Parallel Processing in a Neural Network

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PARALLEL PROCESSING IN A NEURAL NETWORK The goal of the proposed research is to gain further insight into mechanisms of parallel processing in the nervous system. Research will focus on the vestibulo-ocular reflex (VOR), which stabilizes vision by producing eye rotations that counterbalance head rotations. The VOR is mediated by vestibular nuclei neurons (VNNs). Recent neural network models suggest that the distributed encoding of eye-movement commands VNNs results because VNNs operate in parallel. The underlying assumption is that parallelism is critical to VOR function. The primary aim of the project is to quantitatively test this assumption by studying the effects on VOR of lesioning varying numbers of VNNs. Experimental subjects will be goldfish because they have a suitably well-developed VOR. To generate predictions, varying numbers of VNNs will be removed from a highly parallel and realistic model of the goldfish VOR. The initial prediction is that VNN lesions should degrade VOR function by increasing VOR harmonic distortion. This will be tested experimentally by comparing VOR eye-movements before and after VNN lesions. Data will be quantified using eye-velocity power spectra. Lesion size will be quantified histologically. Results will be incorporated into larger and more realistic VOR neural network models, which will be implemented on massively parallel computers. //