Blindness reveals that Heschl's gyrus folding is not altered by auditory experience.

Heschl's gyrus (HG), which contains the primary auditory cortex, shows marked individual variability in its folding pattern, ranging from a single gyrus to partial or complete duplication. Greater HG duplication has been reported in expert musicians, often interpreted as evidence that auditory experience can shape cortical morphology. However, these structural differences might alternatively indicate a bias for musical careers in individuals whose anatomical predispositions facilitate expertise. Here, we examined HG morphology in blind individuals-a population with extensive auditory experience but without selection based on auditory ability. T1-weighted MRI data from 100 human participants (48 females, 42 males, 10 unknown) across blind and sighted groups were analyzed. HG was manually defined in each hemisphere, and folding was measured using both categorical morphology classification and continuous surface-based metrics. Across all analyses, blindness did not increase HG folding. These results suggest that the morphology of HG is largely predetermined.