Studies of both animals and humans have suggested that these smaller commissures play a role in interhemispheric hippocampal connectivity due to their proximity to the hippocampus.49,53,54 Our data show interheimspheric connectivity occurs near both the anterior and posterior commissures among healthy brains. In contrast, interhemispheric connectivity among injured brains occurs more posteriorly, and may rely on posterior commissural fibers (i.e., posterior commissure and/or dorsal hippocampal commissure) to a greater degree than healthy brains. Additionally, patients demonstrated more diffuse but weaker correlations throughout the medial temporal and frontal lobes, and posterior cingulate cortex as compared to controls. This appears to be evidence of neural inefficiency, and may represent the brain’s attempt to restore interhemispheric hippocampal connectivity by utilizing less direct connections in light of injured subcortical white matter.
