Spontaneous and Evoked Calcium Waves Reveal State Dependent Functional Connectivity Changes in the Developing and Adult Mouse Cortex

Abstract

During development, and into adulthood, the mouse cortex exhibits propagating waves that span the entire cortex. These waves are typically observed as a pattern whereby local cortical activity is followed by activation in adjacent areas. This leads to a propagating chain reaction that engages the entire cortex in a spatio-temporally coordinated manner. Typically in adulthood these waves are associated with slow wave sleep where they have been implicated in long term memory consolidation. During cortical development, previous studies had observed these waves only in slice preparations and their function was less clear, however they are currently thought to be linked to neuronal migration and maturation. Study of these waves had been limited in some part due to challenges associated with observing and quantifying their complex dynamics including propagation patterns and brain/behavior state dependencies. Here I present three studies to address these challenges in order to help further elucidate the nature and function of these pan-cortical waves. First, we use different modes of anesthetization in adults to determine the state dependent dynamics of local and propagating activity, both spontaneous and sensory evoked. Second, we make the first observation of developmental waves in vivo establishing the timeline of emergence, their state dependence, and electrical signature. Finally we explore the utility of the finite-time Lyapunov exponent to visualize propagating activity and capture novel insights into the structure of waves.