PROJECT SUMMARY While current augmentative and alternative communication (AAC) devices present a variety of access methods for message generation to benefit people with complex communication needs, there still exists a group of literate adults with severe speech and motor impairments (SSMI) who cannot identify a functional means for typing, which is an important tool for computer-based communication. In prior NIDCD- supported research, our research team developed a high performance intracortical brain-computer interface (iBCI) that decodes movement intentions directly from brain activity. This technology has allowed people to control a cursor on a computer screen for communication simply by imagining movements of their own arm. The proposed R01 clinical research will extend this prior work on improving the performance of iBCI systems, as part of the multi-site BrainGate consortium, and utilizing a new fully- implantable, wireless system being developed under separate NIH BRAIN Initiative funded project. The goals of the project are to leverage the discovery of new motor and cognitive signals in human motor cortex to implement and evaluate three new methods for iBCI typing and general purpose computer use: (1) an automatic Error Detect and Undo (EDU) system that uses error-related signals from motor cortex, (2) decoding techniques that create continuous high degree-of-freedom control signals from motor cortex to increase rates of point-and-click iBCI typing in 3D and 4D as compared with 2D, and (3) decoding techniques that classify multiple different “click” signals from motor cortex. A rigorous uniform experimental procedure with clear evaluation metrics will be utilized across all three Specific Aims, in all three research participants, and at each clinical site using a standardized suite of iBCI tasks, assuring consistency across sessions and participants. Upon completion, this project will advance both the capabilities of iBCIs for communication and our understanding of the function of human motor cortex.