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Shir Hofstetter, Wietske Zuiderbaan, Serge Dumoulin, Amir Amedi; The mapping and reconstruction of the brain's mind eye in the absence of visual experience: a population receptive field mapping of soundscape space. Journal of Vision 2018;18(10):1228. doi: https://doi.org/10.1167/18.10.1228.
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Studies showed that blind participants trained in visual-to-auditory sensory substitution devices (SSDs) were able to recognize various 'visual' objects and even body shapes and faces. Correspondingly they also specifically activated many of the known categories in the high-order visual streams1. But how is this learned experience integrated in the brain? Does the visual-to-auditory input follow similar organizational principles as the natural senses? Here we studied a proficient EyEMusic-SSD2 congenitally blind user using population receptive field (pRF) mapping3, a method for imaging visual retinotopic maps. The EyEMusic-SSD algorithm reads the image from left to right and forms a soundscape of the image where the X and Y axes are represented by time and pitch in pentatonic-scale, respectively2. Full tonotopic maps of musical pitch-elevation (y axis) were found in bilateral A1, showing organized maps of the EyeMusic's notes. Moreover, topographical maps of the soundscape field were found in the right lateral occipital (LO), right medial occipital cortex, and right parietal-occipital cortex (PO). Full topographic maps of timing of the stimuli (x axis) were shown in the same regions in the right LO and right PO. Notably, in the right PO, the maps of the two axes overlapped. Conceptually, this proposes that the learned soundscape field may be analyzed in a similar way to how the two dimensions of retinotopy, eccentricity and polar angle, span the visual field. We were also able to reconstruct and predict the perceived stimuli in the soundscape-field. This case study suggests that in adulthood novel topographic maps can develop following extensive training in novel topographic sensory experiences. References 1. Amedi, A. et al. Trends Cogn. Sci., 2017 2. Abboud, S. et al. Restor. Neurol. Neurosci. 2014 3. Dumoulin, S.O. et al. Neuroimage, 2008
Meeting abstract presented at VSS 2018
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