Transcranial Low-Intensity Focused Ultrasound Stimulation of the Visual Thalamus Produces Long-Term Depression of Thalamocortical Synapses in the Adult Visual Cortex
Lukas Mesik, Samuel Parkins, Daniel Severin, Bryce D. Grier, Gabrielle Ewall, Sumasri Kotha, Christian Wesselborg, Cristian Moreno, Yanis Jaoui, Adrianna Felder, Brian Huang, Marina B. Johnson, Timothy P. Harrigan, Anna E. Knight, Shane W. Lani, Théo Lemaire, Alfredo Kirkwood, Grace M. Hwang, Hey-Kyoung Lee
The Journal of Neuroscience 2024, 44, e0784232024 · 10.1523/jneurosci.0784-23.2024
Abstract
Transcranial focused ultrasound stimulation (tFUS) is a noninvasive neuromodulation technique, which can penetrate deeper and modulate neural activity with a greater spatial resolution (on the order of millimeters) than currently available noninvasive brain stimulation methods, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). While there are several studies demonstrating the ability of tFUS to modulate neuronal activity, it is unclear whether it can be used for producing long-term plasticity as needed to modify circuit function, especially in adult brain circuits with limited plasticity such as the thalamocortical synapses. Here we demonstrate that transcranial low-intensity focused ultrasound (LIFU) stimulation of the visual thalamus (dorsal lateral geniculate nucleus, dLGN), a deep brain structure, leads to NMDA receptor (NMDAR)-dependent long-term depression of its synaptic transmission onto layer 4 neurons in the primary visual cortex (V1) of adult mice of both sexes. This change is not accompanied by large increases in neuronal activity, as visualized using the cFos Targeted Recombination in Active Populations (cFosTRAP2) mouse line, or activation of microglia, which was assessed with IBA-1 staining. Using a model (SONIC) based on the neuronal intramembrane cavitation excitation (NICE) theory of ultrasound neuromodulation, we find that the predicted activity pattern of dLGN neurons upon sonication is state-dependent with a range of activity that falls within the parameter space conducive for inducing long-term synaptic depression. Our results suggest that noninvasive transcranial LIFU stimulation has a potential for recovering long-term plasticity of thalamocortical synapses in the postcritical period adult brain.
Abstract via europepmc.
Exposures
Exposure 1: LIFU stimulation of dorsal lateral geniculate nucleus (dLGN)
Target: lateral geniculate nucleus — “visual thalamus (dorsal lateral geniculate nucleus, dLGN)”
Device: other named manufacturer · Benthowave Instruments Inc. · BII-7651H/500IMTS ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 590 | ✓✓✓ |
| Pulse duration (ms) | 0.0847 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 500 | ✓✓✓ |
| Duty cycle (%) | 4.24pulse duration × PRF gives 4.235% | ✓✓✓ |
| Sonication duration (s) | 3,600 | ✓✓✓ |
| Free-field pressure (kPa) | 270 | ✓✓✓ |
|---|---|---|
| Free-field Isppa (W/cm²) | 2.4 | ✓✓✓ |
| Free-field Ispta (W/cm²) | 0.099, 0.11swept | ✓✓✓ |
| 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 |
The first function generator set the pulse repetition frequency of 500 Hz and triggered the second function generator to send a tone burst of 50 pulses or a tone burst duration of 0.0847 msec. Each mouse was subjected to unilateral LIFU stimulation targeting left or right dLGN using these parameters for a total duration of 1 h under isoflurane anesthesia. For a group of mice, the NMDAR antagonist D-CPP (10 mg/kg, i.p.) was injected 10-20 min prior to the LIFU stimulation to test the role of NMDARs.
Flags from extraction
n_subjects— Paper reports separate group sizes for distinct sub-experiments (4 mice for LTD electrophysiology, 4 mice for the CPP/NMDAR-block experiment, 5 mice for cFosTRAP2/IBA-1 histology) without stating a combined total; values listed rather than summed.exposures[0].device.model— Design frequency of the transducer is stated as 0.5 MHz, but acceptance testing showed 0.59 MHz gave optimal power efficiency and was used for all procedures; both values appear in the text.