Effect of noninvasive focused ultrasound stimulation on gamma oscillations in rat hippocampus
Yi Yuan, Jiaqing Yan, Zhitao Ma, Xiaoli Li
NeuroReport 2016 · 10.1097/wnr.0000000000000572
Abstract
In recent years, noninvasive focused ultrasound stimulation (FUS), with the advantage of high spatial resolution and high penetration depth, has developed rapidly for modulating neuron activities in the brain. Gamma oscillations serve to synchronize neurons and play important roles in cortical information processing and cognitive function. However, how FUS modulates gamma oscillations in the rat hippocampus is not well understood. In this work, we characterized the interactions between the gamma amplitude and phases of the delta, theta, and alpha bands during FUS. Our results show that FUS can significantly modulate the extent of phase-locked gamma amplitude and phase-amplitude coupling of brain oscillations. In summary, FUS can modulate gamma oscillations in the rat hippocampus, indicating its potential as a powerful noninvasive method to interfere with brain rhythms for diagnostic and therapeutic purposes.
Abstract via europepmc.
Exposures
Exposure 1: 2.5 MHz FUS to hippocampal CA1
Target: CA1 — “CA1 of the rat hippocampus”
Device: not reported · focused transducer driven by USB-UT350T transmitter card (US Ultratek)
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 2,500 | ✓✓✓ |
| Pulse duration (ms) | 0.0016 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 500 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 0.08% | ⚑ |
| 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 | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Isppa, domain unspecified (W/cm²) | 9.8 | ✓✓✓⚑ |
| Ispta, domain unspecified (W/cm²) | 0.00784 | ✓✓✓⚑ |
Pulses of four cycles at 500 Hz pulse repetition rate, each stimulus consisting of 80 ultrasound pulses; stimulation duration 160 ms and pulse duration 1.6 microseconds.
Flags from extraction
exposures[0].unspecified_domain.isppa_w_cm2— Intensity measured with an ultrasonic power measuring instrument; medium and whether skull in path not stated.exposures[0].unspecified_domain.ispta_w_cm2— Paper gives 7.84 mW/cm2; converted to W/cm2 as 0.00784 (unit conversion only).exposures[0].timing.pulse_duration_ms— Paper states 1.6 microseconds; recorded as 0.0016 ms.exposures[0].timing.duty_cycle_pct— Not stated; not computed.auditory_control— Authors compared LFP before and during ultrasound emission with the transducer moved relative to the brain, concluding transducer sound had no effect; treated as a control experiment.sham_type— Pre-FUS recording served as the control; no sham arm.direction_of_effect— Outcome is changes in gamma coupling, not clearly excitatory or inhibitory.