Focused ultrasound stimulation of infralimbic cortex attenuates reinstatement of methamphetamine-induced conditioned place preference in rats
Chia-Wei Lin, Min-Hsuan Cheng, Ching-Hsiang Fan, Hwei-Hsien Chen, Chih-Kuang Yeh
Neurotherapeutics 2024, 21, e00328 · 10.1016/j.neurot.2024.e00328
Abstract
Methamphetamine (MA) use disorder poses significant challenges to both the affected individuals and society. Current non-drug therapies like transcranial direct-current stimulation and transcranial magnetic stimulation have limitations due to their invasive nature and limited reach to deeper brain areas. Transcranial focused ultrasound (FUS) is gaining attention as a noninvasive option with precise spatial targeting, able to affect deeper areas of the brain. This research focused on assessing the effectiveness of FUS in influencing the infralimbic cortex (IL) to prevent the recurrence of MA-seeking behavior, using the conditioned place preference (CPP) method in rats. The study involved twenty male Sprague-Dawley rats. Neuronal activation by FUS was first examined via electromyography (EMG). Rats received alternately with MA or saline, and confined to one of two distinctive compartments in a three compartment apparatus over a 4-day period. After CPP test, extinction, the first reinstatement, and extinction again, FUS was applied to IL prior to the second MA priming-induced reinstatement. Safety assessments were conducted through locomotor and histological function examinations. EMG data confirmed the effectiveness of FUS in activating neurons. Significant attenuation of reinstatement of MA CPP was found, along with successful targeting of the IL region, confirmed through acoustic field scanning, c-Fos immunohistochemistry, and Evans blue dye staining. No damage to brain tissue or impaired locomotor activity was observed. The results of the study indicate that applying FUS to the IL markedly reduced the recurrence of MA seeking behavior, without harming brain tissue or impairing motor skills. This suggests that FUS could be a promising method for treating MA use disorder, with the infralimbic cortex being an effective target for FUS in preventing MA relapse.
Abstract via europepmc.
Exposures
Exposure 1: EMG threshold-finding FUS stimulation of primary motor cortex
Target: primary motor cortex — “primary motor cortex”
Device: Olympus / Panametrics · Olympus · V318 ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 80 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 0.2 | ✓✓✓⚑ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 1.6% | |
| Sonication duration (s) | not reported |
| Free-field pressure (kPa) | 0, 400swept | ✓✓✓ |
|---|---|---|
| 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 |
Long tone bursts of 40,000 cycles were delivered with a pulse repetition interval of 5 s at acoustic pressures from 0 to 400 kPa; each experiment comprised 1 min of background EMG recording followed by 12 FUS stimulations, repeated once for a total of 4 min, with experiments run three times per pressure and a 10-min interval between trials.
Exposure 2: FUS stimulation of the infralimbic cortex (IL)
Target: ventromedial prefrontal cortex — “infralimbic cortex (IL)”
Device: Olympus / Panametrics · Olympus · V318 ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 500 | ✓✓✓ |
| Pulse duration (ms) | 0.16 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 500 | ✓✓✓⚑ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 8% | |
| Sonication duration (s) | 1,200 | ✓✓✓ |
| Free-field pressure (kPa) | 328 | ✓✓✓ |
|---|---|---|
| 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 |
For behavioural treatment (prior to the 2nd reinstatement test), H&E safety assessment, and c-Fos immunohistochemistry, FUS (80 cycles, PRI 2 ms) was delivered to IL for 20 min. For Evans-blue/microbubble confirmation of the FUS focal site, FUS (5000 cycles, PRI 1 s) was delivered for 60 s together with an IV bolus of Evans blue dye and microbubbles.
Flags from extraction
n_subjects— Abstract states 'twenty' male Sprague-Dawley rats while Methods states 'This study utilized 30 male Sprague-Dawley rats'; the more detailed Methods figure (30) is recorded here.exposures[0].unspecified_domain.pressure_kpa— Domain (free field vs in situ/brain) of the 0-400 kPa EMG-threshold pressure sweep is not stated; placed in unspecified_domain.exposures[1].unspecified_domain.pressure_kpa— Domain of the 328 kPa pressure applied to IL is not stated explicitly; the authors describe selecting it using a soft-tissue attenuation coefficient because IL is deeper than the M1 calibration site, but do not report it as a measured in-situ/derated value; placed in unspecified_domain.exposures[0].timing.pulse_duration_ms— Pulse duration (80 ms) converted from the stated 40,000 cycles at 0.5 MHz (cycles / frequency), a unit conversion.exposures[0].timing.pulse_repetition_frequency_hz— PRF (0.2 Hz) converted from the stated pulse repetition interval of 5 s, a unit conversion (1/period).exposures[1].timing.pulse_duration_ms— Pulse durations (0.16 ms and 10 ms) converted from stated cycle counts (80 and 5000 cycles) at 0.5 MHz, a unit conversion.exposures[1].timing.pulse_repetition_frequency_hz— PRF values (500 Hz and 1 Hz) converted from stated PRIs (2 ms and 1 s), a unit conversion (1/period).exposures[1].timing— Two different IL sonication protocols are reported: (a) 80 cycles/PRI 2 ms/20 min used for the behavioural treatment, H&E safety check and c-Fos IHC; (b) 5000 cycles/PRI 1 s/60 s used only for Evans-blue/microbubble confirmation of the FUS focal site (a distinct bioeffect involving co-administered microbubbles, not the neuromodulation treatment); both are listed as parameter pairs for the same target/frequency.sham_type— Control group underwent the same surgery/anaesthesia without FUS; no inactive-transducer or other defined sham device is described.