Temporally and spatially resolved wide-field nonlinear imaging

This month we will have the pleasure to host Marie Didier from the Laboratory of Fundamental Biophotonics with the presentation entitled:

"Temporally and spatially resolved wide-field nonlinear imaging: membrane-water, a probe for neuronal membrane potentials and ionic flux at the single cell level"

For organizational purposes (if you want to eat pizza!), please confirm your participation using this Doodle.

Don’t hesitate to extend the invitation to any postdoc and colleague!

Hope to see you there,
The team of the EPFL Photonics Chapter


Abstract:

Neurons communicate through electrochemical signalling within a complex network. These signals are composed of spatiotemporal changes in membrane potentials that are traditionally measured by electrical recordings or using optical probes. Since probes are inevitable invasive and severely damaging to the cells, label-free mechanism are sought for. For many years second harmonic (SH) imaging has been a promise for delivering direct label-free neuronal membrane potential information. However, to date this promise has not been delivered, owing to the intrinsic low sensitivity of the method. Here, we demonstrate an enhanced efficiency of three orders of magnitude of wide field SH neuroimaging. With this enhanced sensitivity we propose to use membrane bound water to create membrane potential and ion flux maps. To demonstrate the concept, we perform a patch-clamp and SH imaging comparison that shows a correlation between whole neuron membrane potential changes and the square root of the SH intensity, as predicted by theory. We then use the nonlinear optical response of the membrane bound water to image spatiotemporal changes in the membrane potential and K+ ion flux of mouse brain neurons. We observe inhomogeneities that are attributable to a non-uniform spatial distribution and temporal activity of ion channels.