High‐Precision Photoacoustic Neural Modulation Uses a Non‐Thermal Mechanism
Guo Chen, Feiyuan Yu, Linli Shi, Carolyn Marar, Zhiyi Du, Danchen Jia, Ji‐Xin Cheng, Chen Yang
Advanced Science 2024 · 10.1002/advs.202403205
Abstract
Neuromodulation is a powerful tool for fundamental studies in neuroscience and potential treatments of neurological disorders. Both photoacoustic (PA) and photothermal (PT) effects are harnessed for non-genetic high-precision neural stimulation. Using a fiber-based device excitable by a nanosecond pulsed laser and a continuous wave laser for PA and PT stimulation, respectively, PA and PT neuromodulation is systematically investigated at the single neuron level. These results show that to achieve the same level of neuron activation recorded by Ca 2+ imaging, the laser energy needed for PA stimulation is 1/40 of that needed for PT stimulation. The threshold energy for PA stimulation is found to be further reduced in neurons overexpressing mechano-sensitive channels, indicating direct involvement of mechano-sensitive channels in PA stimulation. Electrophysiology study of single neurons upon PA and PT stimulation is performed by patch clamp recordings. Electrophysiological features induced by PA are distinct from those by PT, confirming that PA and PT stimulation operate through different mechanisms. These insights offer a foundation for the rational design of more efficient and safer non-genetic neural modulation approaches.
Abstract via europepmc.
Exposures
Exposure 1: Photoacoustic fiber emitter (candle soot/PDMS) driven by ns pulsed laser
Target: cultured neurons — “cultured cortical neurons”
Device: custom-built · Fiber emitter: 200 um optical fiber tip coated with candle soot and PDMS, driven by a 1030 nm 3 ns laser ✓
| Waveform | other patterned | |
|---|---|---|
| Fundamental frequency (kHz) | not reported | ⚑ |
| Pulse duration (ms) | not reported | ⚑ |
| Pulse repetition frequency (Hz) | 1,700, 4,230swept | ✓✓✓⚑ |
| Duty cycle (%) | not reported | |
| Sonication duration (s) | 0.0015, 0.003swept | ✓✓✓⚑ |
| Free-field pressure (kPa) | 8,000 | ✓✓✓⚑ |
|---|---|---|
| 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) | 5,000 | ✓✓✓⚑ |
Nanosecond laser pulses (3 ns, 1030 nm) at 4.23 kHz repetition rate for Ca imaging (1.7 kHz in the ion-channel experiments) delivered as 1.5 ms or 3 ms bursts, average laser power 120 mW, fiber tip about 50 um from the neurons. Photothermal comparison used a CW 1064 nm laser for 10 to 100 ms.
Flags from extraction
exposures[0].free_field.pressure_kpa— Peak-to-peak pressure 'over 8 MPa' at 45 uJ per pulse measured by hydrophone 50 um from the tip in water; recorded as 8000, lower bound only.exposures[0].unspecified_domain.pressure_kpa— 5 MPa is an estimate from laser pulse energy for the Ca imaging condition; domain not stated.exposures[0].timing.pulse_duration_ms— 3 ns laser pulse converted to ms.exposures[0].timing.pulse_repetition_frequency_hz— 4.23 kHz for Ca imaging and patch clamp; 1.7 kHz in the pharmacology and overexpression experiments.exposures[0].timing.sonication_duration_s— 1.5 ms and 3 ms bursts; recorded in seconds.exposures[0].fundamental_frequency_khz— Optoacoustic broadband emission; no carrier frequency stated in the text (spectrum shown in a figure only).exposures[0].device.family— Stimulus is laser-generated optoacoustic transients from a fiber emitter, not a conventional ultrasound transducer; scope doubtful (condition B).
Notes: Probable out of scope: optoacoustic transients generated by a pulsed laser at a fiber tip, with a CW-laser photothermal comparison.