A major goal of neuroscience research is to understand the neural changes that underlie adaptations of the motor system and to use this understanding to promote healing after injury. David McVea is studying the role of sensory input in this process from two different perspectives. First, he is testing the idea that muscle spindles, which respond to changes in muscle length, help determine when changes in the motor system are needed and subsequently spur changes in neural circuits. Second, he is studying how spontaneous muscle twitches in very young animals provide sensory feedback that helps to calibrate and organize the brain’s motor circuits. Mr. McVea is using unique optical recording and stimulating techniques to address these topics. Voltage- and calcium-sensitive dyes allow for simultaneous recording of neurons that are active across large regions of the brain. At the same time, lasers can be used to activate any part of the surface of the brain in mice that express the light-sensitive ion channel Channelrhodopsin-2. Because dyes and laser light are applied to the intact surface of the brain, all neural networks and connections are intact, meaning findings are representative of natural functions. This research will provide valuable information about the fundamental ways in which the human brain develops and recovers after injury. Furthermore, the results could inform the development of new treatments that increase or even artificially enhance sensory feedback to maximize the recovery of people who have suffered brain injury.