Janette Atkinson
University College London, UK
Title: Cerebral visual impairment: dorsal stream vulnerability from amblyopia and autism to attention
Biography
Biography: Janette Atkinson
Abstract
Advances in assessing sensory and cognitive vision in infants and young children have enabled us to establish milestones of visual development and provide means for identifying visual disorders at an early age. These include novel EEG and behavioural techniques and tests such as Cambridge Crowding cards, the first child-friendly preschool crowded acuity test for identifying amblyopia, and photo- and video refraction (VPR1), for rapid identification of refractive errors at any age. Using these new techniques, in our population RCT refractive screening programs of over 8000 infants, we demonstrated that refractive correction with glasses in infancy could successfully reduce the incidence of strabismus and amblyopia. However, many children who had been significantly hyperopic in infancy showed mild pre-school visuomotor and attentional deficits. Combined with similar deficits in neurodevelopmental disorders, this led us to devise measures of development of the cortical dorsal stream, underpinning motion sensitivity, visuomotor control of actions and eye movements, and the ventral stream, underpinning orientation, shape, and object/face perception. The ball in the grass test compares motion sensitivity (dorsal) with static form sensitivity (ventral). We found deficits in motion sensitivity in children with Williams syndrome, autism, very preterm birth, perinatal brain injury and hemiplegia. This dorsal stream vulnerability (DSV) has now been found in many disorders, both genetic and acquired, including amblyopia. Besides poor motion sensitivity, it includes deficits in visuomotor control and visual attention. From MRI, we find that children’s individual differences in motion sensitivity are correlated with specific areas of growth in parietal cortex, the integrity of the superior longitudinal fasciculus (major fibre tract connecting frontal with parietal areas) and visuomotor and mathematical ability. This suggests that motion sensitivity relates to higher-order decision-making and visual attention, and may provide useful early diagnostic indicators of visuo-cognitive deficits in amblyopia, cerebral visual impairment and genetic retinal dystrophies.