Summary: Researchers have demonstrated that non-invasive transcranial ultrasound stimulation (TUS) can alter human reward learning by targeting the nucleus accumbens, a deep brain region central to motivation. After brief, focused stimulation, participants learned more quickly from positive feedback and showed a greater tendency to repeat choices that had previously been rewarded.
These changes resemble important aspects of outcomes seen with surgical deep brain stimulation (DBS) but were achieved without implants or incisions. The findings raise the possibility that targeted ultrasound could become a safer, personalized approach for adjusting disrupted reward circuits in psychiatric and neurological disorders.
Key Facts
- Deep brain targeting: Focused ultrasound successfully modulated activity within the nucleus accumbens without surgical intervention.
- Improved reward learning: Participants were more sensitive to positive outcomes and adopted win-stay strategies more often after stimulation.
- Therapeutic potential: The technique shows promise as a non-invasive tool that could one day support treatments for addiction, depression, eating disorders and related conditions.
Source: University of Plymouth
About the nucleus accumbens: The nucleus accumbens is a small but crucial component of the brain’s reward circuitry. It integrates dopamine signals and emotional inputs to guide choices by strengthening behaviors that lead to rewarding outcomes.
In this study, researchers applied brief TUS sessions—just over a minute at a time—directed precisely at the nucleus accumbens. Following stimulation, participants completed learning and decision-making tasks while undergoing brain imaging. The intervention increased the speed and consistency with which participants learned from positive feedback and led them to repeat previously rewarded choices more reliably and often more quickly.
Until now, comparable changes in reward learning and motivation have mainly been induced through invasive procedures like deep brain stimulation, which requires implanting electrodes into the brain. By contrast, TUS offers a non-invasive route to engage the same deep structure, suggesting an alternative that avoids the risks and recovery associated with surgery.
The research, published in Nature Communications, was led by the University of Plymouth with contributions from the University of Oxford, John Radcliffe Hospital, University Hospitals Plymouth NHS Trust, Brown University, and the VA Providence Healthcare System. Professor Elsa Fouragnan, Director of the Centre for Therapeutic Ultrasound and the Brain Research and Imaging Centre (BRIC) at the University of Plymouth, led the project.
Professor Fouragnan commented that the nucleus accumbens has long been central to theories of motivation and reinforcement learning. She emphasized that demonstrating personalized, non-invasive modulation of this deep structure opens significant possibilities for translating neuromodulation into clinical practice.
The study is part of broader investigations at the University of Plymouth into the clinical potential of TUS for conditions such as anxiety, depression, addiction, and other psychiatric or neurological disorders. For this experiment, 26 healthy volunteers attended four sessions at the BRIC facility: an initial planning visit followed by three separate TUS sessions targeting different brain regions or a sham condition.
Approximately ten minutes after each TUS session, participants performed probabilistic reinforcement learning tasks inside an fMRI scanner for about an hour. The research team measured both behavioural changes and brain activity, comparing results across stimulation sites and against a clinical reference group of patients who had bilateral DBS electrodes implanted in the nucleus accumbens as part of treatment for severe, treatment-resistant anorexia nervosa.
The findings showed that TUS aimed at the nucleus accumbens altered BOLD responses related to reward expectation in the targeted region and nearby structures. Behaviourally, TUS increased the likelihood of using a win–stay strategy, raised the learning rate following rewards, and changed learning curves and repetition rates of rewarded choices. While DBS often normalizes certain aspects of reward-seeking, the study observed that TUS produced an excitatory effect on some measures; nonetheless, both interventions clearly engaged the same reward-related features.
Key Questions Answered
Q: Which brain region did researchers influence with ultrasound?
A: The nucleus accumbens, a deep reward center that helps steer motivation and learning.
Q: What behavioural changes followed stimulation?
A: Participants learned faster from positive outcomes, adopted win–stay strategies more often, and repeated previously rewarding choices more reliably.
Q: How does this compare to earlier methods?
A: Similar effects have previously required invasive brain surgery, whereas this study demonstrates a non-invasive alternative that engages the same deep target.
Editorial Notes
- This article was edited by a Neuroscience News editor.
- The journal paper was reviewed in full by the editorial team.
- Additional context and explanation were provided by staff to clarify implications and methodology.
About this neurotech and learning research
Author: Alan Williams, University of Plymouth
Source: University of Plymouth
Contact: Alan Williams, University of Plymouth
Image credit: Neuroscience News
Original Research: Open access. “Non-invasive ultrasonic neuromodulation of the human nucleus accumbens impacts reward sensitivity” by Elsa Fouragnan et al., published in Nature Communications.
Abstract
Non-invasive ultrasonic neuromodulation of the human nucleus accumbens impacts reward sensitivity
Precise, non-invasive modulation of deep brain regions has the potential to transform neuroscience research and clinical care. This study demonstrates that transcranial ultrasound stimulation (TUS) can selectively influence deep-brain activity in the nucleus accumbens and alter learning and decision-making in ways that are comparable to effects observed with deep brain stimulation (DBS).
In a within-subject TUS–fMRI experiment, 26 healthy adults underwent three conditions: TUS targeting the nucleus accumbens (NAcc), TUS targeting the dorsal anterior cingulate cortex (dACC), and a sham condition. Following stimulation, participants completed a probabilistic reinforcement learning task during fMRI. TUS applied to the NAcc modified BOLD responses to reward expectation in the target and surrounding areas and produced measurable changes in reward-driven behaviour, including increased use of win–stay strategies, higher learning rates after rewards, altered learning trajectories, and increased repetition of rewarded choices. Parallel observations in patients with DBS electrodes targeted to the NAcc supported the conclusion that both invasive and non-invasive approaches can engage the same reward-related mechanisms.
These results establish TUS as a promising method for non-invasive deep-brain neuromodulation with potential applications in research and future therapeutic interventions.