Sawyer, K. | Search bioRxiv

bioRxiv2018

Alcoholism Gender Differences in Brain Responsivity to Emotional Stimuli

Men and women may use alcohol to regulate their emotions differently, with corresponding differences in neural responses. We examined how photographs of emotional stimuli impacted brain activity obtained through functional magnetic resonance imaging (fMRI) from 42 alcoholic (25 women) and 46 nonalcoholic (24 women) participants. Brain responsivity was blunted in alcoholic compared to nonalcoholic groups. Further analyses indicated significant gender differences in the impact of alcoholism. Brain activation of the alcoholic men (ALCM) was significantly lower than that of the alcoholic women (ALCW) and nonalcoholic men (NCM) in regions including the inferior parietal gyrus, anterior cingulate gyrus, and postcentral gyrus, whereas activation was higher in the ALCW than in the nonalcoholic women (NCW) in superior frontal and supramarginal cortical regions. The reduced brain reactivity of ALCM and increases for ALCW highlighted divergent brain regions and gender effects, suggesting possible differences in the underlying basis for development of alcohol use disorders.

neuroscience↗

bioRxiv2017

Using Outliers in Freesurfer Segmentation Statistics to Identify Cortical Reconstruction Errors in Structural Scans

IntroductionQuality assurance (QA) is vital for ensuring the integrity of processed neuroimaging data for use in clinical neurosciences research. Manual QA (visual inspection) of processed brains for cortical surface reconstruction errors is resource-intensive, particularly with large datasets. Several semi-automated QA tools use quantitative detection of subjects for editing based on outlier brain regions. There were two project goals: (1) evaluate the adequacy of a statistical QA method relative to visual inspection, and (2) examine whether error identification and correction significantly impacts estimation of cortical parameters and established brain-behavior relationships.\n\nMethodsT1 MPRAGE images (N = 530) of healthy adults were obtained from the NKI-Rockland Sample and reconstructed using Freesurfer 5.3. Visual inspection of T1 images was conducted for: (1) participants (n = 110) with outlier values (z scores {+/-} 3 SD) for subcortical and cortical segmentation volumes (outlier group), and (2) a random sample of remaining participants (n = 110) with segmentation values that did not meet the outlier criterion (non-outlier group).\n\nResultsThe outlier group had 21% more participants with visual inspection-identified errors than participants in the non-outlier group, with a medium effect size ({Phi} = 0.22). Nevertheless, a considerable portion of images with errors of cortical extension were found in the non-outlier group (41%). Sex significantly predicted error rate; men were 2.8 times more likely to have errors than women. Although nine brain regions significantly changed size from pre- to post-editing (with effect sizes ranging from 0.26 to 0.59), editing did not substantially change the correlations of neurocognitive tasks and brain volumes (ps > 0.05).\n\nConclusionsStatistically-based QA, although less resource intensive, is not accurate enough to supplant visual inspection. We discuss practical implications of our findings to guide resource allocation decisions for image processing.

neuroscience↗