Adam J. Schwarz1, Vesa Kiviniemi2, Sara de Simoni3, Steven C. R. Williams3, Mitul A. Mehta3
1Translational Medicine, Eli Lilly & Company, Indianapolis, IN, United States; 2Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; 3Centre for Neuroimaging Sciences, Institute of Psychiatry, London, United Kingdom
PhMRI responses are often widespread, but the stability of the spatial localization of responses across subjects and cohorts at the voxel scale may be affected by neuroanatomical variation, motion and residual differences in spatial normalization. We show that the phMRI response to ketamine can be accurately and sensitively modeled as a linear superposition of stable, independently derived, functional units. The concept is illustrated using a high model order ICA segmentation of the brain. Such functional units can be spatially distributed and overlapping, unlike anatomical VOIs, and may be robust to high spatial frequency differences across subjects.