The paternal brain: longitudinal insights into structural and functional plasticity and attachment over 24 weeks...

Over the last two decades, interest in the neurobiological basis of parenthood has grown, with the primary focus being on maternal neuroplasticity. However, research on paternal brain adaptations remains limited and inconclusive. This longitudinal study investigated gray matter volume (GMV) and resting-state functional connectivity (rsFC) changes in 25 fathers immediately after childbirth and at 3, 6, 9, 12, and 24 weeks postpartum. Morphological changes were most evident as reductions in GMV within the bilateral occipital, frontal, temporal and parietal cortices, as well as the temporo-parietal junction, and the insular and hippocampal regions during the first six weeks, followed by gradual stabilization. From 12 weeks onward, local GMV increases were observed in the frontal and cerebellar regions. Connectivity analysis revealed significant reorganization within the Salience, Default Mode, and Frontoparietal Networks, with peak changes during the first 9 weeks marked by a shift from sensory processing to enhanced cognitive and affective processing. Additional rsFC analysis identified increased amygdala-cingulate and amygdala-hippocampal connectivity, indicating a significant link between the amygdala and paternal attachment during the first 12 weeks. These findings outline a clear trajectory of paternal neuroplasticity and adaptation during the early postpartum period, followed by maintenance and fine-tuning processes that likely facilitate paternal caregiving behaviors. Clinical Trial Registration: The study was registered at the German Clinical Trials register (DRKS; ID: DRKS00024875).