Subventions et des contributions :

Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023)

Rhythms are present in most if not all living organisms. By interfering with these rhythms in clever ways, one can learn how these oscillations emerge, what they mean, and how one could control them. In this respect, the brain is no different. Brain rhythms, which reflect the activity of synchronized groups of neurons, are implicated in many if not all neurocognitive functions, such as attention, sleep and memory. Recently, the interaction between these oscillations and electrical stimulation has raised particular attention: weak electric fields – applied at a particular pace - can not only influence single neurons, but also control the way they synchronize and communicate with each other, directly engaging brain rhythms. Capitalizing on this, stimulation can be tuned to modulate brain oscillations, influencing perception and cognitive performance, effectively making stimulation a potential means of controlling - or restoring – neural circuits’ function. This approach has become increasingly popular to support a variety of interventions, notably to treat neurological disorders like depression and Parkinson, for instance.

But the brain is not a passive receiver. Like a forced pendulum, the effect of stimulation depends not only on neural circuits themselves, but also on their dynamic state. Converging lines of evidence indicate that stimulation efficacy to entrain brain oscillations and induce outlasting responses (sustained activity persisting once stimulation has been turned off) is gated by neural excitability, which leads to highly variable outcomes. This variability constitutes one of the main limitations to the optimization and development of new stimulation methods allowing experimentalists to probe neural circuits at a functional level based on the selective manipulation of brain rhythms.

This interdisciplinary program seeks to overcome these limitations. We will develop and study neural circuit models to understand how oscillations arise in the cortex and learn to better control them by analyzing the mechanisms involved at various spatial and temporal scales. Using mathematics and computer simulations in conjunction with experimental data, this project will study the influence of varying electric fields on single cells, and build on this to better understand how periodic stimulation combines with cortical brain rhythms, both during and after stimulation. By focusing on oscillations, this program will provide new vistas on how to efficiency engage and interrogate neural circuits – and improve our understanding of information processing in the brain. Learning how to entrain, control and even imprint oscillatory activity using well-chosen stimulation waveforms would represent a major step forward engaging neural circuits from a functional level and could open up many exciting applications in neuroscience and biomedical engineering.