Neuronal Electrical Activity in Neuronal Networks Induced by a Focused Femtosecond Laser.

The spatial propagation of neuronal activity within neuronal circuits, which is associated with brain functions, such as memory and learning, is regulated by external stimuli. Conventional external stimuli, such as electrical inputs, pharmacological treatments, and optogenetic modifications, have been used to modify neuronal activity. However, these methods are tissue invasive, have insufficient spatial resolution, and cause irreversible gene modifications. To establish neuronal stimulation with less invasiveness and higher spatial resolution, we propose and demonstrate single-neuron stimulation using a focused femtosecond laser. Fluorescence Ca ²⁺ imaging and microelectrode array recordings of extracellular potentials revealed Ca ²⁺ influx into the target neuron and high-frequency electrical responses after laser irradiation. These results indicate that femtosecond laser-induced neuronal electrical activity has a greater number of electrical spikes, lasts longer after stimulation, and propagates to a region more distant from the target neuron compared with the properties evoked by electrical stimulation. Focused femtosecond laser-induced stimulation can be a promising tool for stimulating single neurons in neuronal networks.
Competing Interests: The authors declare no competing financial interest.
(© 2024 The Authors. Published by American Chemical Society.)