Mechanical artifacts during transcranial focused ultrasound mimic biologically evoked responses
Duc T Nguyen, Elisa E Konofagou, Jacek P Dmochowski
Brain Stimulation 2025 · 10.1016/j.brs.2025.05.114
rodenthealthyinvasive electrophysiology
Speciesrat
Subjectsnot reported animals
Sessions per subjectnot reported
Randomisednot reported
Blindingnot reported
Sham / controlinactive transducer, active control site
Auditory controlcontrol experiment
Readout timingonline
Anaesthesiaanaesthetised
Readoutsinvasive electrophysiology — 32-channel silicon microelectrode LFP and multi-unit activity; spatial PCA of LFP
Direction of effectmixed or uncleartFUS evoked a stereotyped LFP response time-locked to sonication onset and offset that was also present post mortem and absent with sham and olfactory bulb sonication; the authors conclude it is a mechanical electrode artifact rather than a neural effect.
Adverse eventsnot reported
Exposures
Exposure 1: tFUS to hippocampus (AM, CW, PW)
Target: hippocampus — “hippocampus”
Device: not reported
| Waveform | other_patterned, continuous, pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 2,500 | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | not reported | |
| Duty cycle (%) | not reported | |
| Sonication duration (s) | 1 | ✓✓✓ |
| 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 | |
| Ispta, domain unspecified (W/cm²) | 0.013, 3.3swept | ✓✓✓⚑ |
Protocol, in the paper’s words
1 s sonications spaced 5-10 s apart at five intensities and three waveforms (amplitude modulated, continuous wave, pulsed wave) to the anaesthetised rat hippocampus; also repeated post mortem; sham was a 1 cm air gap and an active control sonicated the contralateral olfactory bulb. Pulsed-wave and AM parameters are not given.
Flags from extraction
exposures[0].unspecified_domain.ispta_w_cm2— Range 13 mW/cm2 to 3.3 W/cm2 Ispta from text; Figure 1 legend gives the lowest of five intensities as 52 mW/cm2. Domain not stated.n_subjects— Number of animals not stated; n = 300 trials per condition only.exposures[0].timing— PRF, duty cycle and pulse duration of the pulsed-wave and AM conditions are not given.direction_of_effect— Study is about a recording artifact; the evoked response is attributed to electrode motion.exposures[0].device— Transducer maker not named; 2.5 MHz only.