Brain-on-a-chip: Are we there yet?
In this talk, I will outline our efforts to understand how the brain works via two state-of-the-art technological platforms based on photonics and nanostructured semiconductor devices (a.k.a. Brain-on-a-chip). We focus our efforts to analyse the computational properties of single brain cells (or neurons) and how these cells grow to form networks and eventually function as a circuit. To analyse the function of single neurons, 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 multiple foci from a single laser. Each focus can be used as a light probe to stimulate and/or record neuronal activity. To analyse the development of multiple neurons forming circuits, we artificially grow brain cells on a semiconductor wafer patterned with nanowire scaffolds. From a fundamental perspective, we aim to investigate the structural significance of nanoscale topographies for guiding neurite outgrowth. We show that isotropic arrangements of indium phosphide InP nanowires guide neurite growth and aid in forming circuits with neighboring neurons. Multiple neurons with neurites guided by the topography of the nanowire scaffolds exhibit synchronized network activity, implying intercellular communications via synaptic connections. Photonics in combination with growing brain cells "on a chip" can lead to new insights on the function of individual neurons and how they form and function as neuronal circuits.