Non-invasive measurement of hemodynamic change during 8 MHz transcranial focused ultrasound stimulation using near-infrared spectroscopy
Evgenii Kim, Eloise Anguluan, Sangyeon Youn, Jihun Kim, Jae Youn Hwang, Jae Gwan Kim
BMC Neuroscience 2019 · 10.1186/s12868-019-0493-9
Abstract
Background Transcranial focused ultrasound (tFUS) attracts wide attention in neuroscience as an effective noninvasive approach to modulate brain circuits. In spite of this, the effects of tFUS on the brain is still unclear, and further investigation is needed. The present study proposes to use near-infrared spectroscopy (NIRS) to observe cerebral hemodynamic change caused by tFUS in a noninvasive manner. Results The results show a transient increase of oxyhemoglobin and decrease of deoxyhemoglobin concentration in the mouse model induced by ultrasound stimulation of the somatosensory cortex with a frequency of 8 MHz but not in sham. In addition, the amplitude of hemodynamics change can be related to the peak intensity of the acoustic wave. Conclusion High frequency 8 MHz ultrasound was shown to induce hemodynamic changes measured using NIRS through the intact mouse head. The implementation of NIRS offers the possibility of investigating brain response noninvasively for different tFUS parameters through cerebral hemodynamic change.
Abstract via europepmc.
Exposures
Exposure 1: 8 MHz tFUS of somatosensory cortex, two intensities
Target: somatosensory cortex — “somatosensory cortex”
Device: not reported
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 8,000 | ✓✓✓ |
| Pulse duration (ms) | 0.0625 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 1,500 | ✓✓✓ |
| Duty cycle (%) | 9pulse duration × PRF gives 9.375% | ✓✓✓ |
| Sonication duration (s) | 5 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | 0.468, 1.08swept | ✓✓✓⚑ |
| In-situ estimate | measurementsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | 0.056, 0.129swept | ✓✓✓⚑ |
Each trial: 5 s stimulation of ten pulse trains at 2 Hz, each train of 300 pulses of 500 cycles at 8 MHz with PRF 1500 Hz; trial 17 s, one trial per minute, 25 trials per condition (two intensities plus sham), randomly shuffled.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Pulse is 500 cycles at 8 MHz (Fig. 1 legend) but no duration in ms is stated.exposures[0].in_situ.ispta_w_cm2— Skull-transmitted Ispta of 129 and 56 mW/cm2 given in the discussion; paper reports 12% transmitted power through an excised skull, so values may derive from that measurement.exposures[0].timing.sonication_duration_s— Nested structure: 5 s stimulation of ten trains at 2 Hz, each 300 pulses at 1500 Hz.anaesthesia— Animals were isoflurane-anaesthetised for fixation then given at least 30 min to recover before acquisition; recorded as awake.exposures[0].free_field.ispta_w_cm2— Values for the two active conditions (468 and 1077 mW/cm2) recorded as a list.