ACKNOWLEDGEMENTS First, I want to thank my Chairperson, Dr. Dawn Bowers, for teaching me the skills needed to become a competent researcher and writer. I also want to thank Dr. Russell Bauer for explaining psychophysiological methodology to me in a way that I could easily understand. I am also grateful to Dr. Heilman for being available to answer my questions about neurology, help me to choose patients, and map out the CT/MRI scans. I would like to thank my other committee members, Drs. Bradley, Rao, and Fennell for contributing their time and expertise to this project. Additionally, I would like to thank the many people who provided technical support for this project. Samel Celebi wrote all the computer porgrams and set up the interface between hardware and software. Barbara Haas taught me appropriate electrode placement and forced me to use an impedence meter. I am also grateful to those individuals at the West Roxbury VAMC who helped me to finish this project. Bill Milberg provided me with the time and computer facilities needed to conduct data reduction and analyses. Patrick Kilduff patiently helped me to reduce the tremendous amount of data I had collected. Also, Gina McGlinchy 11