Brain Structural Plasticity Associated with Maternal Caregiving in Mothers: A Voxel- and Surface-Based Morphometry Study

<b><i>Background:</i></b> Pregnancy constitutes a significant period in the lives of women, after which they often experience numerous crucial physiological and psychological changes. Functional neuroimaging studies have shown longitudinal changes in functional brain activity in mothers responding to infant-related stimuli. However, the structural changes that occur in the brains of mothers after delivery remain to be explored. <b><i>Objective:</i></b> We aimed to evaluate the structural changes in mothers during the postpartum phase. <b><i>Methods:</i></b> We recruited 35 primiparous mothers and 26 nonmothers to participate in this voxel- and surface-based morphometry study, and 22 mothers were scanned twice with a follow-up of approximately 2 years. <b><i>Results:</i></b> Compared to nonmothers, mothers exhibited reduced gray matter (GM) volumes and increased white matter (WM) volumes in regions associated with empathy and reward networks (supplementary motor area, precuneus, inferior parietal lobe, insula, and striatum), decreased cortical thickness in the precentral gyrus and increased gyrification index in the orbitofrontal cortex. Furthermore, mothers showed longitudinal changes in the GM and WM volumes and cortical thickness of several of these regions (including the superior and medial frontal gyrus, insula, limbic lobe, superior and middle temporal gyrus, and precentral gyrus), which have been associated with maternal networks during the postpartum period. Additionally, the changes in GM and WM volumes were related to changes in empathetic abilities in mothers. <b><i>Conclusion:</i></b> These results suggest that the brains of mothers exhibit adaptive structural dynamic plasticity. These findings provide a neuroanatomical basis for understanding how mothers process emotional sensory information during the postpartum period.