Amy Poole¹, Kelly Chang², Feiyi Wang³, Ione Fine², Woon Ju Park⁴; ¹University of Minnesota, ²University of Washington, ³Boston University, ⁴Georgia Institute of Technology

Early blindness results in dramatic changes in the structure and function of the primary visual cortex. Here, we examined the structural plasticity in the auditory cortex, specifically the Heschl’s gyrus (HG). Previous work shows increased HG folding in professional musicians than non-musicians, suggesting a possibility that extensive auditory experience resulting from visual loss might alter HG structure in blind individuals. We analyzed T1-weighted images collected from previous MRI studies at the University of Washington (Jiang et al., 2016; unpublished data), University of Pennsylvania, and Oxford University (Aguirre et al., 2016; Bridge et al., 2009). The combined dataset included 6 anophthalmia (individuals born without eyes), 48 early blind, 18 late blind, and 28 sighted control participants. Hand-drawn HG regions of interest for each participant in both hemispheres were created. HG is known to show high morphological variability across individuals. We characterized HG structure by 1) visually categorizing HG morphology (single, partial, or complete duplication of the gyrus) and 2) using continuous metrics including curvedness index, gyrification index, thickness, gray matter volume, and surface area. In contrast to the deprived primary visual cortex, the structure of HG was not altered by blindness. A chi-squared test revealed that the HG morphology was not significantly different across the four groups. Linear mixed-effects models (controlling for age, hemisphere, and scan location) similarly showed no effects of group on the gyrification index, curvedness index, thickness, gray matter volume, and surface area. Our findings suggest that visual loss does not alter the structure of the non-deprived auditory cortex. Structural plasticity following blindness might be limited to the occipital cortex, challenging the idea that extensive experience can shape the anatomical properties of primary sensory cortices. The results in musicians likely reflect a selection bias, where individuals with increased HG folding are more likely to become musicians.

Acknowledgements: NEI R00 EY034546 to WP; NEI R01 EY014645 to IF