http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11222799&dopt=Abstract
Neurology 2001 Feb 27;56(4):526-8
Boroojerdi B, Phipps M, Kopylev L, Wharton CM, Cohen LG, Grafman J.
Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.