Ultrasound Neurostimulation in Mice: Impact of Ultrasound Settings and Beam Properties
Tarik Iazourene, Hanaa Malloul, Rasha M. Noureddine, Edward Oujagir, Jean-Michel Escoffre, Ayache Bouakaz
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2022 · 10.1109/tuffc.2022.3144335
Abstract
Ultrasound neurostimulation (USNS) is being investigated as a treatment approach for neuropsychiatric and neurodegenerative disorders. Indeed, unlike the existing methods that use electric or magnetic stimulation, it offers the possibility to modulate brain activity in a noninvasive way, with good spatial specificity and a high penetration capacity. However, there is no consensus yet on ultrasound parameters and beam properties required for efficient neurostimulation. In this context, this preclinical study aimed to elucidate the effect of frequency, peak negative pressure (PNP), pulse duration (PD), and focal spot diameter, on the USNS efficiency. This was done by targeting the motor cortex (M1) of 70 healthy mice and analyzing the elicited motor responses (visually and with electromyography). Also, a further investigation was performed by assessing the corresponding neuronal activity, using c-Fos immunostaining. The results showed that the success rate, a metric that depicts USNS efficacy, increased with PNP in a sigmoidal way, reaching up to 100%. This was verified at different frequencies (0.5, 1, 1.5, and 2.25 MHz) and PDs (53.3, 160, and 320 ms, at 1.5 MHz fixed frequency). Moreover, it was shown that higher PNP values were required to achieve a constant USNS efficacy not only when frequency increased, but also when the focal spot diameter decreased, emphasizing a close link between these acoustic parameters and USNS efficacy. These findings were confirmed with immunohistochemistry (IHC), which showed a strong relationship between neural activation, the applied PNP, and the focal spot diameter.
Abstract via europepmc.
Exposures
Exposure 1: 0.5 MHz motor cortex USNS
Target: primary motor cortex — “primary motor cortex (M1)”
Device: Sonic Concepts · Imasonic (France); Sonic Concepts (USA) ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.16 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | derating | |
| In-situ pressure (kPa) | 55, 550swept | ✓✓✓⚑ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Ten acoustic pulses (bursts) per parameter set separated by a burst interval of 10 s; pulse duration 160 ms.
Exposure 2: 1 MHz motor cortex USNS
Target: primary motor cortex — “primary motor cortex (M1)”
Device: custom-built · Laboratory made ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.16 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | derating | |
| In-situ pressure (kPa) | not reported | ⚑ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Ten acoustic pulses (bursts) per parameter set separated by a burst interval of 10 s; pulse duration 160 ms.
Exposure 3: 1.5 MHz motor cortex USNS
Target: primary motor cortex — “primary motor cortex (M1)”
Device: Sonic Concepts · Sonic Concepts, Bothell, WA, USA ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 1,500 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.0533, 0.16, 0.32swept | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | derating | |
| In-situ pressure (kPa) | not reported | ⚑ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Ten acoustic pulses (bursts) per parameter set separated by a burst interval of 10 s; pulse duration 160 ms (53.3, 160 and 320 ms tested at 1.5 MHz).
Exposure 4: 2.25 MHz motor cortex USNS
Target: primary motor cortex — “primary motor cortex (M1)”
Device: Olympus / Panametrics · Olympus NDT, Waltham, MA, USA ✓
| Waveform | continuous | |
|---|---|---|
| Fundamental frequency (kHz) | 2,250 | ✓✓✓ |
| Pulse duration (ms) | not applicable | |
| Pulse repetition frequency (Hz) | not applicable | |
| Duty cycle (%) | not applicable | |
| Sonication duration (s) | 0.16 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | derating | |
| In-situ pressure (kPa) | not reported | ⚑ |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
Ten acoustic pulses (bursts) per parameter set separated by a burst interval of 10 s; pulse duration 160 ms.
Flags from extraction
exposures[0].device.family— Two 0.5 MHz transducers were used (Imasonic and Sonic Concepts); a single family value cannot represent both.exposures[0].in_situ.pressure_kpa— 55-550 kPa is the PNP range used at 0.5 MHz for the focal-spot experiment; paper states PNPs were derated for the skull (12% at 0.5 MHz); in_situ placement inferred from that statement.exposures[1].in_situ.pressure_kpa— Paper gives only an overall PNP range of 55 to 1460 kPa (derated) across all frequencies, not split per frequency; left not_reported.exposures[2].in_situ.pressure_kpa— Paper gives only an overall PNP range of 55 to 1460 kPa (derated) across all frequencies, not split per frequency; left not_reported.exposures[3].in_situ.pressure_kpa— Paper gives only an overall PNP range of 55 to 1460 kPa (derated) across all frequencies, not split per frequency; left not_reported.exposures[1].device.manufacturer— 1 MHz transducer listed as 'Laboratory made'.exposures[1].timing.sonication_duration_s— Burst (pulse) of 160 ms is a single continuous tone burst per trial; paper uses 'pulse duration'; recorded as sonication duration with waveform continuous.exposures[2].timing.sonication_duration_s— 53.3 ms converted to 0.0533 s.exposures[0].timing.protocol_description— Frequency experiments split into four exposures because the transducer differed per frequency; sham group for c-Fos received identical conditions without USNS.