Functional and anatomical changes in high-level visual cortex during reading acquisition
Human Cognitive and Systems Neuroscience
Final Report Abstract
Human ventral temporal cortex (VTC) contains regions that respond preferentially to ecologicallyrelevant categories such as faces, bodies, places, and words. These regions are causally involved in the perception of these categories and are thus critical for human behavior. However, these regions are not yet mature during childhood. While some categories such as faces or bodies are seen from early in life, extensive experience with written words typically begins only when children enter school and learn how to read. So, how do these regions develop during childhood? In particular, does the emerging word-selective region develop upon raw, general-purpose cortex or on cortex that was previously selective to another category earlier in childhood? Here, we addressed these questions using longitudinal functional magnetic resonance imaging (fMRI) in school-age children. During fMRI children viewed images of 10 ecologically relevant categories including faces (adult faces, child faces), characters (words, numbers), bodies (headless bodies, limbs), objects (cars, string instruments) and places (houses, corridors). We analyzed data of 128 functional sessions from 29 children, who were initially 5-12 years old. Each child participated in multiple fMRI sessions over the course of several years enabling us to track individual development over a large time span during childhood. Results of this project revealed two key findings. First, our longitudinal measurements showed that while face- and word-selective regions increased during childhood development in line with previous findings, limb-selective regions shrank during childhood development and lost their selectivity to limbs. This surprising finding opens up new questions for future research. Second, our results showed that in the emerging parts of word- and face-selective regions, initial selectivity to limbs was repurposed into selectivity to words and faces, respectively. Thus, these results show that emerging category representations do not develop upon raw general-purpose cortex but provide evidence for cortical recycling in high-level visual regions during childhood, where limb-selectivity is recycled into word- and face-selectivity. These results are important because they reveal new insights about the functional development of high-level regions in visual cortex. First, they advance key theories about high level visual cortex development. Second, they have implications for understanding both typical and atypical development, as they fill a gap in knowledge by quantifying the rate of the development of category-selectivity in VTC. As such, they offer a foundation for using fMRI to assess developmental and learning deficiencies related to reading and social perception.
Publications
- (2020) Selectivity to limbs in ventral temporal cortex decreases during childhood as selectivity to faces and words increases. Vision Sciences Society Annual Meeting Abstract. Journal of Vision. Abstract issue 2020
Nordt, M., Gomez, J., Natu, V., Rezai, A.A., Finzi, D., Kular, H., & Grill-Spector, K.
(See online at https://doi.org/10.1167/jov.20.11.152) - Cortical recycling in high-level visual cortex during childhood development. (accepted for publication at Nature Human Behaviour)
Nordt, M., Gomez, J., Natu, V., Rezai, A.A., Finzi, D., Kular, H., & Grill-Spector, K.
(See online at https://doi.org/10.1101/2020.07.18.209783 http://dx.doi.org/10.1038/s41562-021-01141-5) - Differential spatial computations in ventral and lateral face-selective regions is scaffolded by structural connections. Nature communications
Finzi, D., Gomez, J., Nordt, M., Rezai, A.A., Poltoratski, S., & Grill-Spector, K.
(See online at https://doi.org/10.1101/2020.07.06.190371 http://dx.doi.org/10.1038/s41467-021-22524-2)
