Examining Variability of High-Level Visual Categories Across Development

There exist numerous high-level category-selective areas within ventral temporal cortex (VTC), including the word-selective visual word form area (VWFA), face-selective fusiform face area (FFA), and object-selective posterior fusiform sulcus (PFS). Although the existence and functions of these areas have been thoroughly investigated, it remains unclear whether these regions vary more in their selectivity and spatial location or extent in childhood, and how this variability changes across development. Here, using a sample of 42 children, some scanned across multiple timepoints, we attempt to answer this question. We scanned children ages 3-9 on a functional MRI experiment where they saw line drawings of faces, words, scrambled words, and everyday objects. We defined bilateral VWFA, FFA, and PFS fROIs in each participant and calculated selectivity to the preferred category in independent fMRI runs. Children were divided based on age (below or above 6) and matched based on motion on the task. We calculated variability across children by computing distance of each child’s selectivity and center of gravity (in fROIs projected to template space) to each other child in their age-group, and also coefficient of variation (CV) of the standard deviation of this distance divided by mean distance. We find that while selectivity increases with age for many fROIs, as reported previously, distance and CV of selectivity are relatively stable with age; center of gravity was more variable in older children for all fROIs. Ongoing investigations include comparisons of spatial location (with respect to anatomical landmarks) of these fROIs across development, as well as comparisons to a motion-matched adult sample to further test the theory that variability increases with greater experience.