The neurobiology of decision making: A window on cognition
4:00 pm, December 6^th, 2022

A decision is a deliberative process leading to a commitment to a categorical proposition or plan of action. For example, a jury takes time to weigh evidence for alternative interpretations before settling on a verdict. In this lecture I will describe advances in our understanding of how deliberation is implemented by the brain and how the brain terminates deliberation to render a choice. A common framework, termed bounded evidence accumulation, or bounded drift-diffusion, accounts for the speed, accuracy and confidence of perceptual decisions. Recent advances in high density neural recording allow us to measure the stochastic drift-diffusion signal giving rise to a single decision. The technology also facilitates simultaneous recording from populations of functionally related neurons in the parietal cortex and the superior colliculus—two strongly connected nodes of the decision macro-circuit. These experiments reveal distinct operations in the two areas—an observation that was not apparent from data averaged over many decisions. This is an example of the the promise of high density neural recordings, but I will also share concerns about potential pitfalls, namely, the false allure of high dimensional neural representation.

Consciousness and free will viewed through the lens of decision making
4:00 pm, December 7^th, 2022

Building on the foundation of the previous lecture, I will shape the window on cognition into a lens through which seemingly elusive problems may be rendered conspicuous. I will present experimental evidence that the transition from non-conscious mental processing to conscious awareness is, in essence, a decision. The experiment uses Libet’s mental chronometry, so it also touches on the topic of free will and responsibility. I will expand on the intentional—as opposed to representational—framework for the brain’s computational architecture, introduced in Lecture 1, to sketch a view of knowledge and phenomenology as affordance, focusing mainly on the parietal cortex. All experiences afford the possibility of reporting to another agent—or to oneself in the future. I will explain why this special “reporting affordance” brings consciousness into focus.