Biology subjects

Bault, N.

Publications and source records attributed to Bault, N..

3 recordsLinked to original sources

bioRxiv2025

Multi-focal ultrasound neuromodulation to the dorsal anterior cingulate cortex disrupts behavioural and neural pain processing

Transcranial ultrasound stimulation (TUS) is a promising non-invasive technique for modulating deep brain regions involved in pain. TUS applied to the dorsal anterior cingulate cortex (dACC), a region implicated in chronic pain and established target for deep brain stimulation, has shown potential for reducing pain. This study aimed to investigate the neural mechanisms underlying TUS effects on pain in healthy participants using neuroimaging. Thirty-two participants underwent two double-blind, randomised TUS-fMRI sessions (active or sham). A tonic cold stimulus was applied during multifocal dACC-TUS and during fMRI and magnetic resonance spectroscopy (MRS) blocks. While no significant main effect of TUS on pain intensity was observed, active TUS showed a significantly greater reduction in pain ratings between 28- and 55-minutes post-stimulation, suggesting a delayed analgesic effect. Active TUS also disrupted the typical relationship between stimulus temperature and reported pain intensity, indicating altered sensory encoding. There was increased functional connectivity between the dACC and the supplementary motor area, pre-motor cortex, mid-ACC and the supramarginal gyrus, along with decreased coupling with the periaqueductal grey (PAG), and altered salience network connectivity. Overall, these findings suggest TUS to the dACC has multidimensional effects across behavioural and neural aspects of pain processing, supporting its potential therapeutic value.

neuroscience↗

bioRxiv2025

Ultrasound neuromodulation reveals distinct roles of the dorsal anterior cingulate cortex and anterior insula in Pavlovian biases

Pavlovian biases reflect the notorious influence of hard-wired, evolutionarily conserved cue-response tendencies on instrumental action selection: people show automatic action invigoration in face of potential rewards, but action suppression in face of potential punishments. The neural origin of these biases is unclear. Past evidence suggests dorsal anterior cingulate cortex (dACC) and anterior insula (aIns) as part of a "reset network" that rapidly responds to salient information and might contribute to these biases. We used transcranial ultrasonic stimulation (TUS) in 29 healthy participants to interfere with neural activity in these regions and test their causal role in a within-subject, counter-balanced design across three sessions (sham, TUS-dACC, TUS-aIns). Computational modelling revealed a double dissociation, with distinct roles of both regions in Pavlovian biases: while TUS to the aIns decreased peoples tendency to overly take credit for rewards following action and to ignore punishments following inaction, TUS to dACC increased participants tendency to take the cue valence as a reinforcer signal. Although the dACC and aIns are part of the same network and often co-activate during decision-making tasks, TUS interference reveals their distinct roles: the dACC mediates cue-dependence persistence while the aIns is critical for inferring whether outcomes are self-caused.

neuroscience↗

bioRxiv2024

Non-invasive Ultrasound Deep Neuromodulation of the Human Nucleus Accumbens Increases Win-Stay Behaviour

Precisely neuromodulating deep brain regions could bring transformative advancements in both neuroscience and treatment. We demonstrate that non-invasive transcranial ultrasound stimulation (TUS) can selectively modulate deep brain activity and affect learning and decision making, comparable to deep brain stimulation (DBS). We tested whether TUS could causally influence neural and behavioural responses by targeting the nucleus accumbens (NAcc) using a reinforcement learning task. Twenty-six healthy adults completed a within-subject TUS-fMRI experiment with three conditions: TUS to the NAcc, dorsal anterior cingulate cortex (dACC), or Sham. After TUS, participants performed a probabilistic learning task during fMRI. TUS-NAcc altered BOLD responses to reward signals in the NAcc and surrounding areas. It also affected reward-related features, including win-stay strategy use, learning rate following rewards and learning curves. DBS-NAcc perturbed the same features, confirming target engagement. These findings establish TUS as a viable approach for non-invasive deep-brain neuromodulation.

neuroscience↗