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Samantha Cunningham, Bosco Tjan, Pinglei Bao, Paulo Falabella, James Weiland; Tactile-Evoked V1 responses in Argus II Retinal Prosthesis Patients assessed with fMRI: A Case Study. Journal of Vision 2015;15(12):359. doi: https://doi.org/10.1167/15.12.359.
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© ARVO (1962-2015); The Authors (2016-present)
Neuroimaging studies demonstrate that vision loss in late-blind patients causes the primary visual cortex (V1) to respond to other sensory modalities. In a case-study, we characterized the effect of partial vision restoration with an electronic retinal prosthesis on cross-modal responses in V1. Following successful implantation with the Argus II epiretinal prosthetic system, two late-blind retinitis pigmentosa (RP) patients completed a series of MRI scans to determine: 1) the feasibility of acquiring images in the presence of the implant and 2) subjects’ BOLD response to three tactile tasks. Argus II subjects’ V1 tactile-evoked responses were acquired following counter-balanced periods of device use and no device use, and were further compared to the responses of 9 late-blind RP subjects and 9 sighted control subjects who previously completed the same tasks. Artifacts from the Argus II were limited to the orbit in which the device was implanted. No image distortion was evident in visual cortices for either structural or functional scans. For each subject and tactile task, the extent of the V1 tactile-evoked response increased following a period of not using their device. When compared to the 18 late-blind RP and sighted subjects, one Argus II subject who had been implanted for the shortest period of time (6 weeks) exhibited V1 tactile-evoked BOLD responses similar to RP subjects with only minimal light perception. The Argus II subject who had been implanted the longest (15 weeks) had a response extent similar to sighted control subjects and response strength similar to RP subjects with partial vision loss. Results from these two Argus II subjects indicate that long-term use of a retinal prosthesis may result in a reduction of tactile-evoked responses in V1. Our study also demonstrates that successful acquisition of structural and functional MR images is feasible in the presence of the electronic implant.
Meeting abstract presented at VSS 2015
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