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Bercovici, Debra A.

University of British Columbia

Behavioural flexibility is an executive function which relies on the ability to adjust goal-directed actions amid changes in environmental conditions. This capability can be measured using decision-making tasks which involve weighing costs/benefits to make choices that optimize long-term utility. It can also be measured using rule-shifting tasks which involve updating choice strategies following changing rules. The prelimbic (PL) subregion of the rodent prefrontal cortex has been implicated in regulating aspects of these two types of tasks. In Chapter 1, we summarize the existing research examining the role of the PL in regulating behaviour. In Chapters 2 and 4, we use optogenetics to inhibit PL neural activity during discrete task events to determine how phasic neural activity facilitates risk/reward decision-making and set-shifting respectively. Results showed that in risk/reward decision-making, pre-choice suppression reduced bias towards more preferred/higher utility options. Inhibition during risky “losses” induced a similar profile due to the impact of “losses” being amplified or diminished, relative to the context. Inhibition during large or small reward receipt reduced risky choice when this option was more profitable, suggesting these signals act as a relative value comparator signal that augments incentive for larger rewards. Conversely, in a rule-shifting task, we found that response-related activity plays a targeted role in establishing a new rule following a shift. Additionally, PL phasic activity during cue presentation was found to be crucial for directing attention to the visual cue when that stimulus was relevant to the current rule condition. In Chapter 3, we used pharmacological inactivations of the PL across 2 different variations of a rule-shifting task to understand which task variables are dependent on PL functioning. It was found that with increased task difficulty, successful shifting behaviour is dependent on PL activity. In particular, when animals were in the early stages of learning to perform multiple rule shifts within a session, PL is vital for optimally updating information about changing rules and keeping track of which rules have already occurred each day. These findings reveal multifaceted contributions by the PL in assigning context to the decision space which facilitates decision-making under flexible conditions.

Text

2022-12-06

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83359

Psychology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/