Changes in theta and gamma oscillations of the medial prefrontal cortex following hippocampal-focused ultrasound stimulation
Jiwon Baek, Younghee Seo, Bong Soo Kim, Young Cheol Na, Won Seok Chang
Neurofunction 2024 · 10.52662/nf.2023.00094
Abstract
Objective: Neuromodulation is a rapidly growing field of treatment, encompassing implantable and noninvasive technology-based approaches. Focused ultrasound (FUS), a noninvasive method, has the potential to modulate neural activity in deep brain regions with spatial precision based on the penetrance of sound waves into the bone and soft tissue. However, neuromodulation is limited by the inability to confirm modulation in real-time. Electrophysiological technology is required to overcome this limitation. In this study, we aimed to confirm neural activity using Neuropixel electrodes during FUS sonication.Methods: Six male C57BL/6 mice were subjected to ultrasound sonication in the hippocampus. Simultaneously, local field potential (LFP) measurements were performed using Neuropixel electrodes. The experimental groups were divided into three categories: before, during, and after FUS sonication and the measured LFP data were compared between groups.Results: Theta and gamma waves were extracted from the recorded LFP data and compared between the groups. The theta and gamma oscillations changed after FUS sonication compared to before. The theta graph showed significant changes between the pre- and during-treatment groups and between the during- and post-treatment groups (theta: 4–8 Hz, F=23.91, p<0.0001). However, the gamma graph did not show significant changes in any groups (gamma: 30–50 Hz). Additionally, the expression of c-fos, a marker of neuronal activity, increased after FUS sonication.Conclusion: Although further research is needed—including longer follow-up LFP measurements after FUS sonication and the collection of more LFP data—neuromodulation with FUS can be considered usable in other neurological disease models.
Abstract via crossref.
Exposures
Exposure 1: Hippocampal FUS with mPFC LFP recording
Target: hippocampus — “right dorsal hippocampus”
Device: Sonic Concepts · Sonic Concept Inc. · H-107MR ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 515 | ✓✓✓ |
| Pulse duration (ms) | 0.2 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 1,000 | ✓✓✓ |
| Duty cycle (%) | 50pulse duration × PRF gives 20%, which disagrees with the stated value | ✓✓✓ |
| Sonication duration (s) | 0.3 | ✓✓✓ |
| 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 |
FUS parameters were 515 kHz fundamental frequency, 50% duty cycle, 1 kHz PRF, 0.2 ms tone-burst duration (TBD), 300 ms sonication duration, and 2 s inter-stimulus interval. LFP was measured 10 minutes before, 10 minutes during, and 10 minutes after FUS modulation in each group.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Stated duty cycle (50%) and PRF (1 kHz) imply a 0.5 ms pulse duration, but the paper states TBD = 0.2 ms (20% duty cycle at that PRF); values are recorded as stated without correction.sham_type— A 'control group (without FUS modulation)' is mentioned but the mechanism (e.g., transducer present/absent, powered off) is not described.n_subjects— Abstract/methods state 6 mice were sonicated, but the methods also describe 4 groups of 3 mice (control + pre/during/post-treatment), which is not fully reconcilable with n=6; recorded as explicitly stated in the abstract/methods opening sentence.