The Role of Task Events, Environmental Uncertainty, and Striatal Activity in Modulating Decision Strategies

 To maximize rewards, organisms must adapt their decision strategies to  environmental events and conditions. For example, one might hypothesize that rewarded  actions should be repeated, whereas behavior should become more variable following  unrewarded actions. The level of outcome responsivity, however, should shift depending on  the environmental conditions, such as the stability of the environment or reliability of  action-outcome contingencies. We propose that all decision strategies can be described  along this outcome responsivity axis.  These strategies range from highly outcome  responsive (such as the win-stay, lose-shift strategy described above) to various low  responsivity strategies (such as biased choices or random exploration). This thesis  investigates specific task events and environmental conditions that trigger these distinct  strategies.  Second, we highlight the striatum as a key brain region for modulating the  “knob” of outcome responsivity.  Finally, the thesis puts forth the notion of cognitive effort to-reward ratio maintenance as an explanation for the observed strategy shifts.