Effect of somatosensory electrical stimulation on hand choice
Hand selection is an unconscious decision often made in daily life, whether reaching for an object such as a cup or performing any other task. This decision is influenced by information about the object, such as the object’s location, shape, and orientation. However, when goal-relevant factors are similar for the left and right hands, the probability of selection for each hand is balanced. Recent findings suggest that in such ambiguous situations, hand selection is influenced by prior information prior to target presentation. One factor is previous somatosensory stimulation of one wrist, which may influence brain activity and thus increase the likelihood of selecting the stimulated hand. This phenomenon highlights an interesting connection between sensory input and motor decision-making.
A research team led by Kento Hirayama, Ph.D., of Waseda University and the University of Southern California, along with Rieko Osu, Ph.D., of Waseda University and Toru Takahashi, Ph.D., of Waseda University and the Laureate Brain Institute, have now explored how somatosensory stimulation can affect the location of the wrist. Influencing hand selection decisions. Research suggests that applying sensory stimulation to the median and ulnar nerves at the wrist may influence subsequent motor decisions, thereby increasing the likelihood of using the stimulated hand in tasks that require choosing one hand to reach a target as quickly as possible. The sensation of stimulation appears to influence the brain’s motor decision-making system, subtly guiding the individual to choose the stimulated hand. The study was published in the journal scientific report September 30, 2024.
The research team conducted a series of experiments in which healthy participants were asked to perform hand selection tasks while receiving unilateral wrist somatosensory stimulation at 0, 300, or 600 milliseconds before target presentation. Results revealed a clear pattern in that participants were more likely to use the stimulated hand for targets around the central region, whereas selection was difficult to determine based on target information. In peripheral areas where target information is effective, the hand ipsilateral to the target tends to be selected regardless of the stimulus. These findings suggest that peripheral sensory input may influence motor decisions, particularly in ambiguous situations of hand selection, revealing a previously underappreciated role of somatosensory in guiding hand selection. Furthermore, unilateral electrical stimulation of the wrist resulted in faster reaction times than bilateral wrist stimulation and no stimulation conditions, suggesting that targeted sensory input can facilitate the decision-making process.
“This research may open new treatment avenues to promote use of paralyzed hands and improve function in people with movement disorders such as stroke survivors,” Hirayama said. “Through the application of controlled somatosensory stimulation, it may be possible to bias motor decisions in a way that encourages more efficient use of the affected hand, which could support recovery and rehabilitation”.
In addition to clinical implications, research also contributes to our understanding of the fundamental processes involved in motor decision-making. By showing that the brain integrates sensory input from the body to guide action, the study adds a new dimension to our knowledge of how the brain controls movement and responds to environmental cues.
As the field of neurorehabilitation continues to advance, understanding how peripheral sensory signals influence movement selection may provide more effective, personalized treatments for patients with movement disorders.
“Overall, our study lays the foundation for the development of a compact, lightweight, affordable, and easy-to-use rehabilitation device that can be combined with traditional rehabilitation methods to enhance motor function recovery,” Hirayama concluded road.
2024-12-19 20:24:14