A Multielectrode Array-Based Recording System for Analyzing Ultrasound-Driven Neural Responses in Brain Slices in vitro
Ryo Furukawa, Hiroki Kaneta, Takashi Tateno
Frontiers in Neuroscience 2022 · 10.3389/fnins.2022.824142
Abstract
Ultrasound stimulation is expected to be useful for transcranial local and deep stimulation of the brain, which is difficult to achieve using conventional electromagnetic stimulation methods. Previous ultrasound stimulation experiments have used various types of acute in vitro preparations, including hippocampus slices from rodents and Caenorhabditis elegans tissue. For in vivo preparations, researchers have used the cortices of rodents as targets for transcranial ultrasound stimulation. However, no previous studies have used in vitro ultrasound stimulation in rodent cortical slices to examine the mechanisms of ultrasound-driven central neural circuits. Here we demonstrate the optimal experimental conditions for an in vitro ultrasound stimulation system for measuring activity in brain slices using a multielectrode array substrate. We found that the peak amplitudes of the ultrasound-evoked cortical responses in the brain slices depend on the intensities and durations of the ultrasound stimulation parameters. Thus, our findings provide a new in vitro experimental setup that enables activation of a brain slice via ultrasound stimulation. Accordingly, our results indicate that choosing the appropriate ultrasound waveguide structure and stimulation parameters is important for producing the desired intensity distribution in a localized area within a brain slice. We expect that this experimental setup will facilitate future exploration of the mechanisms of ultrasound-driven neural activity.
Abstract via europepmc.
Exposures
Exposure 1: CW ultrasound to mouse auditory cortex slice via waveguide
Target: brain slice, auditory cortex — “brain slices that included the auditory cortex”
Device: Olympus / Panametrics · Olympus · V301-SU ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.1, 0.2swept | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not applicable | |
| In-situ pressure (kPa) | not applicable | |
| In-situ Isppa (W/cm²) | not applicable | |
| In-situ Ispta (W/cm²) | not applicable | |
| Pressure, domain unspecified (kPa) | 110, 210, 310, 410swept | ✓✓✓⚑ |
| Isppa, domain unspecified (W/cm²) | 0.41, 1.49, 3.24, 5.68swept | ✓✓✓⚑ |
Continuous-wave 500 kHz stimulus of 100 or 200 ms at four pressures (110-410 kPa), delivered through a 3D-printed waveguide below the MEA. Each stimulation block consisted of 20 trials with a 5 s interval, alternating with current stimulation blocks.
Flags from extraction
n_subjects— Seven slices from five mice; n_subjects is the number of slices (preparations).exposures[0].unspecified_domain.pressure_kpa— Pressures given as the stimulation pressure setting; the dish/bath has no skull; domain not stated so recorded as unspecified. Simulation text also uses 100 kPa at the transducer surface.exposures[0].unspecified_domain.isppa_w_cm2— Intensities 0.41, 1.49, 3.24 and 5.68 W/cm2 are stated to correspond to the four pressures (Isppa from Eq. 5).exposures[0].timing.protocol_description— Continuous-wave tone of 100 or 200 ms, with blocks of 20 trials at 5 s intervals; the paper calls it a CW with a fixed window length.