Seminar: Light and nanotechnology tools for understanding the brain

Speaker

Dr. Vincent Daria

Leader of the Neurophotonics Research Group, John Curtin School of Medical Research, ANU, Australia

Abstract

I will talk about our work on the use of patterned light and nanostructured devices to understand how neurons function and form circuits. We use light not only to visualize these neurons but also to stimulate and record neuronal activity.  We produce light patterns using a programmable hologram, which projects spatially arranged multiple foci from a single laser. Each focus can induce highly localized synaptic inputs along the dendritic tree of a neuron. We analyse how the spatio-temporal organization of these patterned inputs prompt a neuron to fire an output. The light patterns can also be used for optical recording of activity from multiple neurons using a calcium indicator. To further understand the significance of dendritic trees of a single neuron, we use non-linear laser ablation to prune the dendrites. The neuron’s output and overall function in a neuronal circuit are said to be dependent on the spatial extent of its dendritic tree.  Hence, laser dendrotomy allows us to study morphology-dependent neuronal function.  To understand the development of multiple neurons forming circuits in the brain, we artificially grow cortical neurons on nanowire scaffolds. From a fundamental perspective, we aim to investigate the structural significance of nanoscale topographies for guiding neurite outgrowth and analyse its function using light. To achieve this, we use electron microscopy to monitor neuronal growth and optically record the network activity using a calcium indicator. We show that isotropic arrangements of indium phosphide nanowires guide neurite growth and aid in forming circuits with neighbouring neurons. Multiple neurons with neurites guided by the topography of the nanowire scaffolds exhibit synchronized calcium activity, implying intercellular communications via synaptic connections.  Light in combination with nanostructured devices could provide new insights on the function of individual neurons as well as formation of neuronal circuits in the brain.

Host

The Optical Society OIST Student Chapter

If you would like to meet with Dr. Daria, please contact Peter Mekhail (E-mail: simon.mekhail@oist.jp)