The Impact Of Emotion Valence On Brain Processing Of Behavioral Inhibitory Control:Spatiotemporal Dynamics

As an ability to inhibit inappropriate behaviors, behavioral inhibitory control (BIC) plays an indispensable role in adaptive living in the changing environments. Successful adaptation requires that we be selectively invoked by a context-appropriate balance of agency and inhibition. Inhibitor}’ control is a multi-domain executive function critical for flexible responsivity to changing task demands. According to the theoretical model of Norman and Shallice (1986), the behavioral inhibitory control involves multiple processes such as earlier perceptual processing, conflict detection, and later response inhibition.As is known, although the Go/Nogo task is frequently used to investigate behavioral inhibitory control(BIC) and its related neural correlates. However, as go trials involvesmotor responses whereas no go trials do not, the inhibitory control effects observed in studies using the Go/Nogo paradigm are likely to be contaminated by response-related processes, and lack of the behavioral index of BIC. Moreover, both emotion and response inhibition are characterized by involving rapid (short latency) and brief (short duration) subprocesses, some of the most important occurring within the first 600 ms after stimulus onset.Therefore, in order to unravel temporal dynamics of the emotion impact on behavioral inhibitory control, it is necessary to design a new paradigm that is able to overcome the emotion attenuation and the motor potential contamination. Firstly, emotional pictures were selected in such a way that the arousal level was overall matched across the three valence conditions, and in order to ensure its reliability, these materials were re-assessed by a large number of subjects. In experiment 1, 65 subjects were recruited to aimed at assessing the arousal and valence of pictures through using a 9 point scale (such as from "unpleasant" to "pleasant"). The results showed that three groups of deviant pictures were differed significantly in valence from one another [F(2,87)=839.934, P<0.001], but were similar in arousal [F(2,87)=1.231, P>0.05]. None of them involved the formal EEG experiment. In experiment 1, the present study used a two-choice oddball task and 18 subjects were recruited. According to the valence of the deviant stimuli, the experiment was divided into three blocks:neutral, negative and positive. Each block had 200 trials, including 170 standard and 30 deviant pictures (85% vs.15%). All subjects were told that this experiment was to investigate their ability to make a fast response selection, and their ability to inhibit the prepotent response to the frequent standard picture when the deviant appears. Behavioral results showed prolonged reaction times (RTs) and diminished accuracy rates (ACCs) for deviant than for standard stimuli, irrespective of the emotionality of deviants. For the low-frequency response to be executed, it must compete with and eventually overcome the bias toward producing the prepotent response tendency. Moreover, there were significant main effects of stimulus type, and significant stimulus and emotion interaction effects on the averaged amplitudes of the 200-300ms and 300-500ms intervals. Through analysing the deviant-standard difference ERPs that index BIC directly, we found larger N2 and smaller P3 amplitudes during the unpleasant block than during the neutral block. And the enhanced N2 amplitudes in the negative block most likely reflected the potentiation of response conflict monitoring by emotionally negative stimuli which, as indicated, is associated with enhanced attention alerting. In contrast, the task-irrelevant pleasant information did not produce such a potentiation of response conflict monitoring, probably as a result of reduced biological significance conveyed by the pleasant relative to unpleasant stimuli. The smaller P3 amplitudes for the emotionally negative information, which is associated with automatic and biased processing, is task-irrelevant and distracting in the present study, the human brain must recruit a process of cognitive control for inhibiting the interference from the unpleasant information, for the sake of achieving the task of standard/deviant distinction rapidly. The involvement of an additional cognitive control process most likely explains why the amplitudes of difference P3 that reflects processing of response inhibition was smaller during unpleasant than during the other two blocks.In summary, by synchronizing emotion induction with performance of behavioral inhibitory control, the present study developed our understanding of the emotion interaction with BIC, by showing that pleasant and unpleasant emotions are different in impact on brain processing of behavioral inhibitory control, not only in early monitoring of response conflicts but also in the late stage of response inhibition. Future studies should consider using this paradigm to investigate the temporal features of the emotion impact on BIC in patients of inhibitory control dysfunction, such as manic-depressive patients known to be worse in emotional and behavioral self regulation. This would be helpful for clarifying which stage (s) of BIC dysfunctions with emotion in these patients, which may lend an insight into the development of treatment strategies.