The brain-computer interface can directly repair the motion perception function, help high paraplegia patients, patients with gradual frostbite, and blind patients recover their ability to live independently and communicate, and can also treat some mental diseases by regulating the nerves. It has broad applications in the fields of neurology and mental health prospect. The non-implantable brain-computer interface does not require implantation surgery and is highly accepted by the public. After its signal quality and control accuracy are improved, it may be widely promoted in the future.
Recently, Xiong Zhiqi’s team, a researcher at the Brain Science and Intelligent Technology Excellence Innovation Center of the Chinese Academy of Sciences, published an article in “Brain Stimulation”, reporting the team’s new progress in the study of low-intensity ultrasound directly regulating the neural activity of the cerebellar cortex. The practical application of non-implantable brain-computer interface technology has taken another step forward.
Emerging Focused Ultrasound Technology
The core of the brain-computer interface is to give full play to the advantages of the human brain, bypassing other organs of the human body, and allowing the brain to directly and efficiently interact with external equipment. A major challenge in this field is to strike a balance between minimizing brain damage and maximizing brain utilization.
There are still differences between non-implantable brain-computer interfaces and implantable brain-computer interfaces in terms of neural signal quality and neural regulation accuracy. However, non-implantable brain-computer interfaces do not require implantation surgery. If side effects occur, they can be eliminated The acceptance of the public will also be higher.
The key to the brain-computer interface is neuromodulation technology—targeted delivery of stimuli (such as electromagnetic stimulation, chemical reagents, etc.) to specific nerve parts to regulate neural activity.
At present, non-implantable neuromodulation technologies mainly include transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), which can be used for the treatment and diagnosis of mental diseases. In addition, there is the emerging focused ultrasound (FUS). Relatively speaking, focused ultrasound has the advantages of high spatial precision, strong penetrability, and specific effect on deep brain regions.
Previous related research mainly focused on the neuromodulation effect of ultrasound on some areas of the brain, but the potential of ultrasound to regulate cerebellar activity has yet to be explored.
Experiments in mice confirmed the effectiveness
In this study, mice with a point mutation in the proline-rich transmembrane protein 2 (Prrt2) gene (deficiency of Prrt2) were stimulated with ultrasound in their cerebellar cortex to exhibit dyskinesias, partially covering paroxysmal Symptoms of sexual movement-induced dyskinesia (PKD). Compared with sensory-induced muscle responses, such behavioral responses are more intuitive and convincing.
Low-intensity ultrasound induces reversible increases in neuronal activity in the cerebellar cortex and reliably triggers behavioral responses in mice with point mutants of the Prrt2 gene, the study showed.
The study also ruled out the influence of peripheral auditory pathways and indirect auditory mechanisms (such as stressors, foot shocks, caffeine, ethanol, running, etc.), confirming that low-intensity ultrasound does have a regulatory effect on the cerebellar cortex of mice.
In experiments, changes in neural activity could be observed that persisted beyond the duration of the stimulus. This result, which may be caused by changes in neuronal excitability, is an important idea for developing rehabilitation strategies based on non-invasive neuromodulation. This experiment is the first time that scientists have observed the persistent effect of ultrasound stimulation at the cellular level, which also proves the universality and heterogeneity of ultrasound-induced persistent effects on cerebellar cortical neurons.
Further experiments using a genetically encoded voltage indicator (also known as a genetically encoded membrane potential probe, a transmembrane protein that directly converts neural membrane potential into a fluorescent signal) with higher temporal resolution may lead to further experiments, the researchers said. More details will be provided to unravel the complexities of neural circuits.
