Triggering action potentials of a single neuron by multiphoton excitation elicits visually guided behavior

Precise control of the firing of an individual neuron in vivo is a key technology to neuroscience. The laser-induced ion channel opening makes it possible to depolarize neurons and trigger the firing. In this study, we present a noninvasive, opsin-free photostimulation method for activating an individual neuron within the primary visual cortex (V1). This activation is achieved through the transient local scanning of a tightly focused femtosecond laser on the soma of the target neuron that opens the store-operated calcium channels by multiphoton excitation, induces Ca2+ influx, and depolarizes the neurons to trigger action potentials (APs) firing. In the absence of any visual stimuli, the isolated activation of an individual neuron in a cortical ensemble in layer 2/3 of V1 is sufficient to elicit visually guided specific behaviors in awake mice, without co-activating other neurons in the ensemble. Remarkably, the disruption of a single neuron within the ensemble temporarily paralyzes the entire ensemble and suspends behavioral responses to visual stimuli. However, the ensemble rapidly recovers its responsiveness and function. In general, this opsin-free photostimulation method activates targeted individual ensemble neurons in visual cortex of awake mice enabling firing APs and eliciting behaviors. Precise control of individual neuron firing is key for neuroscience. Here, the authors show a novel opsin-free photostimulation method that activates single neurons in vivo by femtosecond laser scanning-induced Ca2+ influx and action potential firing.