Biology subjects

Atkinson-Clement, C.

Publications and source records attributed to Atkinson-Clement, C..

6 recordsLinked to original sources

bioRxiv2025

Disrupting action control with transcranial ultrasound neuromodulation: a step forward for Tourette syndrome

BackgroundWhile Tourette syndrome (TS) is characterised by the presence of tics, premonitory urges are involved in both triggering them and as a lever to control them. The right insular cortex is known to play a key role in these processes, yet its precise functional contribution remains unclear. Transcranial ultrasound stimulation (TUS) is currently one of the only non-invasive neuromodulation techniques capable of safely and precisely modulating the activity of deep brain structures such as the insula. ObjectiveThis study used TUS to causally investigate the respective roles of the anterior and posterior insula in urge and action control during a blink suppression task. MethodsTwenty healthy adults underwent three TUS sessions targeting the right anterior insula, posterior insula, and posterior ventricle (control site) in a within-subject, crossover design. Behavioural outcomes included blink counts and urge ratings. Additionally, voxel-based correlations were conducted to further estimate the role of each reached area with acoustic stimulation, allowing for a better mechanical understanding. ResultsTUS of the anterior insula induced a clear and acute increase in blink frequency without altering urge, reinforced by voxel-based analyses, confirming its role in voluntary action control. Posterior insula stimulation induced delayed increases in both blinks and urge, which are essentially explained by an involuntary stimulation of the right inferior frontal gyrus. Ventricular stimulation unexpectedly reduced blink frequency during the stimulation only, correlated with acoustic energy delivered within the posterior internal capsule. No significant side effects or temperature rises were observed. ConclusionsThese findings provide the first causal evidence that TUS can modulate the two main features of TS: premonitory urge and action control. Distinct effects across targets highlight the anterior insulas critical role in action control and suggest the internal capsule as a potential therapeutic target for TS.

neuroscience↗

bioRxiv2025

Transcranial focused ultrasound stimulation of the anterior temporal lobe enhances semantic memory by modulating brain morphology, neurochemistry and neural dynamics

AbstractsUnderstanding neural functioning and plasticity of the brain is a fundamental goal of neuroscience. The ventromedial anterior temporal lobe (ATL) has been suggested as the centre-point of a core transmodal hub for semantic memory, playing a crucial role in the representation of coherent conceptual knowledge. However, non-invasive direct modulation of the ventromedial ATL has remained challenging. Transcranial ultrasound stimulation (TUS) is an emerging neuromodulatory technique that delivers acoustic energy with high spatial precision, making it uniquely suited for targeting deep brain structures non-invasively. In this study, we investigated whether theta-burst TUS (tbTUS) to the ventromedial ATL could enhance semantic memory performance in the adult brain. Using a multimodal neuroimaging approach-- magnetic resonance spectroscopy (MRS), functional MRI (fMRI), and voxel-based morphometry (VBM)--we assessed tbTUS-induced changes in neurochemical concentrations, functional network connectivity, structural plasticity, and semantic memory performance. Compared to control stimulation (ventricle), tbTUS at the ventromedial ATL significantly improved semantic task performance in healthy individuals. MRS analysis revealed that tbTUS decreased GABA and increased Glx levels, reflecting shifts in excitation-inhibition balance. Additionally, tbTUS increased neurometabolites in the ATL, including NAA, creatine and choline, suggesting enhanced neuronal function and metabolism. fMRI analysis demonstrated that tbTUS reduced task-induced regional activity in the ATL and functionally connected semantic regions, while also enhancing intrinsic and effective connectivity across the semantic network. Structural analysis revealed increased grey matter volume in the ATL following tbTUS compared to control stimulation. These findings provide the first convergent evidence that tbTUS can modulate neurochemistry, functional dynamics, and brain morphology to enhance semantic memory function. Our results highlight TUS as a powerful neuromodulatory tool with potential applications in cognitive enhancement and neurorehabilitation, offering a promising intervention for dementia and neurodegenerative disorders.

neuroscience↗

bioRxiv2025

Understanding the high-order network plasticity mechanisms of ultrasound neuromodulation

Transcranial ultrasound stimulation (TUS) is an emerging non-invasive neuromodulation technique, offering a potential alternative to pharmacological treatments for psychiatric and neurological disorders. While functional analysis has been instrumental in characterizing TUS effects, understanding the underlying mechanisms remains a challenge. Here, we developed a whole-brain model to represent functional changes as measured by fMRI, enabling us to investigate how TUS-induced effects propagate throughout the brain with increasing stimulus intensity. We implemented two mechanisms: one based on anatomical distance and another on broadcasting dynamics, to explore plasticity-driven changes in specific brain regions. Finally, we highlighted the role of higher-order functional interactions in localizing spatial effects of off-line TUS at two target areas--the right thalamus and inferior frontal cortex--revealing distinct patterns of functional reorganization. This work lays the foundation for mechanistic insights and predictive models of TUS, advancing its potential clinical applications. Significance StatementTranscranial ultrasound stimulation (TUS) offers a non-invasive approach to modulating brain activity, holding promise for treating psychiatric and neurological disorders. Despite its potential, the mechanisms underlying its effects remain poorly understood. By integrating human fMRI data with whole-brain computational models, we identified how high-order functional interactions localize and propagate TUS-induced effects from local to global brain scales. This work introduces two mechanisms--distance-based propagation and diffusion-like broadcasting--that predict functional plasticity changes, providing a foundation for understanding and optimizing the biological and cognitive outcomes of TUS. Our findings offer critical insights into the dynamics of neuromodulation, bridging experimental results and clinical applications.

neuroscience↗

bioRxiv2024

Ventricle stimulation as a potential gold-standard control stimulation site for transcranial focused ultrasound stimulation

This research investigates whether ventricular-focused ultrasound stimulation (ventricle-FUS) can serve as an effective control in studies using transcranial FUS, a non-invasive technology for brain modulation. FUS has notable potential for therapeutic applications but requires a robust control to accurately assess its effects. We evaluated the effectiveness of ventricle-FUS, as an active, non-cerebrum control for FUS research, comparing it to sham stimulation. We conducted a comprehensive assessment of ventricle-FUS, employing both questionnaires and multiple neuroimaging metrics such as grey matter and white matter volumes, and functional connectivity. Ventricle-FUS did not alter any of these metrics, thereby successfully retaining the auditory, somatosensory, and experiential elements of FUS without affecting brain structure or function. Importantly, participants were unable to distinguish whether they received ventricle-FUS or sham FUS. Our findings confirm that ventricle-FUS establishes it as a reliable control approach in FUS research, crucial for advancing its therapeutic applications.

neuroscience↗

bioRxiv2023

Transcranial ultrasound stimulation effect in the redundant and synergistic networks consistent across macaques

Low-intensity transcranial ultrasound stimulation (TUS) is a non-invasive technique that safely alters neural activity, reaching deep brain areas with good spatial accuracy. We investigated the effects of TUS at the level of macaque using a recent metric, the synergy minus redundancy rank gradient, that quantifies different kinds of causal neural information processing. We analyzed this high-order quantity on the fMRI data after TUS in two targets: the supplementary motor area (SMA-TUS) and the frontal polar cortex (FPC-TUS). The TUS produced specific changes at the limbic network at FPC-TUS and the motor network at SMA-TUS and altered, in both targets, the sensorimotor, temporal, and frontal networks, consistent across macaques. Moreover, there was a reduction in the structural and functional coupling after both stimulations. Finally, the TUS changed the intrinsic high-order network topology, decreasing the modular organization of the redundancy at SMA-TUS and increasing the synergistic integration at FPC-TUS.

neuroscience↗

bioRxiv2021

Action inhibition revisited: a new method identifiescompromised reactive but intact proactive control inTourette disorder

Tourette disorder (TD) is characterized by tics, which are sudden repetitive involuntary movements or vocalizations. Deficits in inhibitory control in TD patients remain inconclusive from the traditional method of estimating the ability to stop an impending action, which requires careful interpretation of a parameter derived from race model. One possible explanation for these inconsistencies is that race models assumptions are often violated. Here, we used a pair of metrics derived from a recent alternative model to address why stopping performance in TD patients is unaffected by impairments in neural circuitry. These new metrics distinguish between proactive and reactive inhibitory control and estimate them separately. When these metrics were contrasted with healthy controls (HC), we identified robust deficits in reactive control in TD patients, but not in proactive control. The patient population exhibited difficulty in slowing down the speed of movement planning, which they compensated by their intact ability of procrastination. TEASERTourette disorder patients inhibit action by means of strategic postponement to compensate impaired slowness in preparation.

neuroscience↗