In a groundbreaking study, scientists have successfully used a new noninvasive brain stimulation method to modulate deep brain activity, leading to improved motor learning, especially in older adults. This discovery, published in Nature Neurosciencehas significant implications for understanding brain function and may pave the way for new treatments for various brain disorders.
Prior to this study, scientists used mainly invasive methods or less targeted non-invasive techniques to study deep brain structures such as the striatum, which are critical for motor learning. These traditional methods require surgical procedures or cannot specifically target deep brain regions without affecting them. Recognizing these limitations, researchers sought a precise, non-invasive way to stimulate these deep brain regions to better understand and improve motor learning processes.
“Mental disorders impose personal and financial burdens on society, harm patients and their families, and cost the EU nearly €1 trillion annually,” the study’s authors said. Fredhelm HummelHe holds the Defich Chair in Clinical Neuroengineering at EPFL’s School of Life Sciences.
“Developing effective treatments for these disorders is challenging due to the complexity of the brain and its symptoms. Current treatments, such as psychotropic drugs, are not based on recent advances in neuroscience and neurotechnology, and have limited efficacy and side effects. Of particular concern are conditions such as schizophrenia, stroke, dementia, Treatment-resistant symptoms occur in up to half of patients with major psychiatric disorders who have addiction or depression.
“Addressing this unmet need will require a new vision and new solutions,” Hamel said. “These diseases and symptoms are characterized by brain network interactions associated with key structures in the brain such as the striatum or hippocampus. Therefore, these structures are promising targets for neuromodulation-based intervention strategies.”
“Current neurotechnology allows us to target only these areas. Invader Due to the limitations of current non-invasive procedures such as TMS. However, invasive approaches pose several risks of side effects and face acceptance especially in mental health disorders. Therefore, it is very important to prepare a novel Non-invasive Neurotechnologies to specifically target these deep brain regions to pave the way for new treatments for the incomplete symptoms of these mental health disorders.
“The current concept of transcranial transient electrical stimulation (tTIS) allows us to solve this mentioned gap and weaknesses, so we have addressed this topic in a series of studies,” Hummel told PsyPost. “For this purpose, we chose the striatum as a target because it is involved in the pathophysiology and is a key site for recovery from many neurological and psychiatric disorders such as stroke, addiction, anxiety, depression or neurodegenerative disorders such as Parkinson’s spectrum.”
The study included 45 healthy participants and was divided into two experiments. The first experiment involved 15 young adults performing a functional magnetic resonance imaging (fMRI) sequence of a finger tapping task. The researchers used tTIS to modulate striatal activity during this task, using a sequence of electrical pulses, known as theta bursts, to alter brain activity in their human participants.
In the second experiment, the research group included both older adults (average age 66) and young adults (average age 26). They performed the same tasks under tTIS, but with longer practice blocks and a shorter overall training duration, to test whether the effects of the technique were consistent across different ages and training protocols.
In the first experiment, the researchers found that brain stimulation led to increased activity in the putamen, a brain region involved in motor learning during finger tapping. This effect was more pronounced in the putamen than in the other part of the stroke, the caudate. In particular, the increased activity in the putamen is associated with improved performance in motor tasks. In addition, they observed that the stimulation affected the brain’s motor network, including regions such as the thalamus and supplementary motor area.
“There is now the first proof of concept that deep brain structures can be neuromodulated, meaning that brain activity is altered and behavior can be modified non-invasively,” Hamel explained. This affects deep brain structures such as the striatum or hippocampus, such as Alzheimer’s disease, stroke, traumatic brain injury, depression, addiction, anxiety or movement disorders. It also provides a means to better understand the functioning of the brain, and particularly the role of deep brain structures in humans.
In a second experiment, the effect of brain stimulation was particularly strong in older people. The older group showed greater improvement in motor function during brain stimulation compared to the younger participants. This finding suggests that the technique may be particularly useful for older individuals with reduced motor learning abilities.
“The effects we found in healthy older adults were surprisingly strong,” Hummel told PsyPost. “In a short training period of less than 30 minutes, the stimulation showed an improvement of more than 30% compared to the placebo condition.”
However, it is important to note some caveats. The success of the technique depends on the presence of task-related brain activity. In other words, the stimulation did not induce changes in the resting state. This difference suggests that brain stimulation works best in conjunction with active learning processes. Moreover, the study mainly focused on the short-term effects and the long-term effects are not clear.
“There are still many open questions to be solved in future studies, such as a better understanding of the underlying mechanism, tailoring the stimulation to the individual, better localization of the stimulation, biomarkers to predict the treatment response, above all clinical translation (studies in this regard are ongoing)” he said. Hamel said.
The study “Noninvasive theta-burst stimulation of the human striatum improves striatal activity and motor skill learning.Authored by Maximilian J. Morishita, Antonino M. Cassara, Melanie Steiner, Nir Grossman, Isra Neufeld, and Friedhelm C. Hummel.