Neural mechanisms of flexible visual-oculomotor decision rules

PROJECT SUMMARY Visual decision-making in the brain is thought to depend on two behaviorally distinguishable computational components: one that converts uncertain visual inputs into a decision variable, and a second that applies a rule to the decision variable to commit to a choice. Our long-term goal is to understand the neural mechanisms that

implement these computational components of high-order visual processing, which represent key building blocks of cognition. Here we propose to examine where and how visual decision rules are implemented in the brain. We build on three primary innovations: 1) a novel theoretical framework predicting that normative decision rules

tend not to be static, as prescribed in many commonly used decision models, but rather dynamic with flexible adjustments both within and across decisions; 2) a novel task design that allows us to control the decision variable and measure decision commitment directly for each decision; and 3) measurements and manipulations

of neural activity at multiple cortical and subcortical components of a key oculomotor pathway to assess their relative contributions to implementing and updating flexible decision rules. We have three Specific Aims. Aim 1 is to characterize flexible decision rule use by monkeys. Aim 2 is to identify correlative relationships between

neural activity in the oculomotor pathway and decision rules on single trials. We targe the frontal eye field and lateral intraparietal area of the cortex; the substantia nigra pars reticulata, which is a major output structure of the oculomotor basal ganglia; and the superior colliculus, which receives input from the other three regions. Aim

3 is to identify causal relationships between neural activity in these brain regions and decision rules on single trials. Results from the proposed project will provide new, theoretically motivated, and empirically grounded insights into circuit mechanisms that control a major building block of deliberative information processing in the

brain: the rules that govern when and how to end the deliberations and commit to an action. These results will help to provide a solid foundation for investigating cognitive impairments associated with dysfunction of the cortico-basal ganglia pathway.