Low-intensity transcranial focused ultrasound engages parvalbumin-positive GABAergic interneurons in a humanized mouse model of chronic pain: from electrophysiology to cellular investigation.

Abstract

Low-intensity transcranial focused ultrasound (tFUS) offers high spatial specificity and deep brain penetration, representing a promising non-invasive approach for modulating brain activity and behavior. Although emerging studies indicate that tFUS can modulate pain-related behaviors in rodents and humans, the underlying network-level and cellular mechanisms remain unknown. This study investigates the effects of tFUS neuromodulation on inhibitory neural circuits in a humanized mouse model of chronic pain, integrating electrophysiological, molecular, and histological analyses across a cohort of 50 animals, including wild-type controls.A 128-element random array transducer was used to precisely target the pain-processing brain circuit, while a non-invasive and flexible 30-channel electroencephalography electrode was applied to record local evoked responses, topographical activity, and global excitation and inhibition dynamics, which were further validated by optogenetics experiments. Cellular-level modulation and safety outcomes were evaluated through blinded histological examination.We found that tFUS produced robust modulation of local and global brain activity, characterized by suppression of local theta oscillations and enhancement of network-level inhibitory dynamics. These electrophysiological patterns aligned with those observed during optogenetic activation of parvalbumin (PV) interneurons. Immunohistochemistry further showed significant increases in inhibitory neuronal markers, including elevated expressions of glutamate decarboxylase 67 and PV. Blinded histological assessment confirmed the absence of tissue damage, supporting the safety of the stimulation paradigm.These findings demonstrated that tFUS stimulation non-invasively engages PV GABAergic inhibitory circuits in a chronic pain mouse model, providing mechanistic insight and supporting its development as a precise and safe neuromodulation technology for clinical translation.