Online ESI Lecture by Eric Lowet

Probing neural synchronization with optical techniques

Electrophysiology represents to date the main venue to study the synchronization of neurons within and across brain areas. Recent advances in optical calcium and voltage fluorescence imaging have opened new exciting ways to study neural synchronization at high spatial and temporal resolution. I will first discuss calcium imaging and demonstrate that it can be combined with a high-density transparent EcoG array to study the relationship between calcium responses and the LFP rhythms during mouse behavior. I will then introduce cellular voltage imaging using the SomArchon fluorescent protein. This technique allows optical recording of action potentials and subthreshold fluctuations of dozens of neurons simultaneously in behaving animals. I will present recordings that were collected with a digital-mirror-device (DMD) that splits the laser beam to target specifically neurons somas. Further, combined with optogenetics, I will present preliminary data that show emergence of subthreshold theta rhythms in single CA1 hippocampal cells and how it might underlie theta phase precession relative to the LFP theta. In the last part of the talk, I will argue that these new powerful ways of recording and manipulating neural circuit dynamics will only be fruitful when combined with an understanding of dynamical system theory.