134. Functional Hyperengagement of the Corpus Callosum in Schizophrenia During Visuo-Motor Processing

Abstract

Background: Schizophrenia (SCZ) is associated with structural impairments in the corpus callosum (CC; Diwadkar, et al., 2004; Zhuo, et al., 2016), yet structural defcits do not necessarily predict dysfunction (Diwadkar et al., 2011). Here we explored CC dysfunction in SCZ using fMRI. Whereas the use of fMRI to identify activations in white matter is atypical, reliable and replicable white matter activations are induced using specifc tasks such as the Poffenberger paradigm (PP) (Chaumillon, et al., 2014; Mazerolle, et al., 2008). The PP induces inter-and within-hemispheric transfer (IT and WT) by leveraging the contralateral organization of the sensorimotor system: If a probe is briefy presented to one visual hemisphere (e.g., right visual cortex), information must cross the interhemispheric commissure depend-ing on the response hand used (e.g., Right hand-Left motor cortex; Left Hand-Right motor cortex; Marzi, 1999). Here we studied differences in CC activation between SCZ and healthy controls (HC) using the P P. Method(s): fMRI data (Siemens 3T) were acquired in 28 age-and gender-matched SCZ patients and HC. Data were processed in SPM8 using established methods. Group (HC vs. SCZ) and task-condition (IT vs. WT) were modeled at the 2nd level in a 2-way analysis of variance. Within this overall design, directional contrasts were used to disambiguate main effects of group, condition and/or interactions (P