Santani Teng - US grants

PROJECT SUMMARY For the 40 million people worldwide who are blind, everyday activities like navigating a room, identifying a building, or catching a bus present major challenges, especially in unfamiliar areas. Some blind individuals augment their perception to a remarkable degree via active echolocation, producing a ?click? sound with their tongues to perceive the object and spatial data encoded in the returning echoes. Echolocation is a useful perceptual and mobility aid for blind persons and a unique scientific model to studying fundamental neural and perceptual mechanisms. Yet it remains incompletely understood, understudied, and thus rarely taught, rendering it inaccessible to the majority of untrained people who are blind or visually impaired. The goal of the proposed research is to characterize the neural dynamics underlying active echolocation. It is a unique sensing modality that consistently activates various occipital ?visual? cortical regions in blind echolocators, but the dynamics of that brain activity, and its relationship to active click production, is poorly understood. Here we propose to leverage the fine-grained temporal resolution of magnetoencephalography (MEG) to trace the dynamics of echolocation processing and to determine the roles and processing circuits for active echolocation signals. We will recruit blind and sighted participants and record MEG as they listen to echo stimuli and actively ensonify virtual reflecting objects in the scanner. We will use these data to propose a model of echolocation incorporating the active click production, sensory feedback from the echoes, and relevance to a behavioral goal. The results will inform theories of active perception, which currently lack well defined models in audition; neuroplasticity in blindness, which underrepresents temporal dynamics; and eventually orientation and mobility training, which lacks evidence to motivate echolocation-based interventions. Methodologically, in performing the proposed work, we will pioneer temporally resolved neuroscience of echolocation, expand the application of artifact-reduction algorithms, and introduce a novel framework for studying auditory sensory-motor coupling paradigms.