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Objective: To explore regional brain activity changes during neural processing of human stereopsis by subtracting and reverse subtracting. Methods: Ten healthy volunteers participated in our fMRI experiments. Each subject performed two different vision-related tasks: plane figure and stereogram stimulations. After preprocessing, data were analyzed with SPM 99 software. We employed reverse subtracting method to obtain the group averaged deactivation maps. Results: There are two major findings in our study. The deactivated brain areas appear to be task dependence. Of plane figure stimuli, deactivation were mainly centered on default mode network, and with stereogram stimuli induced deactivation in regions of fusiform gyrus, thalamus and claustrum. Furthermore, task independent deactivation were observed in the medial frontal gyrus, superior temporal gyrus and insula. Conclusion: Our data further supported the notion that default mode network activity does exist during resting state. Nevertheless, stimulus is an important contribution to deactivation and should be considered when exploring the phenomenon of deactivation. Brain resources can be allocated automatically and continuously according to different task performance.

Objective: To study the differences of gray and white concentration and the amplitude of low-frequency fluctuation (ALFF) in resting-fMRI between male and female brains. Methods: Twenty male and twenty female graduate students underwent both anatomical MRI and resting-state fMRI scanning sessions. Voxel-based morphometry (VBM) was applied on structural magnetic resonance images and ALFF in the resting-fMRI was calculated. After data preprocessing, the relative concentration of gray and white matter and the ALFF in male and female brains were compared using a two-sample t-test. Results: Increased gray matter concentration in females versus males was observed in the superior parietal lobule, pre- and postcentral gyrus; Increased white matter concentration in females versus males was observed in the right genu of corpus callosum, superior parietal lobule and orbitofrontal cortex (OFC); And increased ALFF was observed in the right genu of corpus callosum, left medial and middle frontal gyrus, right posterior cingulate gyrus and subcallosal gyrus in female group compared to male group. Conclusions: The neural activities in prefrontal and posterior cingulate cortex within the default mode network (DMN) in women are stronger than in men; Sex difference in neural activity of right genu of corpus callosum is related to sex difference in volume of right genu of corpus callosum; Females have larger white matter concentration in right genu of corpus callosum and right OFC, which confirm prior reports of sex differences in OFC and corpus callosum structure.