In Vivo Calcium and Neurotransmitter Fluorescence Imaging in Acute Models of Epilepsy

A major obstacle in treating epilepsy is a poor understanding of how seizures start and propagate. A collapse of inhibition is thought to occur at the transition from physiological brain states to seizures, but why and how this happens is unclear. While extracellular electrical recording in vivo is an important method for studying seizure generation and propagation at the network level, its poor spatial resolution and its limited ability to report trans-membrane potentials in different cell types does not readily allow the transition to seizure states to be studied mechanistically. New genetically encoded optical sensors enable cell-type specific monitoring of neuronal activity as well as neurotransmitter and neuromodulator concentrations with good spatiotemporal resolution. Here, we describe methods to image calcium, GABA, and glutamate transients, simultaneously with electrographic recordings in vivo, in acute mouse models of epilepsy.