Whole-cell patch clamp for monitoring low--energy focused ultrasound (LEFUS)-induced electrical activity in individual neurons

Abstract

The objective of this project was to integrate a LEFUS-system to a patch-clamp platform for exploration of LEFUS-modulated and/or -stimulated electrophysiological responses from individual cultured neurons. Mouse primary neurons and human neural progenitor cells were cultured and plated onto 35-mm diameter Petri dishes. A whole-cell patch-clamp setup in current-clamp mode was used to record electrophysiological activity generated by the neurons. The LEFUS system consisted of a 2.2-MHz planar transducer (diameter: 10-mm), administering 0.5–10 ms pulses at pressures of 6–50 kPa. Neuromodulation studies consisted in measuring changes in the activation threshold to electrical stimulation (current density required to trigger an action potential: AP) in LEFUS-treated neurons. Neurostimulation experiments consisted in measuring electrophysiological responses to LEFUS exposures in the form of triggered APs or electrical discharges from the patched neuron. Neuromodulation results showed that the activation threshold required for triggering APs could be either elevated or lowered by approximately 25% following LEFUS treatment. In neurostimulation experiments, LEFUS pressures of 25 kPa and pulse durations of 10 ms were sufficient for either disturbing the membrane potential of the cell and, occasionally, depolarizing the neuron by approximately 70 mV. [This project was supported by the French National Research Agency (ANR-16-TERC-0017), LabEx DevWeCan, and Focused Ultrasound Foundation (Centers of Excellence).]