Pulsed Focused Ultrasound Reduces Hippocampal Volume Loss and Improves Behavioral Performance in the Kainic Acid Rat Model of Epilepsy
Po-Chun Chu, Chen-Syuan Huang, Shan-Zhi Ing, Hsiang-Yu Yu, Robert S. Fisher, Hao-Li Liu
Neurotherapeutics 2023, 20, 502-517 · 10.1007/s13311-023-01363-7
Abstract
Focused ultrasound (FUS) has the potential to modulate regional brain excitability and possibly aid seizure control; however, effects on behavior of FUS used as a seizure therapy are unknown. This study explores behavioral effects and hippocampal restoration induced by pulsed FUS in a kainic acid (KA) animal model of temporal lobe epilepsy. Twenty-nine male Sprague-Dawley rats were observed for 20 weeks with anatomical magnetic resonance imaging (MRI) and behavioral performance evaluations, comprising measures of anxiety, limb usage, sociability, and memory. FUS targeted to the right hippocampus was given 9 and 14 weeks after KA was delivered to the right amygdala. Ultrasound pulsations were delivered with the acoustic settings of 0.25 of mechanical index, 0.5 W/cm 2 of intensity spatial peak temporal average (I SPTA ), 100 Hz of pulse repetition frequency, and 30% of duty cycle, during three consecutive pulse trains of 10 min separated by 5-min rests. Controls included normal animals with sham injections and KA-exposed animals without FUS exposure. Longitudinal MRI observations showed that FUS substantially protected hippocampal and striatal structures from KA-induced atrophy. KA alone increased anxiety, impaired contralateral limb usage, and reduced sociability and learning. Two courses of FUS sonications partially ameliorated these impairments by enhancing exploring and learning, balancing limb usage, and increasing social interaction. The histology results indicated that two sonications enhanced neuroprotection effect and decreased the inflammation markers induced by KA. This study supports existence of both neuroprotective and beneficial behavioral effects from low-intensity pulsed ultrasound in the KA animal model of epilepsy.
Abstract via europepmc.
Exposures
Exposure 1: Pulsed FUS to right hippocampus (KA epilepsy model)
Target: hippocampus — “right hippocampus”
Device: Sonic Concepts · Sonic Concepts
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | not reportedimplied by duty cycle ÷ PRF: 3 ms (not stated by the paper) | ⚑ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓ |
| Duty cycle (%) | 30 | ✓✓✓ |
| Sonication duration (s) | 600 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | measurementsingle value | |
| In-situ pressure (kPa) | 177 | ✓✓✓ |
| In-situ Isppa (W/cm²) | 1.67 | ✓✓✓ |
| In-situ Ispta (W/cm²) | 0.5 | ✓✓✓ |
Each FUS session consisted of three consecutive 10-min 'on' periods segmented by 5-min intermittent 'off' periods, delivered at week 9 and again at week 14 after kainic acid injection to the right amygdala (two courses of FUS in total).
Flags from extraction
n_subjects— MRI sub-cohort for the KA+FUS group is reported separately (4/4/4 scans at three timepoints) and may be a subset of, or overlap partially with, the n=6 behaviourally-tested KA+FUS animals; the paper does not fully reconcile the two cohorts.exposures[0].timing.pulse_duration_ms— Individual pulse duration is not stated in the text; only PRF (100 Hz) and duty cycle (30%) are given, and computing pulse duration from these would be arithmetic rather than a stated value.