Brainstem stroke and amyotrophic lateral sclerosis can lead to devastating disability, resulting in part from communication impairment and immobility. In the most severe cases, patients become locked-in - awake and alert, but unable to move, control their environment, or ask for help. In these disorders, as well as other neurologic diseases and injuries, the desire or intention to move remains fully intact, but the motor centers of the brain are disconnected from their targets in the brainstem or spinal cord, resulting in paralysis. The development and testing of a technology that enables someone with severe paralysis or locked-in syndrome to communicate independently and reliably would revolutionize the fields of assistive technology and neuroengineering, and would be critical steps toward re-enabling limb movement after paralyzing disease or injury. Based on encouraging preliminary findings from participants with tetraplegia and limited communication, this proposed translational research will seek to further develop a neural interface system that can record brain signals and permit persons with paralysis to control communication software, simply by imagining the movement of their own paralyzed arm or hand. Up to five participants with brainstem stroke or ALS will receive a 96-microelectrode array (4x4 mm) which will record the individual and summed activities of ensembles of neurons in the motor cortex. In addition to further assessing the safety of this implanted medical device, this research will support the development of reliable neural decoding algorithms that permit persons with paralysis to use their natural movement-related cortical signals to drive a communication device for speech synthesis and improved environmental control.