Behavioral and Functional Assessment of Ultrasound Neuromodulation on Caenorhabditis Elegans
Quanxiang Xian, Zhihai Qiu, Shashwati Kala, Kin Fung Wong, Jinghui Guo, Lei Sun
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2021 · 10.1109/tuffc.2021.3057873
Abstract
Ultrasound brain stimulation is a promising modality for probing brain function and treating brain diseases. However, its mechanism is as yet unclear, and in vivo effects are not well-understood. Here, we present a top-down strategy for assessing ultrasound bioeffects in vivo, using Caenorhabditis elegans. Behavioral and functional changes of single worms and of large populations upon ultrasound stimulation were studied. Worms were observed to significantly increase their average speed upon ultrasound stimulation, adapting to it upon continued treatment. Worms also generated more reversal turns when ultrasound was ON, and within a minute post-stimulation, they performed significantly more reversal and omega turns than prior to ultrasound. In addition, in vivo calcium imaging showed that the neural activity in the worms' heads and tails was increased significantly by ultrasound stimulation. In all, we conclude that ultrasound can directly activate the neurons of worms in vivo, in both of their major neuronal ganglia, and modify their behavior.
Abstract via europepmc.
Exposures
Exposure 1: LILFUS on freely moving worms
Target: c elegans neurons — “neurons in the worms’ heads and intestines”
Device: not reported
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | 0.2 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 20% | |
| Sonication duration (s) | not reported | ⚑ |
| 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) | 370 | ✓✓✓⚑ |
200 bursts of 1 MHz, 200 us pulsewidth, 1 kHz PRF with a 5 s interval, repeated over a 20 min stimulation for the speed assay; train length and number of bursts per stimulus are not unambiguously stated.
Flags from extraction
n_subjects— Only trial or group sizes are given (4 trials of 50 worms; n = 14; 7 and 3 worms; 29 worms for intestine); no total.exposures[0].unspecified_domain.pressure_kpa— 0.37 MPa spatial peak-temporal peak pressure; the paper says the field was characterised with a hydrophone but does not say the value is a free-field or water measurement.exposures[0].timing.sonication_duration_s— '200 bursts' with 1 kHz PRF could be the pulse train or the number of pulses; the burst meaning is ambiguous and no train duration is stated. Duty cycle not stated.exposures[0].device.family— Transducer maker not named ('ultrasound transducers with a center frequency of 1 MHz').blinding— The paper says the observer was not blind to the genotype of the group tested.