Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice

摘要

Mice use their whiskers to sense their environment and to detect nearby objects. Rather than simply allowing their whiskers to brush passively against objects, mice move them in rhythmic bursts in a process called whisking. Whisking enables neuroscientists to study how the brain gathers and processes actively acquired sensory information. However, controlling active whisker movements in the laboratory has proven challenging. Park et al. now offer a solution based on a technique called optogenetics. The new procedure involves introducing the gene for a light-sensitive ion channel into the facial muscles of the mouse. Shining blue light onto the area of skin where the whiskers grow – the whisker pad – activates these ion channels. Park et al. were able to use this technique to trigger the contraction of the facial muscles and the movement of the whiskers. Furthermore, stimulating different muscles in different areas of the whisker pad produced either forward or backward whisker movements. The strength of the whisker movements varied with the intensity of the light, and with how often and for how long light was applied. Recordings of neural activity showed that sensory signals from light-induced whisker movements reach the same region of the brain as signals from natural whisker movements. Behavioral experiments showed that mice could perceive these whisker movements, despite the fact that they did not generate them. By establishing a method for triggering whisker movements on demand, Park et al. have provided a convenient way of investigating active sensory processing. In addition, this method opens up new possibilities for using optogenetics after injury or degeneration of the nerves that control movement. Ultimately, by using light to trigger muscle contraction directly, it may be possible to restore movement in individuals who have sustained nerve damage through injury or disease.