It is generally assumed that criticality and metastability underwrite the brain's dynamic repertoire of responses to an inconstant world. From perception to behavior, the ability to respond sensitively to changes in the environment -and to explore alternative hypotheses and policies -seems inherently linked to selforganized criticality. This chapter addresses the relationship between perception and criticality -using recent advances in the theoretical neuroscience of perceptual inference. In short, we will see that (Bayes) optimal inference -on the causes of sensations -necessarily entails a form of criticality -critical slowing -and a balanced synchronization between the sensorium and neuronal dynamics. This means that the optimality principles describing our exchanges with the world may also account for dynamical phenomena that characterize self-organized systems such as the brain.This chapter considers the formal basis of self-organized instabilities that enable perceptual transitions during Bayes-optimal perception. We will consider the perceptual transitions that lead to conscious ignition [1] and how they depend on dynamical instabilities that underlie chaotic itinerancy [2, 3] and self-organized criticality [4][5][6]. We will try to understand these transitions using a dynamical formulation of perception as approximate Bayesian inference. This formulation suggests that perception has an inherent tendency to induce dynamical instabilities that enable the brain to respond sensitively to sensory perturbations. We review the dynamics of perception, in terms of Bayesian optimization (filtering), present a formal conjecture about self-organized instability, and then test this conjecture, using neuronal simulations of perceptual categorization.
Perception and Neuronal DynamicsPerceptual categorization speaks to two key dynamical phenomena: transitions from one perceptual state to another and the dynamical mechanisms that permit Criticality in Neural Systems, First Edition. Edited by Dietmar Plenz and Ernst Niebur.