Ultrasensitive fluorescent proteins for imaging neuronal activity

Abstract

Fluorescent calciumsensors arewidely used to imageneural activity.Using structure-basedmutagenesis andneuron-based screening, we developed a family of ultrasensitive protein calcium sensors (GCaMP6) that outperformed other sensors in cultured neurons and in zebrafish, flies andmice in vivo. In layer 2/3 pyramidal neurons of the mouse visual cortex, GCaMP6 reliably detected single action potentials inneuronal somata and orientation-tuned synaptic calciumtransients in individual dendritic spines. The orientation tuning of structurally persistent spines was largely stable over timescales of weeks. Orientation tuning averaged across spine populations predicted the tuning of their parent cell. Although the somata of GABAergic neurons showed little orientation tuning, their dendrites included highly tuned dendritic segments (5-40-mm long).GCaMP6sensors thusprovidenewwindowsintothe organization anddynamics of neural circuitsovermultiple spatial and temporal scales. [PUBLICATION ABSTRACT]