The department of Anatomy & Neurobiology will host guest speaker Dr. Krishna Jayant, an assistant professor from Purdue University.

A translaminar space-time code supports touch-evoked traveling waves

Traveling waves in mammalian cortex mediate vital aspects of animal cognition, such as stimuli perception and working memory. Theoretical results suggest that these waves preserve timing and are critical for plasticity across long-range neural circuits. Therefore, revealing the circuit mechanisms underlying sensory-evoked traveling waves is critical to understanding the neural basis of sensory perception. In this talk, I will describe our recent efforts in using 2D nanotextured transparent ECoG style electrodes to map circuits orchestrating wave dynamics. Specifically, by simultaneously mapping local-field-potentials and cellular ensemble dynamics (via 2P calcium imaging), we will describe the circuit features tied to traveling waves under active and passive whisker touch. We will show that in awake mice, both passive and active whisker touch elicited traveling waves within and across barrels, with both an early and late component lasting hundreds of milliseconds.  Strikingly, wave dynamics reflected the value of the tactile stimulus, and was found to be shaped by reinforcement learning. We will also describe how the late wave component is i) strongly modulated by motor feedback, ii) complements a sparse ensemble pattern across layer 2/3 which we resolved via a balanced-state network model with distributed top-down feedback, and iii) aligns with regenerative Layer 5 apical dendritic Ca²⁺ spikes. Our results establish a model in which translaminar spacetime patterns, organized by motor cortical feedback, sculpt touch-evoked traveling waves.