Magnocellular and parvocellular visual pathways, involvement in reading. Examination of developmental trajectories, visual cortex regions and reading circuitries

Abstract

The magnocellular and parvocellular systems are major visual recognition pathways, with distinct histological and physiological properties. Despite their critical role, there is limited evidence on the specific contributions of these visual pathways to visual recognition in general, word reading in particular, as well as in regard to their developmental trajectories. This doctoral dissertation is aimed at examining the involvement of the magnocellular and parvocellular pathways in reading over development (Empirical Part I), in visual cortex regions during reading and visual recognition (Empirical Part II) and in the two main reading ventral and dorsal networks (Empirical Part III). Our results revealed i) a more protracted maturation of the magnocellular visual pathway compared to the magnocellular pathway from middle childhood to adulthood, ii) a functional division of labor in the visual cortex as a function of the parvocellular and magnocellular properties of the stimuli, and iii) that both the magnocellular and parvocellular pathways are involved in reading processes, with the parvocellular pathway mainly contributing to the ventral reading network and the magnocellular pathway mainly contributing to the dorsal reading network.