Cerebellar and cerebro-cerebellar networks across the millisecond and circadian timescales

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This research program aims at understanding how brain circuits functionally coordinate together to optimize movement, at the millisecond level as well as throughout the day. Brain areas involved in movement, such as the cerebellum, basal ganglia, and the cerebral cortex, interact on a fraction-of-a-second basis, prior to movement, interact to improve the exchange of information, and fine-tune the chosen motor responses. Many results point to a role of oscillatory activity in this communication process. Having shown that these neurophysiological oscillations are affected by circadian rhythms, it is of high interest to see how they relate to functional tasks, and how perturbing these oscillations can affect performance. With the cerebellum as starting point, we will study how the interaction between these brain areas change on those two timescales. The first line of research will focus on how these brain areas interact in a timed licking task to a sound or somatosensory cue. Licking is a well described natural rhythmic behaviour in rodents. We have designed a "lickometer" that can precisely measure the licking behaviour and serve to describe how these brain circuits interact prior to movement onset. Results from this line of research will provide how local circuits in the cerebellum, as well as long-range connections, interact to support interval timing. The second line of research will touch on the circadian rhythmicity of these communication mechanisms, focusing on how these brain systems likely interact. We will measure how the cerebellum, striatum, and cortex interact in the timed licking task, at different periods of the 24-hr day. The relation with the circadian patterns of the molecular clocks will be established as well. We will study how this affects the differences in wave activity, in the coherence between signals, or even how the units are influenced by the local oscillations. The third line of research touches on perturbing these communication mechanisms, via cerebellar electrical stimulation. With theta/gamma rhythmic stimulation, we will attempt to modulate inter-area communication and affect timed licking performance. This will add a more causal angle to the interpretation of oscillations modulating local circuits and more distant interactions. Multiple lines of inquiry can be added to these shorter term aims, all to better understand basic principles of inter-structure neural communication. By combining the behavioural and daily approaches, it addresses the modes of communication on the moment-to-moment and circadian scales. This new perspective will serve to develop new hypotheses on neural communication by populations of neurons across different structures.