A new method for exploring the human brain without surgery has been successfully tested by researchers. This non-invasive brain stimulation technique shows promise for understanding and treating various neurological and psychiatric conditions, without the need for surgery or implants. Neurological disorders like addiction, depression, and obsessive-compulsive disorder (OCD) impact millions of people globally and involve complex pathologies affecting multiple brain regions and circuits.The treatment of neurological and psychiatric conditions has been tricky because of the complexity of brain functions and the difficulty of delivering therapies to deep brain structures without invasive procedures. Non-invasive brain stimulation is a promising development in the field of neuroscience, offering hope for better understanding and treatment of various conditions without the need for surgery or implants. Friedhelm Hummel, who holds the Defitchech Chair of Clinical Neuroengineering at EPFL’s School of Life Sciences, and postdoc Pierre Vassiliadis are at the forefront of this new approach.eld, unlocking new possibilities for addressing issues such as addiction and depression.
By utilizing transcranial Temporal Interference Electric Stimulation (tTIS), their study focuses on specific regions deep in the brain that play a crucial role in various cognitive functions and are linked to a range of neurological and psychiatric disorders. The findings, which appear in Nature Human Behaviour, underscore the collaborative nature of the research, which brings together medicine, neuroscience, computer science, and engineering to enhance our comprehension of the brain and potentially create transformative treatments.
“Invasive deep braiDeep brain stimulation (DBS) has shown success in treating addiction, Parkinson’s, OCD, and depression by targeting the neural control centers. The unique aspect of this new approach is that it is non-invasive, using low-level electrical stimulation on the scalp to reach these regions,” says Hummel. Vassiliadis, the lead author, explains that tTIS involves using two pairs of electrodes on the scalp to apply weak electrical fields inside the brain. This non-invasive technique allows for specific targeting of these regions, which was not possible before.The use of electrical fields to stimulate different areas of the brain between the surface of the skull and the deeper regions has been found to render existing treatments ineffective. This new method allows for targeted stimulation of deep brain regions that play a crucial role in neuropsychiatric disorders,” he says.
This groundbreaking technique is based on the idea of temporal interference, which was first studied in rodent models and has now been successfully applied to humans by the EPFL team. In this experiment, one pair of electrodes is set to a frequency of 2,000 Hz, while another pair is set to 2,080 Hz. Detailed computational models of the brain structure are used to space the electrodes accordingly.The signals are specifically placed on the scalp to ensure that they intersect in the target region. When the frequency of the two currents is slightly different (80 Hz), the magic of interference happens and creates an effective stimulation frequency within the target zone. This method is brilliant because it is selective in its stimulation, leaving the intervening brain tissue unaffected and focusing the effect solely on the targeted region, while the high base frequencies such as 2,000 Hz do not directly stimulate neural activity. The latest research focuses on the human striatum, a crucial area.The focus of the study is on reward and reinforcement mechanisms. Vassiliadis explains that they are investigating how reinforcement learning, which involves learning through rewards, can be impacted by targeting specific brain frequencies. Through stimulation of the striatum at 80 Hz, the team discovered that they could interfere with its normal functioning, directly influencing the learning process.
The potential for therapy resulting from their research is significant, particularly for conditions such as addiction, apathy, and depression, where reward mechanisms play a critical role. Vassiliadis suggests that their method could potentially help in reducing the pathological overemphasis on rewards, as seen in addiction cases.Vassiliadis, a researcher at UCLouvain’s Institute of Neuroscience, noted that the team is investigating how various stimulation patterns can not only interfere with but also potentially improve brain functions. “Our initial goal was to demonstrate the impact of 80 Hz on the striatum, and we were successful in disrupting its functioning. Our research also suggests potential for enhancing motor behavior and increasing striatum activity, especially in older adults with reduced learning abilities,” Vassiliadis explains. Hummel, a trained neurologist, views this technology as the beginning of a new era in brain stimulation.The research team is focused on developing personalized treatment using less invasive methods. They are aiming for a non-invasive approach that allows for personalized treatment for deep brain stimulation in the early stages. One of the major benefits of this approach is its minimal side effects. In their studies, most participants only reported mild sensations on the skin, making it a highly tolerable and patient-friendly approach.
Hummel and Vassiliadis are hopeful about the potential impact of their research. They believe that in the future, non-invasive neuromodulation therapies could be widely available in hospitals, providing a cost-effective and comprehensive treatment option.
