Do you hear what I see? How do early blind individuals experience object motion?
Professor Ione Fine, University of Washington, USA
Perceiving object motion is fundamentally multisensory, yet little is known about similarities and differences in motion computations across different senses. Insight can be provided by examining auditory motion processing in early blind individuals. Early blindness leads to ‘recruitment’ of the ‘visual’ motion area hMT+ for auditory motion processing. Meanwhile, the planum temporale, associated with auditory motion in sighted individuals, shows reduced selectivity for auditory motion, suggesting competition between cortical areas for functional role.
According to the metamodal hypothesis of cross-modal plasticity developed by Pascual-Leone, the recruitment of hMT+ is driven by it being a metamodal structure containing “operators that execute a given function or computation regardless of sensory input modality”. According to the metamodal hypothesis, the computations underlying auditory motion processing in early blind individuals should be analogous to visual motion processing in sighted individuals – relying on non-separable spatiotemporal filters.
Inconsistent with the metamodal hypothesis, auditory motion filters, in both blind and sighted subjects, are separable in space and time. The computations underlying auditory motion processing in early blind individuals are not qualitatively altered; instead, the recruitment of hMT+ to extract motion information from auditory input includes significant modification of its normal computational operations.
The role of binocular vision in the development of visuomotor control and performance of fine motor skills
Dr Ewa Niechwiej-Szwedo, University of Waterloo, Canada
The ability to perform accurate, precise and temporally coordinated goal-directed actions is fundamentally important to activities of daily life, as well as skilled occupational and recreational performance. Vision provides a key sensory input for the normal development of visuomotor skills. Normal visual development is disrupted by amblyopia, a neurodevelopmental disorder characterized by impaired visual acuity in one eye and reduced binocularity, which affects 2–4% of children and adults. This presentation will discuss a growing body of research which demonstrates that binocular vision provides an important input for optimal development of the visuomotor system, specifically visually guided upper limb movements such as reaching and grasping. Research shows that decorrelated binocular experience is associated with both deficits and compensatory adaptations in visuomotor control. Parallel studies with typically developing children and visually normal adults provide converging evidence supporting the contribution of stereopsis to the control of grasping. Overall, this research advances our understanding about the role of binocular vision in the development and performance of visuomotor skills, which is the first step towards developing assessment tools and targeted rehabilitations for children with neurodevelopment disorders at risk of poor visuomotor outcomes.