Abstract
<title>Abstract</title> <p>The hippocampus is a complex structure with distinct subfields that support learning and memory, including the formation of cognitive maps for spatial navigation. In humans, this process relies heavily on visual information and is significantly affected by blindness. However, few studies have examined blindness-related neuroplastic changes in the hippocampus, particularly the role of hippocampal subfields in non-visual cognitive maps. We used T1-based MRIs from 14 early blind (EB), 14 late blind (LB), and 19 sighted controls (SC) to segment the hippocampus into three subdivisions (CA1, DG/CA3, and subiculum). We then examined the relationship between subfield volumes and performance on a “spatial learning” task assessing non-visual, cognitive map-based navigation. Although there were no overall volumetric differences across groups, DG/CA3 volumes correlated with navigation performance in EB, and subicular (and presubicular) volumes correlated with both navigation performance and learning rates in EB and LB. No correlations were found in SC. Taken together, these findings suggest that hippocampal output pathways (subiculum), head-direction coding (presubiculum), and pattern separation/completion processes (DG/CA3) may play important roles in cognitive mapping in blindness. They further indicate that the neural foundations of allocentric spatial coding are preserved in EB individuals, and that variability in cognitive mapping abilities among EB and LB may arise not only from the formation of hippocampal spatial codes but also from how these representations are distributed and integrated with egocentric representations beyond the hippocampus.</p>