Investigating the neurobiology regulating cognitive effort allocation using a rodent model of cost/benefit decision making

Choosing adaptively among candidate actions requires a cost-benefit analysis, in which potential rewards are considered against the costs required to obtain them. One cost frequently encountered by humans is the cost of cognitive effort, in which executive processes spanning attention, working memory, reasoning, and the like are taxed. This form of effort is in contrast to the physical effort costs that have generally been the focus of the cost/benefit decision-making literature. This thesis reviews the currently available literature investigating the brain regions and neurotransmitter systems guiding these respective forms of decision making, and then carries out a set of experiments to further characterize the neurobiology guiding cognitive effort allocation. These experiments utilize an animal model of decision making known as the rodent Cognitive Effort Task (rCET), in which subjects decide whether to exert more attention in pursuit of larger rewards, or to obtain smaller reward for comparatively less attentional demand. In experiment 1, I use chemogenetics to downregulate cholinergic neurons of the basal forebrain as rats perform the rCET, to determine whether this neuronal population is responsible for the previously ascribed role of acetylcholine in regulating decision making with cognitive effort costs. Experiments 2 and 3 use standard inactivation techniques to investigate striatal and orbitofrontal cortex contributions to this form of decision making, and Experiment 4 uses a disconnection procedure to assess whether BLA- ACC signaling regulates willingness to apply cognitive effort. Collectively, the current findings complement existing work in the domain of physical effort allocation, and support the notion that these two forms of effort-based decision making are mediated by distinct, albeit overlapping circuitries. While this work fundamentally contributes to an understanding of how organisms navigate their environment, it also has practical utility. Indeed, work with the rCET and related cognitive effort paradigms may help identify behavioural or pharmacological therapies that can boost cognitive willingness. Alternatively, information gained may shed light on the aberrant processes underlying a blunted desire to achieve lucrative outcomes, as observed in disorders like depression, schizophrenia, and Parkinson’s Disease.