Learning and Action in Uncertain Environments
Successful interaction with the environment requires flexible updating of our beliefs about the world. By learning to estimate the likelihood of future events, it is possible to prepare appropriate actions in advance and execute fast, accurate motor responses. According to theoretical proposals, humans track the variability arising from dynamic environments by computing various forms of uncertainty. Several neuromodulators have been linked to uncertainty signalling but comprehensive empirical characterisation of their roles in perceptual belief updating and motor response modulation has been lacking.
In this talk, I will first present findings from a recent pharmacological experiment designed to interrogate the relative contributions of noradrenaline, acetylcholine and dopamine to human learning and action within a unified computational framework of uncertainty. Second, I will focus on the role of noradrenaline. Combining an auditory probabilistic learning task, pharmacological manipulations, pupillometry and computational modelling, I will present empirical support for the notion that pupil diameter offers an indirect measure of dynamic noradrenergic computations of uncertainty and volatility.