Kahler, L. | Search bioRxiv

bioRxiv2026

Sign language communication enhances representations for hands in high-level visual cortex

High-level visual cortex supports the perception and recognition of visual categories. What is the role of experience in shaping this region and the time course over which it stays malleable? We tested whether experience with a sign language, where information is conveyed via the hands and face, shapes category representations in high-level visual cortex. We acquired functional MRI data from 20 hearing signers and 20 non-signers while they viewed images from ten categories, including faces and hands. We compared the neural distinctiveness and size of category-selective regions between groups in ventral temporal and lateral occipito-temporal cortex. Signers showed higher distinctiveness for hands and larger hand-selective regions than non-signers in the left hemisphere, and sign language experience predicted neural hand representations. Critically, ventral hand representations were also enhanced in signers who learned sign language in adulthood. These findings indicate that visual cortex retains experience-dependent plasticity into adulthood, with implications for visual learning and cortical development.

neuroscience↗

bioRxiv2026

Limb-Selective Regions in the Lateral Temporal Lobe Shrink from Childhood to Adulthood

Perceiving hand gestures and inferring others actions and emotions from movements of hands and limbs play an important role in every-day interactions, especially in young children. The perception of categories such as limbs, bodies, or faces is supported by category-selective regions in the temporal lobe. Some category-selective regions, such as those reacting selectively to body parts or limbs, exist both on the ventral and on the lateral side of the temporal lobe, and are part of the ventral and lateral stream, respectively. While it was recently shown that limb-selective regions in the ventral stream shrink from childhood to adulthood, the developmental trajectory of limb-selective regions in the lateral stream remains unknown. To close this gap in knowledge, we acquired functional magnetic resonance imaging (fMRI) data in 21 children aged 10 - 12 years and 20 adults while they watched images of 10 visual categories including limbs and whole bodies. We first replicate the decrease of limb-selectivity from childhood to adulthood in the ventral temporal lobe. Across several analyses, our results further demonstrate that limb-selective regions in the lateral temporal lobe shrink as well, particularly in the left hemisphere. Underlining the specificity of our finding, we show that lateral body-selective regions show no significant development from childhood to adulthood. These findings advance our understanding of the developmental trajectories of limb- and body-selective regions and of the ventral and lateral visual streams more broadly.

neuroscience↗