hippocampus, amygdala). Low PS affective style was associated with depression vulnerability. These findings in non-depressed subjects point to a neural mechanism whereby some individuals are more likely to show systematic negative emotional biases, as frequently observed in depression. The assessment of these individual differences, including those that may cause vulnerability to depressive disorders, would therefore constitute a promising approach to risk assessment for depression.</p></div

Event-related potentials (ERP) as well as the individual and statistical topographical maps for three maximum significance points of condition effects.

<p>Top section shows the early condition differences (peaking at 110 ms and 170 ms), in a representative channel over posterior electrodes. Middle section show the later conditional differences with variations in both topography and amplitude of the ERPs. Neutral pictures provoke left-posterior peaks while humorous feedback induces a fronto-central peak topography. Statistical differences are indicative of these peaks. Lowest bar shows the conditional effect of the late positive potential. Black bars over the ERP indicate significant time points for this channel whereas yellow and red areas in the TFCE_F topography indicate significant channels.</p