The Path of Conscious Perception: Decoding Phosphene Perception after Intracortical Microstimulation

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Cortical visual prosthetics are a promising solution to restoring a form of vision for some blind individuals. However, the relation between stimulation, neural response and phenomenological experience is not entirely clear: identical stimulation patterns can sometimes elicit phosphenes, while at other times no percept is induced. In this report, a first step is made towards unravelling the neural dynamics that occur in response to cortical microstimulation and their connection to the perception of phosphenes. Using machine learning techniques, the data available from extensive experiments with a blind volunteer, collected at the University Miguel Hernández, are used to predict the perception of phosphenes. Results show that all three investigated neural data signals (MUA, LFP and EEG) contain markers of the perceptual outcome, as our models were able to classify this outcome at above-chance level. Further insight was obtained regarding the spatial, temporal and frequency characteristics of these signals. In particular, our results align with previous findings that signal loss occurs at different stages along the propagation of the signal from the occipital pole to the frontal areas, as well as the existence of a feedback signal.
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