Neuromodulation of sensory networks in monkey brain by focused ultrasound with MRI guidance and detection
Pai-Feng Yang, M. Anthony Phipps, Allen T. Newton, Vandiver Chaplin, John C. Gore, Charles F. Caskey, Li Min Chen
Scientific Reports 2018, 8 · 10.1038/s41598-018-26287-7
Abstract
Focused ultrasound (FUS) has gained recognition as a technique for non-invasive neuromodulation with high spatial precision and the ability to both excite and inhibit neural activity. Here we demonstrate that MRI-guided FUS is capable of exciting precise targets within areas 3a/3b in the monkey brain, causing downstream activations in off-target somatosensory and associated brain regions which are simultaneously detected by functional MRI. The similarity between natural tactile stimulation-and FUS- evoked fMRI activation patterns suggests that FUS likely can excite populations of neurons and produce associated spiking activities that may be subsequently transmitted to other functionally related touch regions. The across-region differences in fMRI signal changes relative to area 3a/3b between tactile and FUS conditions also indicate that FUS modulated the tactile network differently. The significantly faster rising (>1 sec) fMRI signals elicited by direct FUS stimulation at the targeted cortical region suggest that a different neural hemodynamic coupling mechanism may be involved in generating fMRI signals. This is the first demonstration of imaging neural excitation effects of FUS with BOLD fMRI on a specific functional circuit in non-human primates.
Abstract via europepmc.
Exposures
Exposure 1: FUS to areas 3a/3b (S1) targeted via prior tactile fMRI mapping
Target: primary somatosensory cortex — “areas 3a/3b, primary somatosensory cortex (S1)”
Device: Sonic Concepts · Sonic Concepts · H115 ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 250 | ✓✓✓ |
| Pulse duration (ms) | 0.252 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 2,000 | ✓✓✓ |
| Duty cycle (%) | 50pulse duration × PRF gives 50.4% | ✓✓✓ |
| Sonication duration (s) | 0.3 | ✓✓✓ |
| Free-field pressure (kPa) | 935 | ✓✓✓ |
|---|---|---|
| Free-field Isppa (W/cm²) | 29.5 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 1.34 | ✓✓✓ |
| In-situ estimate | deratingsingle value | |
| In-situ pressure (kPa) | 543 | ✓✓✓ |
| In-situ Isppa (W/cm²) | 9.9 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.452 | ✓✓✓ |
FUS pulses were delivered in a block-based scheme identical to the tactile stimuli, in seven 30 sec FUS on/off cycles. During an “on” block, a 250 kHz, 300 msec pulse was emitted at 0.333 Hz (i.e. one 300 ms pulse every 3 s), with the procedure resulting in 10 FUS bursts per “on” block; each 300 msec pulse itself consisted of 63-cycle bursts repeated at 2 kHz (50% duty cycle).
Flags from extraction
exposures[0].timing.pulse_duration_ms— Not stated directly in ms; computed from '63-cycle bursts' at the 250 kHz fundamental frequency (63/250 kHz = 0.252 ms), consistent with the stated 2 kHz PRF and 50% duty cycle (0.5/2000 Hz = 0.25 ms).exposures[0].timing.protocol_description— The paper calls the 300 ms train a 'pulse' and its 63-cycle sub-elements 'bursts', the reverse of this archive's usual burst/pulse terminology; recorded per the paper's own wording.auditory_control— Paper does not discuss auditory confounds or controls for the audible click of FUS pulsing.