Ultrasound neuro-modulation chip: activation of sensory neurons in Caenorhabditis elegans by surface acoustic waves
Wei Zhou, Jingjing Wang, Kaiyue Wang, Bin Huang, Lili Niu, Fei Li, Feiyan Cai, Yan Chen, Xin Liu, Xiaoyan Zhang, Hankui Cheng, Lijun Kang, Long Meng, Hairong Zheng
Lab on a Chip 2017, 17, 1725-1731 · 10.1039/c7lc00163k
Abstract
Ultrasound neuro-modulation has gained increasing attention as a non-invasive method. In this paper, we present an ultrasound neuro-modulation chip, capable of initiating reversal behaviour and activating neurons of C. elegans under the stimulation of a single-shot, short-pulsed ultrasound. About 85.29% ± 6.17% of worms respond to the ultrasound stimulation exhibiting reversal behaviour. Furthermore, the worms can adapt to the ultrasound stimulation with a lower acoustic pulse duration of stimulation. In vivo calcium imaging shows that the activity of ASH, a polymodal sensory neuron in C. elegans, can be directly evoked by the ultrasound stimulation. On the other hand, AFD, a thermal sensitive neuron, cannot be activated by the ultrasound stimulation using the same parameter and the temperature elevation during the stimulation process is relatively small. Consistent with the calcium imaging results, the tax-4 mutants, which are insensitive to temperature increase, do not show a significant difference in avoidance probability compared to the wild type. Therefore, the mechanical effects induced by ultrasound are the main reason for neural and behavioural modulation of C. elegans. With the advantages of confined acoustic energy on the surface, compatible with standard calcium imaging, this neuro-modulation chip could be a powerful tool for revealing the molecular mechanisms of ultrasound neuro-modulation.
Abstract via europepmc.
Exposures
Exposure 1: SAW ultrasound stimulation of C. elegans on neuro-modulation chip
Target: c elegans neurons — “whole worm body / ASH and AFD sensory neurons of C. elegans on an agar surface”
Device: custom-built
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 28,110 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.0064, 0.00213swept | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | ⚑ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Worms on an agar surface mounted on interdigital transducers (IDTs) were stimulated with a single-shot radio-frequency ultrasound pulse (surface acoustic wave) of 6.40 ms duration and 5 W electric input power to elicit reversal behaviour and neuronal calcium responses; each worm received only a single stimulus for the main behavioural assay to avoid adaptation. In separate adaptation experiments, worms received repeated stimuli (up to 16 applications) at 10 s or 15 s intervals, with pulse duration reduced to as little as 2.13 ms; adaptation (declining response) was greater at the shorter pulse duration.
Consistency checks: f0 out of range.
Flags from extraction
n_subjects— The paper reports several different group sizes for distinct sub-experiments (e.g., n=34 for the main reversal assay, n=25/23/34 for stimulation-position tests, n=17 for ASH calcium imaging, n=13 for AFD imaging, n=25 for tax-4 mutants) but never a single total number of worms used; recorded as not_reported rather than summed or listed inconsistently.exposures[0].timing.sonication_duration_s— 6.40 ms and 2.13 ms pulse durations are explicitly stated in the main text; additional intermediate durations are shown only in Fig. 2(c) and are not extracted since figures alone do not count.exposures[0].free_field.isppa_w_cm2— The paper reports only electric input power to the transducer (~5 W) rather than an acoustic intensity or pressure at the worm; no ISPPA/ISPTA/pressure value could be extracted.anaesthesia— No anaesthetic protocol is described for C. elegans; 'awake' is inferred from the description of freely moving, behaviourally responsive worms rather than an explicit statement.