Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.29.176974v1?rss=1 Authors: Vinner, E., Matzner, A., Belelovsky, K., Bar-Gad, I. Abstract: Motor tics, the hallmark of Tourette syndrome, are modulated by different behavioral and environmental factors. A major modulating factor is the sleep-wake cycle in which tics are attenuated to a large extent during sleep. This study investigates the neural mechanisms underlying tic reduction during sleep in an animal model of chronic tic disorders. We recorded the neuronal activity during spontaneous sleep-wake cycles throughout continuous GABAA antagonist infusion into the striatum. Analysis of video streams and concurrent kinematic assessments indicated tic reduction during sleep in both frequency and intensity. Extracellular recordings in the striatum revealed a dissociation between motor tic expression and their macro-level neural correlates (LFP spikes) during the sleep-wake cycle. LFP spikes persisted during tic-free sleep and did not change their properties despite the reduced behavioral expression. Local, micro-level, activity near the infusion site was phase-locked to the LFP spikes during wakefulness but this locking decreased significantly during sleep. These results suggest that while LFP spikes, which are generated as a result of abnormal and focal disinhibition in the striatum, encode motor tic feasibility, the behavioral expression of tics requires local striatal neural activity entrained to the LFP spikes, leading to the propagation of the activity to downstream targets and consequently their motor expression. These findings point to a possible mechanism for the modulation of tic expression in TS patients during sleep and potentially during other behavioral states. Copy rights belong to original authors. Visit the link for more info