VISUAL CORTICAL AREA MT IS REQUIRED FOR DEVELOPMENT OF THE DORSAL STREAM AND ASSOCIATED VISUOMOTOR BEHAVIOURS

The middle temporal (MT) area of the extrastriate visual cortex has long been studied in adulthood for its distinctive physiological properties and function as a part of the dorsal stream. More recently, developmental studies have concluded that its maturation is temporally in parallel with the primary visual cortex (V1). Here we examined whether an early-life lesion of MT altered the normal anatomical and physiological development of dorsal stream areas and the behavioural precision of adult reaching to grasp sequences. We observed permanent changes in the anatomy of cortical areas associated with both reaching (PE and MIP) and grasping (AIP), as well as in reaching and grasping behaviours. In addition, we observed a significant impact on the anatomy of V1 and the direction sensitivity of V1 neurons in the lesion projection zone. These findings indicate that area MT is a crucial node for the development of the primate vision, impacting both V1 and areas in the dorsal visual pathway known to mediate visually guided manual behaviours.