Physiology of Voluntary Movement

点击翻译按钮获取中文摘要

A number of efforts in the laboratory are devoted to understanding the physiology of volition. This includes the sense of willing to make a movement and the sense of agency, that you are responsible for the movement that has occurred. We have been trying to devise improved techniques to get quantitative measures of the timing of these subjective events. To determine which areas of the brain are activated with the sense of agency when making voluntary movement, we have developed an MRI-compatible dataglove which subjects will wear while making hand movements in the scanner. Subjects will be able to view their movements in real-time and the visual feedback they receive will be varied during the experiment to simulate different degrees of voluntary control. Correlative EEG studies will also be done. We are trying to determine EEG and MEG methods to predict in real time when someone is going to move and what movement they will make. We have optimized features and classification methods for the prediction. In specific experiments, we are trying to predict whether movement will be with the right or left hand or whether someone will move their right hand into the left or right spatial field. The work should be relevant for use with a brain-computer interface, as well as being useful to understand the physiology of volition. The learning of motor skills is an important function. We have been studying how movements become automatic, that is, the stage of learning where much attention does not need to be devoted to an action. Another feature of automaticity, that has not been studied, is how movements deteriorate at the automatic stage when attention is devoted to them. We will look at these phenomena with fMRI, TMS and EEG. We will use information learned in these studies to investigate patients with focal hand dystonia. The ability to make selective movements, particularly of individual fingers, is a critical human function. Anatomical and physiological features of the motor system make this difficult since most neurons (other than alpha motoneurons in the spinal cord and brainstem) are not muscle specific. Our hypothesis is that selective motor action must require inhibitory mechanisms, and we are seeking to understand them using TMS. We refer to this process as surround inhibition, as muscles not intended for the selective action need to be inhibited. Many inhibitory processes in the cortex, such as short intracortical inhibition and short afferent inhibition, can be analyzed at rest and with movement. Such studies should reveal which mechanisms are responsible for surround inhibition.