Integrating ultrasonic neuromodulation with fiber photometry
Aditya Vasan, Uri Magaram, Janki Patel, James Friend, Sreekanth H. Chalasani
Frontiers in Acoustics 2023 · 10.3389/facou.2023.1326759
Abstract
Ultrasound has been used to modulate neural activity in rodents and primates; however, combining ultrasound stimulation with in vivo imaging in freely moving animals has been challenging. Here, we design and validate a transducer to overcome these challenges in the rodent. We develop a head-mounted ultrasound transducer that can be combined with a fiber photometry system. This combination allows us to monitor ultrasound-evoked responses in striatal neurons in awake and freely moving animals. Together, this system allows for a high-resolution analysis of ultrasound-evoked biology at the level of both neural circuits and behavior in freely moving animals, critical to providing a mechanistic understanding of ultrasound neuromodulation.
Abstract via crossref.
Exposures
Exposure 1: head-mounted 6.56 MHz transducer, dorsal striatum
Target: dorsal striatum — “dorsal striatum”
Device: custom-built · custom single-crystal lithium niobate transducer (128YX cut), 5 x 5 mm, 500 um thick
| Waveform | not reported | |
|---|---|---|
| Fundamental frequency (kHz) | 6,560 | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | not reported | |
| Duty cycle (%) | not reported | |
| 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 | measurementmean or range across subjects | |
| In-situ pressure (kPa) | 300, 500swept | ✓✓✓⚑ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Pulse timing, PRF, duty cycle and stimulus duration are not stated. Ultrasound ON trials were interspersed with control pulses run at zero amplifier gain; the response was quantified in the 3-s window after stimulus delivery.
Flags from extraction
exposures[0].in_situ.pressure_kpa— 0.3-0.5 MPa peak negative pressure was measured through the intact skull in an ex vivo head preparation (fiber optic hydrophone in striatum) at varying input powers; not clear which level was used in the photometry trials.exposures[0].timing.waveform— Paper gives no pulse timing at all.auditory_control— Paper argues 6.56 MHz is outside the mouse hearing range; no control experiment, so recorded as 'other'.n_subjects— N = 5 for photometry; other numbers (6, 5-6) refer to rotarod and open-field tests without ultrasound output.readouts— Fiber photometry does not fit a listed readout; recorded as other.exposures[0].device.family— Transducer fabricated in-house (authors' own lithium niobate element).