Grant: Joint Canada-Israel Health Research Program

The human brain is composed of billions of neurons that emit unitary electrical signals called action potentials or "spikes". Spikes can be detected with electrodes implanted in the brain, opening a window to observe the neuronal basis of mental activity and on the dysfunctioning neuronal processes underlying diseases such as epilepsy. The brain is composed of different types of neurons, defined by morphology, connectivity and genetic expression. In particular, neurons of the mammalian cortex can be sub-divided into two broad classes: excitatory and inhibitory. Excitatory cells integrate information from multiple local and remote sources, distribute information to local targets, convey messages across regions of the nervous system, and form a fairly uniform class of cells. In contrast, inhibitory neurons are more diverse and perform multiple tasks in neuronal networks: they control the input and output of the circuits, influence mutual activity, pace neuronal rhythms, and orchestrate the communication between brain areas. Alteration in the function of inhibitory cell networks can lead to debilitating neurological disorders, such as observed in epilepsy. Using cutting-edge tools in electrophysiology, optics, genetics, and signal processing, we will characterize the distinct electrical signatures of different cell types, detect, identify, and classify their spiking activity in real-time. This project will lay the ground for the understanding of how neuronal networks operate in healthy brains, and how they are affected in neurological disorders. It will also enable the development of the next generation of closed-loop research and therapeutic tools, in which intervention will be conditioned on the immediate detection of pathological brain signals.