Neurological disorders affect millions of people in the United States and worldwide. Better understanding of the short-term changes and the persistent changes that result from precisely targeted electrical stimulation of brain networks can lead to novel technologies that improve diagnosis and treatment of these disorders. Intracranial recording/stimulation techniques using electrocorticographic (ECoG) electrodes on the brain surface and/or depth electrodes (stereoencephalography (SEEG)) provide a powerful method for spatially and temporally precise recording and stimulation, but current stimulation protocols are based largely on trial-and-error and thus are probably suboptimal. Taking optimal advantage of ECoG/SEEG requires the ability to design adaptive record- ing/stimulation protocols that induce specific beneficial changes in the brain processes underlying behavior. The work proposed here will address this need by creating a stimulation-based system that can map cortical/subcortical functional networks and can modulate these networks so as to restore brain function. TR&D3's long-term goal is to develop and iteratively optimize a new generation of adaptive neurotechnologies that can introduce predictable changes in brain networks, and to clinically test the efficacy of those technologies for alleviating the devastating effects of neurological disorders such as stroke. To achieve this goal, TR&D3 has two Specific Aims: Aim 1. To establish the short-term changes in network activity and resulting behavior that are produced by electrical stimulation. Aim 1 comprises two studies. The first study will use electrical stimulation to establish which and how brain networks are activated by electrical stimulation of specific locations. The second study will determine how input produced by electrical stimulation interacts with moment-by-moment variations in cortical excitability to produce population-level responses. Aim 2. To establish the persistent changes to network activity resulting from electrical stimulation. The first study will determine to what extent stimulus-induced changes modify behavior in the short term and the long-term. The second study will assess the dependence of these changes on stimulus amplitude. These two aims will produce a stimulation-based functional imaging system. To validate and optimize this novel system, TR&D3 will engage in two collaborative projects with scientists at the University of California (Berkeley) and at MIT. Together, these collaborations will establish the effectiveness and value of the new stimulation-based functional imaging system. By accomplishing these aims, TR&D3 should produce new understanding of how electrical stimulation produces short-term and persistent changes in brain function. It should also create a new clinical system that can map brain networks and can target specific beneficial changes in function. Thus, this work should increase scientific understanding and enhance treatment for a range of neurolog...