Text

theses

ETD doctoral

The ability to perceive and exercise control over an outcome is both desirable and beneficial to our wellbeing. Organisms are biased to seek control in situations where rewards are available and such bias has been shown to recruit the ventromedial prefrontal cortex (vmPFC) and striatum. Moreover, when given control over potentially aversive outcomes, organisms increase behaviors to avoid those outcomes. These findings suggest that perceived control exerts behavioral influences in both appetitive and aversive environments. Yet, several questions remain unanswered. First, if an organism shows behavioral preference towards control in appetitive contexts, can we measure this bias and study the subjective value of control neurally? To find out, we employed the Value of Control (VoC) task where human participants were asked to make a series of binary choices between having control and no-control over a reward-seeking game. The mere presence of the control-option evoked activity in the striatum. Importantly, we extracted the positive subjective value of control and demonstrated that it was tracked in the vmPFC. Second, because control confers protective effects against behavioral passivity in aversive contexts, it remains uncertain whether it is potent enough to reverse behavioral passivity following prolonged exposure to uncontrollability. To investigate this, we employed the Control in Aversive Domain (CAD) task to examine whether the introduction of controllability can rescue participants' behavior after persistent uncontrollability. We observed that even after developing behavioral passivity, instatement of control was able to restore avoidance behavior, and this behavioral reversal correlated with participants' vmPFC activity. Third, it is unknown whether exposure to acute stress can negatively impact participants' perception of control. To study this, we subjected participants to an acute stressor prior to implementing the VoC and CAD tasks. We found that exposure to acute stress did not significantly alter participants' subjective value of control but it did induce participants to exhibit greater behavioral responses towards uncontrollable aversive stimuli. Collectively, these studies show that perceived control can bias behavior via its rewarding values and protective effects. They also highlight the role of corticostriatal circuitry in encoding control, which has important implications in our understanding of psychopathologies associated with the loss of control.

ETD_10092

doi:10.7282/t3-g0nc-wt13

Ph.D.

Includes bibliographical references

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