Gray matter volume increase in the retrosplenial/posterior cingulate cortices of blind soccer players

Spatial navigation is a crucial brain function that occurs when an individual moves from one location to another. This function normally relies on vision, and the retrosplenial/posterior cingulate cortices (RSC/PCC) and parahippocampal cortex (PHC) play crucial roles. However, an extraordinary adaptation can be observed in blind soccer players, where the human brain can perform spatial navigation without vision. Therefore, this study tested the possible increase in gray matter (GM) volume in the RSC/PCC and PHC in the brains of a worlds top blind soccer player and other blind soccer players. We collected structural magnetic resonance imaging (MRI) scans from six blind soccer players (including the worlds top player) and eight blind non-soccer players. Using voxel-based morphometry (VBM) analysis (single-case VBM approach), we examined GM volume increase in each participant compared to 250 sighted participants (all of whom had never played blind soccer). Compared with the sighted participants, the worlds top blind soccer player had a significant increase in GM volume in the bilateral RSC/PCC. Two of the other five blind soccer players also showed an increase in the left RSC/PCC. However, such an increase in GM volume was not observed in the blind non-soccer players. Eventually, the probability of a significant increase in the RSC/PCC was significantly higher in the blind soccer group than in the blind non-soccer group. In contrast, only one blind soccer player (not the top player) showed a significant increase in the PHC, and no between-group difference was observed in the probability of a significant increase in the PHC. This study, unveiling the characteristics of the brains of the worlds top blind soccer player and of other blind soccer players, for the first time demonstrates that blind soccer training, which requires spatial navigation based on non-visual cues, may enlarge the human RSC/PCC and provide findings that promote understanding the brains of challenged persons playing blind soccer.