Investigating proactive and reactive modulation of reward on action inhibitory control
| Autor: | Hsin-Ju Lee, 李芯如 |
|---|---|
| Rok vydání: | 2018 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 Effective action inhibition needs a good balance of proactive and reactive control. Previous studies have used the stop-signal task to assess and evaluate proactive and reactive control for action inhibition. However, the picture that how neural mechanisms underlying these two types of control work for action inhibition is not completed yet. In this study, we use fMRI to examine neural underpinnings of (1) how proactive and reactive control works in concert to inhibit an action already planned when motivated and (2) how induced positive and negative affects exert their influence to proactive and reactive control for inhibiting an upcoming action. In Experiment 1, using reward anticipation in a stop-signal task, the motivational effects on inhibitory control was investigated. Our behavioral data supported that motivation introduces a new balance between fast response and accurate stopping. The fMRI findings back up the behavioral results. First, the frontoparietal network is involved in the establishment of balance. Next, we found motivation effects in the anterior caudate and pre-supplementary motor area (pre-SMA) for action inhibition. The former works to register motivation status, while the latter works to transform motivation into action inhibition control. The connectivity analysis indicated that the pre-SMA shows a stronger coupling with the right inferior frontal cortex (rIFG) when rewarding. Combined with the correlation of stop-signal reaction time (SSRT) and rIFG activity was disrupted in the condition with reward anticipation, we suggested a hierarchical relationship between functional roles of pre-SMA and rIFG during action inhibition. While the pre-SMA respond to proactive preparation to accommodate higher-order factors, such as motivation, for action control, the rIFG acts to participate in the execution of action inhibition. In Experiment 2, by presenting an accidental reward before a stop trial, we examined how affective responses evoked by different rewards influence inhibition control in a stop signal task. We found that SSRT reduction under both positive and negative reward conditions, as compared to the neutral condition. The fMRI results demonstrated activities in wide-spread brain regions were enhanced by reward, encompassing brain regions of visual perception, attention control, valuation, and inhibitory control. Activities in most regions were insensitive to valence polarity, suggesting bottom-up attentional deployment due to reward salience. ROI analysis revealed functional segregation in the dorsal and ventral part of medial striatum. While the ventral side encodes the reward valences, the dorsal part represents current demand of environments. Finally, we correlated the SSRT reduction with the regional activity extracted from rIFG and right pre-SMA. For the former, there was positive correlation in the PR condition. For the latter, however, there was positive correlation in the NR condition. Therefore, positive and negative rewards can affect action inhibition to a similar extent, but through different pathways. To conclude, motivation and affects induced by rewards can exert their influence on action inhibition control. Anatomically, while the function of the rIFG is closer to reactive inhibition, the role of pre-SMA is more responsive to proactive control. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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