Non-invasive treatment of neurological diseases has been a worldwide problem. However, safe and effective treatments for neurological disorders are largely lacking. The most effective treatment, implanted electrodes, is too traumatic to be universal.
Optogenetics is a revolutionary approach to optically modulate the activity of neurons developed in recent years. Scientists have found that certain bacterial ion channel proteins respond to blue or yellow-green light, opening and closing ion channels to stimulate or inhibit specific nerves. In 2005, scientists expressed these light-sensitive proteins in neurons for the first time, making it possible for light to control neural activity. However, the blue light that ion channel proteins can respond to has weak penetration, and how that blue light penetrates the brain tissue to reach the deep part of the brain is still a difficult problem.
Shuo Chen, a postdoctoral fellow at the University of California, Berkley, invented a groundbreaking method where he has succeeded in developing a minimally invasive deep brain stimulation technique that allows precise control of neurons by tissue-penetrating near-infrared light (NIR). To be specific, he employed upconversion nanoparticles in the deep brain to convert tissue-penetrating NIR into blue-green light for optogenetically activating close-by neurons. NIR, on the other hand, is easier to penetrate biological tissue. This makes it possible for scientists to control neurons.
Chen's achievement is largely thanks to his cross-disciplinary backgrounds in synthetic chemistry and neuroscience. From 2008 to 2015, Chen conducted his Ph.D. in the Department of Chemical Life Engineering at the University of Tokyo. He stumbled upon news that the RIKEN Brain Science Institute was providing one-year training in brain science, which piqued his interest in brain science.
However, there were not many previous materials to refer to in this cross-cutting area. "No funds and no equipment when we started," described Chen at that time. One day, he used infrared light to test the ventral tegmental area of an experimental mouse, successfully detecting dopamine downstream, proving the feasibility of this method. With great support from his supervisor, Dr. Thomas McHugh, he expanded the technology to applications in different brain regions, such as recalling memory engram in the hippocampus of the mouse brain.
From a conceptual perspective, Chen pioneered a new type of approach to non-invasive deep brain stimulation that relies on local energy conversion. Future efforts may underpin the transformation of NIR or ultrasound into heat, and the conversion of X-ray into visible light. When combined with the recently developed technology for non-invasive gene delivery to the brain, truly non-invasive high-precision deep brain stimulation without surgical intervention can be realized.
Chen hopes to make more contributions to the treatment of brain diseases in the field of brain science in the future.