Progress in Neuroscience Seminar Series: A Synaptic Mechanism for Encoding Time within Neural Circuits

David A. DiGregorio, PhDSenior Scientist Head of the laboratory of Synapse and Circuit Dynamics Pasteur Institute, CNRS, Paris, France Abstract: Sensations, thoughts, and actions are dynamic events that require the brain to encode the passage of time. For many tasks, such as playing music or sports, accurate execution requires the precise estimation of time intervals in the range of milliseconds to seconds. But how neuronal elements within brain circuits represent “time” is not understood. The cerebellar cortex is a prototypical brain circuit important for fine-tuning precise motor and cognitive behaviors on the subsecond time scale. Synaptic connections between neurons change their strength dynamically during brief bouts of activity, and we hypothesize that they could therefore act as a cellular substrate for encoding time within neural networks. I will review our experimental findings describing the characterization of synaptic diversity within the cerebellum, the molecular underpinnings of such diversity, and the computational value of synaptic diversity for encoding time within neural circuits. Rebola, N., Reva, M., Kirizs, T., Szoboszlay, M., Moneron, G., Nusser, Z. and DiGregorio, D.A. Distinct nanoscale calcium channel and synaptic vesicle topographies contribute to the diversity of synaptic function. Neuron, 104(4): 693-710 (2019). Chabrol, F.P., Arenz, A., Weichert, M.T., Margrie, T.W. and DiGregorio, D.A. Synaptic diversity enables temporal coding of coincident multisensory inputs in single neurons. Nature Neuroscience Mar 30. doi: 10.1038/nn.3974 (2015).