1. Hamot Hospital; University of Pittsburgh Medical Center; Erie Pennsylvania USA
2. Department of Neurosurgery, University of Illinois at Chicago; 912 South Wood Street Chicago; IL 60612
3. Department of Biomedical Engineering; Carnegie Mellon University, 5000 Forbes Avenue; Pittsburgh PA 15213
4. Human Motor Control Section; National Institute of Neurological Disorders and Stroke; Bethesda Maryland USA