Figure 6.

Retzius neuron membrane potential following extended US application is influenced by prior sharp electrode impalement. A, Schematic of extended US application. Pulsed US was applied for a 20-min duration. Tones were delivered the first 10 s of each minute (tone duration = 10 s, tone frequency = 0.167 Hz). Tones consisted of 10,000 pulses of 300 cycles of 960-kHz US (pulse repetition frequency = 1 kHz, pulse duration = 312.5 μs). Pressure applied was 111 kPa in all trials. B, Schematics of trial design for extended application paradigm. Upper, Retzius neuron was impaled (blue), and resting membrane potential was recorded. The recording electrode was then removed (middle cartoon) and US was applied for 20 min. Following US application, the electrode was re-inserted into the same Retzius cell for a second baseline recording. Lower, In a different preparation, the electrode was inserted into the Retzius cell (blue) to record the resting membrane potential. As in the previous experiment, the electrode was removed before 20 min of US application (middle cartoon). After application, the contralateral Retzius cell (orange) was impaled to record baseline activity; this cell was thus not previously impaled. C, Intracellular recordings taken from the same Retzius cell before and after extended application of US demonstrating post-US depolarization of the resting membrane potential. D, Scatter plots comparing differences between pre-US and post-US membrane potential (mV) in the same cell (blue) and contralateral cell (orange). Control paradigms replaced the US application period with a waiting period of equivalent time. Membrane potentials of the US-treated and control groups differed significantly (Wilcoxon rank-sum test, *p = 1.55e-4) when the same Retzius cell was re-impaled. However, the US and control groups showed no significant (n.s.) difference (Wilcoxon rank-sum test, p = 0.1605) when the contralateral cell was recorded.