Summary: Researchers have successfully altered human reward learning using non-invasive transcranial ultrasound stimulation directed at a deep brain structure linked to motivation. After brief stimulation, participants learned faster from positive feedback and repeated rewarding choices more consistently.
The effects mirrored key aspects of surgical deep brain stimulation but without implants or incisions. The findings suggest ultrasound could become a safer, personalized tool for reshaping faulty reward circuits in mental health disorders.
Key Facts
- Deep Brain Targeting: Ultrasound successfully modulated the nucleus accumbens without surgery.
- Faster Reward Learning: Participants showed increased sensitivity to positive outcomes after stimulation.
- Therapeutic Potential: The technique may one day aid treatment for addiction, depression, and eating disorders.
Source: University of Plymouth
The nucleus accumbens is a tiny element of the human brain triggered when we experience something enjoyable, and used to help us learn behaviours that lead to rewards.
A new study has shown for the first time that its influence on human behaviour can be altered using transcranial ultrasound stimulation (TUS).
Applying the technique for just over a minute at a time, researchers were able to influence how people learned the links between certain cues and rewards.
The result was that they were more likely to repeat a choice that had previously paid off, their learning rates following positive outcomes increased and they were more likely to make positive choices more quickly.
Up to this point, such outcomes have only been achieved through surgical procedures such as deep brain stimulation (DBS), which involves electrodes being directly attached to areas within a person’s brain.
However, those involved in the current study say their findings could signal that TUS has the potential to be used as an equally beneficial – and non-invasive – alternative to help those impacted by neurological or psychiatric disorders including addictions, depression and eating disorders.
The study is published in the journal Nature Communications and was led by researchers from the University of Plymouth. It also involved 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 research.
She said: “For decades, the nucleus accumbens has sat at the centre of theories of motivation and reinforcement learning. It is the hub where dopamine signals and limbic inputs converge to shape how strongly rewards pull our choices.
“We were able to pinpoint a clear link between a specific learning trait, tied to impulsivity, and a structure that until now could not be reached without surgery. The fact that we can now modulate this area non-invasively, and in a personalised manner, opens extraordinary possibilities for clinical translation.”
The study forms part of ongoing and pioneering research taking place at the University of Plymouth into the benefits of TUS for conditions including anxiety and depression, addiction and other neurological or psychiatric disorders.
In this project, the researchers recruited 26 healthy participants who visited the BRIC facility four times – once to plan their TUS intervention, followed by three sessions where TUS was applied to different parts of their brain.
Roughly 10 minutes after the ultrasound intervention, participants were placed in the scanner to perform a series of tasks over the space of an hour while the research team monitored changes in their behaviour and brain activity.
The participants’ performance in the tasks was also cross-checked against that of patients with bilateral deep brain stimulation electrodes targeted to the nucleus accumbens as part of therapies for treatment-resistant anorexia nervosa.
The results showed that while DBS often normalises reward-seeking behaviour, TUS had an opposite and excitatory effect – however, both result in people’s learning and reward sensitivity being altered.
Professor Fouragnan added: “This study is the most significant I have had the privilege to lead so far. We uncovered a clear link between a specific cognitive process and a deep-brain structure that, until now, was beyond reach without surgery. It marks a turning point for neurotechnology, showing that a non-invasive ultrasound approach can influence behaviour and may one day help restore mental balance.”
Key Questions Answered:
A: A deep reward center called the nucleus accumbens that guides motivation and learning.
A: People learned faster from positive outcomes and repeated rewarding choices more often.
A: Similar effects previously required invasive brain surgery.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neurotech and learning research news
Author: Alan Williams
Source: University of Plymouth
Contact: Alan Williams – University of Plymouth
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Non-invasive ultrasonic neuromodulation of the human nucleus accumbens impacts reward sensitivity” by Elsa Fouragnan et al. Nature Communications
Abstract
Non-invasive ultrasonic neuromodulation of the human nucleus accumbens impacts reward sensitivity
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 expectation in the NAcc and surrounding areas.
It also affected reward-related behaviours, including win–stay strategy use, learning rate following rewards, learning curves, and repetition rates of rewarded choices. DBS-NAcc perturbed the same features, confirming target engagement.
These findings establish TUS as a viable approach for non-invasive deep-brain neuromodulation.
