Reaching for a pen to write or a tool to hammer a nail are the kinds of intentional actions produced every day. This project will advance our understanding the conscious control of behavior by investigating the neural mechanisms that underlie the sense of agency – the feeling that one has both intended to and executed a particular movement. Scientists are now able to stimulate muscles electrically in order to enhance the performance of such routine movements. For some people, this externally stimulated action is felt to be the result of their own intentional control; for others, the action feels externally produced and not of their own agency. By measuring the distribution and timing of neural signals in these two situations of stimulated action that is felt to be intentional compared to movements that are felt to be externally controlled, the research will test cognitive and neural theories of consciousness and subjective experience in the initiation and control of behavior. The findings can lead to new ways of thinking about the neuroscience of action. They can also provide guidance for the improvement of user-system interfaces for robotic control and training methods for the future of work at the human-technology frontier, the development of new prosthetics as well as new rehabilitation therapies for the recovery of motor function following disease or trauma. This project is funded by Integrative Strategies for Understanding Neural and Cognitive Systems (NCS), a multidisciplinary program jointly supported by the Directorates for Computer and Information Science and Engineering (CISE), Education and Human Resources (EHR), Engineering (ENG), and Social, Behavioral, and Economic Sciences (SBE).
The research will enhance typically controlled human motor movements by manipulating them externally through functional electrical stimulation (FES), the use of a robotic exoskeleton, or the induction of illusory motion in order to probe the role of corollary discharge and reafferent signals in determining the time course and strength of the sense of agency. A set of six experiments will identify the role of agency in motor learning, the conditions under which agency is lost, and the extent to which voluntary movements can be externally modified without losing the sense of agency. Measurements of the activity and timing in the motor system and in somatosensory cortex using human electroencephalography (EEG) and functional Magnetic Resonance Imaging (fMRI) will be used to model neural responses. Measurements taken when enhanced movement is felt to be self-initiated will be compared to those taken when the movement is experienced as externally guided. This contrast between a sense of intentional agency in enhanced movement and passive unintentional movement will be related to the patterns of neural activity across different forms of external movement enhancement. The sense of agency for external stimulation of action has been predictive of improved motor learning and the neural signals related to agency will be used to model motor learning. These analyses will be used to test specific models of agency and consciousness in intentional action relating efferent motor cues, the striatal reward system, and learning. Understanding the neural mechanisms of conscious control of behavior can lead to new models for neuroengineering and brain-inspired design, provide new information about individual differences and variation in cognitive control of behavior and learning, and yield new understanding of how neural processes operate in realistic and complex environments.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
