Introduction

Information processing in the brain involves electrical and chemical signals which are spatially confined at the subcellular level and which occur at the time scale of milliseconds. While changes of membrane voltage and concentrations of various intracellular signaling chemicals are well characterized at the level of single cells, much less experimental data are available on the electrical and chemical signaling of multiple interacting neurons.

Aim

To bridge the gap between our understanding of signals in single neurons and of network theories, we need to monitor the dynamics of membrane voltage and chemical signals in neuronal circuits at many sites simultaneously and with high temporal resolution.

With this viewpoint, we are developing and applying innovative optical imaging techniques based on environmental-sensitive fluorescent probes. Membrane voltage, ion concentrations or second messenger levels modulate the optical properties of such probes. Furthermore, some of these probes can be genetically encoded and targeted to specific neuronal compartments. We apply these techniques in the cerebellar and cerebral cortex in order to understand the principles of the spatio-temporal information flow and its use-dependent modifications in these brain structures.

Optogenetic imaging of neuronal circuit dynamics