Low-Intensity Focused Ultrasound-Mediated Attenuation of Acute Seizure Activity Based on EEG Brain Functional Connectivity
Minjian Zhang, Bo Li, Xiaodong Lv, Sican Liu, Yafei Liu, Rongyu Tang, Yiran Lang, Qiang Huang, Jiping He
Brain Sciences 2021, 11, 711 · 10.3390/brainsci11060711
Abstract
(1) Background: Ultrasound has been used for noninvasive stimulation and is a promising technique for treating neurological diseases. Epilepsy is a common neurological disorder, that is attributed to uncontrollable abnormal neuronal hyperexcitability. Abnormal synchronized activities can be observed across multiple brain regions during a seizure. (2) Methods: we used low-intensity focused ultrasound (LIFU) to sonicate the brains of epileptic rats, analyzed the EEG functional brain network to explore the effect of LIFU on the epileptic brain network, and continued to explore the mechanism of ultrasound neuromodulation. LIFU was used in the hippocampus of epileptic rats in which a seizure was induced by kainic acid. (3) Results: By comparing the brain network characteristics before and after sonication, we found that LIFU significantly impacted the functional brain network, especially in the low-frequency band. The brain network connection strength across multiple brain regions significantly decreased after sonication compared to the connection strength in the control group. The brain network indicators (the path length, clustering coefficient, small-worldness, local efficiency and global efficiency) all changed significantly in the low-frequency. (4) Conclusions: These results revealed that LIFU could reduce the network connections of epilepsy circuits and change the structure of the brain network at the whole-brain level.
Abstract via europepmc.
Exposures
Exposure 1: LIFU to hippocampus in KA-induced seizure (Group 1) and non-epileptic (Group 3) rats
Target: hippocampus — “hippocampus”
Device: other named manufacturer · Goworld, Guangdong, China ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 0.3 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 1,500 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 45% | |
| Sonication duration (s) | not reported |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | simulationsingle value | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | 0.101 | ✓✓✓⚑ |
Kainic acid (6.5 mg/kg i.p.) was used to induce seizures in Group 1 (KA+/LIFU+, n=7) and Group 2 (KA+/LIFU-, n=7, no sonication, served as comparison control); Group 3 (KA-/LIFU+, n=7) received sonication without epilepsy induction. When seizures (forelimb clonus and tail-twitches) lasted 60 s, sonication was applied 5 times to the hippocampus (Stage 3); EEG was recorded continuously through baseline, pre-LIFU, sonication, and post-LIFU (60 s) stages. The waveform used np=200 pulses per burst.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Computed from stated cycles-per-pulse (c.p.p.=150) divided by fundamental frequency (0.5 MHz), a sanctioned unit conversion, not stated directly as a duration in ms.sham_type— Group 2 (KA+/LIFU-) received no transducer/apparatus at all as the comparison condition, rather than a classic inactive-transducer or active-control-site sham; coded as none.exposures[0].in_situ.ispta_w_cm2— Value comes from a finite-element simulation of the sound field in brain tissue; corresponding pressure and ISPPA values are only shown graphically (Figure 8) and not stated numerically in text.