Visual BOLD Response in Late Blind Subjects with Argus II Retinal Prosthesis

• Published in: PLoS biology Vol. 14; no. 10; p. e1002569
• Main Authors: Castaldi, E., Cicchini, G. M., Cinelli, L., Biagi, L., Rizzo, S., Morrone, M. C.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.10.2016; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Blindness - diagnostic imaging; Blindness - etiology; Blindness - physiopathology; Brain research; Clinical trials; Colleges & universities; Eyes, Artificial; Funding; Geniculate Bodies - physiopathology; Humans; Localization; Magnetic Resonance Imaging; Medicine and Health Sciences; Oxygenation; Patients; Properties; Prostheses; Research and Analysis Methods; Retina; Retinitis Pigmentosa - complications; Social Sciences; Surgery; Transplants & implants; Visual Acuity; Visual Prosthesis
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.1002569

Retinal prosthesis technologies require that the visual system downstream of the retinal circuitry be capable of transmitting and elaborating visual signals. We studied the capability of plastic remodeling in late blind subjects implanted with the Argus II Retinal Prosthesis with psychophysics and functional MRI (fMRI). After surgery, six out of seven retinitis pigmentosa (RP) blind subjects were able to detect high-contrast stimuli using the prosthetic implant. However, direction discrimination to contrast modulated stimuli remained at chance level in all of them. No subject showed any improvement of contrast sensitivity in either eye when not using the Argus II. Before the implant, the Blood Oxygenation Level Dependent (BOLD) activity in V1 and the lateral geniculate nucleus (LGN) was very weak or absent. Surprisingly, after prolonged use of Argus II, BOLD responses to visual input were enhanced. This is, to our knowledge, the first study tracking the neural changes of visual areas in patients after retinal implant, revealing a capacity to respond to restored visual input even after years of deprivation.