A Developmental Model of Hemispheric Asymmetries of Spatial Frequencies

Lateralization touches virtually every function we think makes us human and interacts fundamentally with development. Here we connect lateralized function to anatomical asymmetries, and connect those anatomical asymmetries to temporal asymmetries in development. Our differential encoding (DE) model (Cipollini, Hsiao, & Cottrell, 2012; Hsiao, Cipollini, & Cottrell, 2013; Hsiao, Shahbazi, & Cottrell, 2008) suggests that lateralization in visual processing of spatial frequencies is the result of a postulated asymmetry in the spatial spread of connections within retinotopic visual cortex. We present three new results with the model. First, previous versions were trained only on the images used in behavioral experiments; here we show that the behavioral results persist when our model is trained on natural images, warped to match physical distortions of V1. Second, we show that the anatomical asymmetry can result from 1) the known temporal asymmetry in developmental pruning, coupled with 2) known acuity changes, which result in the two hemispheres being trained with images of different spatial frequency content. Third, the developmental model results suggest that the LH is not specialized for HSF processing; rather, the RH is specialized for LSF processing to the detriment of HSF processing.