HYPOFUNCTIONAL CONNECTIVITY BETWEEN MEDIAL PREFRONTAL CORTEX AND POSTERIOR CINGULATE CORTEX WITHIN THE DEFAULT MODE NETWORK IN TWIN AUTISM CASES WITH LOWER SOCIAL AND COGNITION/COMMUNICATION FUNCTIONING

Autism is a neurodevelopmental disorder characterized by core deficits in socialization and communication skills. Default Mode Network (DMN) is a large-scale brain network which part of the social-cognitive symptoms that define autism. In the recent meta-analytic review based on rs-fMRI data have revealed hypofunctional connectivity in anterior (Medial Prefrontal Cortex-MPFC) and posterior (Posterior Cingulate Cortex -PCC) midline regions of DMN in autism which associated with social communication deficits. Based on this theoretical hypothesis, the aim of this study is to examine DMN activities of twin autism children with low IQ and to associate them with Turkish Vineland Adaptive Behavior Scale- II Profile scores. Twin autism sibling was selected from the Turkish Vineland-II autism group: OTREST1: autistic boy, NOTREST1: healthy girl, OTREST2: autistic boy, OTREST3: autistic boy. rs-fMRI and structural scans acquired at UMRAM (Bilkent University, Ankara) using 3 Tesla MRI. Raw rs- fMRI images of 2 twin pairs were spatially and temporally preprocessed using FMRIB Software Library, SPM 12; rs-fMRI functional connectivity analysis was calculated with MATLAB R2019R, CONN Program. DMN seeds were centered at MNI stereotaxic coordinates x=1, y=−61, z=38 for PCC and x= 1, y=55, z=−3 for MPFC. The results of seed-based ROI-to-ROI first- and second-level analyses showed that the autism group (p<0.05, FDR-corrected regions) had hypofunctional connectivity within DMN regions. The results obtained supported the hypothesis that there is a hypofunctional connectivity between MPFC and PPC of autistic twins with low adaptive functioning according to the Turkish Vineland-II Profile.