A novel control software that improves the experimental workflow of scanning photostimulation experiments

Abstract

Optical uncaging of caged compounds is a well-established method to study the functional anatomy of a brain region on the circuit level. We present an alternative approach to existing experimental setups. Using a low-magnification objective we acquire images for planning the spatial patterns of stimulation. Then high-magnification objectives are used during laser stimulation providing a laser spot between 2 microm and 20 microm size. The core of this system is a video-based control software that monitors and controls the connected devices, allows for planning of the experiment, coordinates the stimulation process and manages automatic data storage. This combines a high-resolution analysis of neuronal circuits with flexible and efficient online planning and execution of a grid of spatial stimulation patterns on a larger scale. The software offers special optical features that enable the system to achieve a maximum degree of spatial reliability. The hardware is mainly built upon standard laboratory devices and thus ideally suited to cost-effectively complement existing electrophysiological setups with a minimal amount of additional equipment. Finally, we demonstrate the performance of the system by mapping the excitatory and inhibitory connections of entorhinal cortex layer II stellate neurons and present an approach for the analysis of photo-induced synaptic responses in high spontaneous activity.