Visual Field Inhomogeneities Shape Visual Working Memory

Whether early visual cortex (V1) is essential for visual working memory (vWM) performance remains a topic of scientific debate. The current study aimed to expand previous research findings by examining whether idiosyncratic structural properties of V1, particularly visual field inhomogeneities such as visual field and polar angle asymmetries, are reflected in interindividual differences in vWM performance. A total of 292 participants underwent an MRI scan using a multiparametric mapping sequence, generating four quantitative microstructural maps per participant: magnetization transfer (MT), proton density (PD), longitudinal relaxation rate (R1), and transverse relaxation rate (R2*). In a separate session, the participants completed a vWM task designed to probe visual field inhomogeneities. Behavioral results are consistent with previously reported asymmetries in vWM, particularly the inverted polarity of the vertical meridian asymmetry (VMA). Quantitative MRI analysis revealed associations between VMA and multiple qMRI parameters in V1, indicating that individual differences in V1 architecture contribute to variability in vWM performance. Additionally, cortical thickness measures revealed a link between V3 and left-right asymmetry, suggesting that structural variability beyond V1 also shapes vWM performance. These findings are consistent with the sensory recruitment hypothesis and suggest that structural characteristics of early visual areas influence vWM performance.