Abstract
Computations performed by a given cortical region are a product of its underlying cytoarchitecture and likely sculpted through development. Novel quantitative magnetic resonance imaging (qMRI) methods sensitive to such cortical properties (e.g. macromolecular tissue volume "MTV", and tissue composition measured through T1 relaxation time "T1r") allow us to explore the developmental interplay between neural structure, function, and behavior. Its anatomical consistency and prolonged development make human ventral temporal cortex (VTC) an ideal test bed to establish a fundamental and novel relationship within the nervous system: how anatomical changes in gray matter tissue relate to changes in function and ultimately behavior across development. Combining functional and quantitative MRI with behavior, we investigated if the development of a region's functional selectivity, and subjects' visual recognition ability, are constrained by changes in the underlying gray matter of VTC. From childhood (n=22, 5-12yo) to adulthood (n=25, 22-28yo), we find face-selective cortex is characterized by decreasing T1r (increased MTV; Figure 1A) with correlated increases in functional selectivity (Figure 1B). In place-selective cortex, T1r and consequently selectivity do not develop. We demonstrate that recognition memory is correlated across development with tissue properties in face-selective cortex, with lower T1r (higher MTV) associated with improved recognition ability for faces, but not places (Figure 1B). In addition, we relate quantitative differences in macromolecular tissue properties between face- and place-selective cortex to ex vivo histology employing a novel ex-to-in vivo registration pipeline. We demonstrate that post mortem descriptions of cellular organization in two new cytoarchitectonic regions in VTC mirror our in vivo measurements (Figure 1C). Lastly, while such cytoarchitectonic differences are measurable in our living adults, such differences have yet to emerge in childhood. Together, these data offer a novel behaviorally relevant model by which emergent functional properties shape, or are shaped by, structural development in human visual cortex.
Meeting abstract presented at VSS 2016