Glenn T. Stebbins, Ph.D. Associate Professor, Neurological Sciences and Psychology Education B.A. (1974) – San Francisco State University, San Francisco, California (Psychology) M.S. (1985) – University of Arizona, Tucson, Arizona (Clinical Psychology) Ph. D. (1987) – University of Arizona, Tucson, Arizona (Clinical Psychology) Contact Information Address: Rush University Medical Center Department of Neurological Sciences 1725 West Harrison, Suite 309 Chicago, IL 60612

Business Phone: (312) 563-3854 Business FAX: (312) 563-4009 E-mail Address: gstebbin@rush.edu Research Interests Dr. Stebbins' research interests center on the effects of normal and pathological aging on cognitive function in humans. Using advanced neuroimaging (e.g., fMRI, Diffusion Tensor Imaging, SPECT) and behavioral techniques, studies are designed to assess the relationship between structural and functional changes in the CNS and age-related behavioral changes. Specific areas of interest include the contribution of white matter microstructural integrity to cortical and subcortical gray matter function during executive and declarative memory performance. Current research focuses on four areas: 1) Dissociation of cortical and sub-cortical contributions of executive working memory impairments in patients with movement disorders. 2) Delineation of medial temporal lobe functional activity during declarative memory performance in patients with Alzheimer's disease, mild cognitive impairment, 3). Examining the contribution of "normal appearing" white matter integrity to perceptual motor processing speed and executive working memory performance in patients with ischemic stroke. 4). Decomposing the influence of lesion pathology on cognitive function in patients with multiple sclerosis. Figure 1. Representative regions of significant differences in white matter DTI results between younger and older participants. 1A displays regions of significantly increased mean diffusivity (DW) in older participants compared to younger participants. 1B displays regions of significantly reduced intra-voxel anisotropic diffusion (FA) in older participants compared to younger participants. 1C displays regions of significantly decreased inter-voxel coherence (CI) in older compared to younger participants. 3D volumes were created from contiguous individual slices and normalized to a common standardized brain volume using SPM99 (Friston, Holmes, Worsley et al., 1995). Differences were analyzed using a two-sample t-test statistic. Significance thresholds were set for p < .05 for both height and extent of activation (Friston et al., 1994). Voxels evidencing significant differences between groups are displayed on representative axial sections (z = 0, +12, +24, +36) on a connonical brain image. The color scale indicates the magnitude of t values with lowest appearing in dark red and the highest in bright yellow/white. The left side of the images represents the left side of the brain. Figure 2. Regions of significant activation for younger (top row) and older (botton row) participants during semantic versus non-semantic encoding. 3D volumes were created from contiguous individual slices and normalized to a common standardized brain volume (Talairach & Tournoux, 1988). These composite images are displayed on coronal sections (y = +8, +20, +28, +32) from the stereotaxic atlas of Talairach and Tournoux (1988) corresponding to the nearest coordinates of the individually acquired slices. The color scale indicates significance of correlation magnitudes with lowest appearing in dark red (p < .01) and the highest in bright yellow/white. The left side of the images represents the left side of the brain. Representative Publications Stebbins, G. T., Carrillo, M. C., Dorfman, J., Dirksen, C., Desmond, J., Turner, D. A., Bennett, D. A., Wilson, R. S., Glover, G, & Gabrieli, J.D.E. (2002). Aging effects on memory encoding in the frontal lobes. Psychology and Aging, 17, 44 - 55. Stebbins, G. T., Gabrieli, J. D. E., Shannon, K. M., Penn, R. D., & Goetz, C. G. (2000). Impaired fronto-striatal cognitive functioning following posteroventral pallidotomy in advanced Parkinson’s disease. Brain and Cognition, 42, 348-363. Stebbins, G. T., Gabrieli, J. D. E., Masciari, F., Monti, L. A., & Goetz, C. G. (1999). Delayed recognition in Parkinson's disease: A role for working memory? Neuropsychologia, 37, 503-510.