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Neuro-Ophthalmology - part 9

Chương này cung cấp cho một tổng quan về các mô hình hiện tại của hệ thống động cơ mắt. Bắt đầu với mô hình của con đường mắt cuối cùng bao gồm các nhà máy mắt và tích hợp tốc độ, vị trí thần kinh để giữ cái nhìn, các mô hình của phần động cơ của hệ thống saccadic | Straube A Bũttner U eds Neuro-Ophthalmology. Dev Ophthalmol. Basel Karger 2007 vol 40 pp 158-174 Current Models of the Ocular Motor System Stefan Glasauer Center for Sensorimotor Research Department of Neurology Ludwig-Maximilian University Munich Munich Germany Abstract This chapter gives a brief overview of current models of the ocular motor system. Beginning with models of the final ocular pathway consisting of eye plant and the neural velocity-to-position integrator for gaze holding models of the motor part of the saccadic system models of the vestibulo-ocular reflexes VORs and of the smooth pursuit system are reviewed. As an example a simple model of the 3-D VOR is developed which shows why the eyes rotate around head-fixed axes during rapid VOR responses such as head impulses but follow a compromise between head-fixed axes and Listing s law for slow VOR responses. Copyright 2007 S. Karger AG Basel The ocular motor system is one of the best examined motor systems. Not only are there numerous studies on behavioral data but also the neurophysiology and anatomy of the ocular motor system is well documented. This knowledge makes the ocular motor system a perfect candidate for modeling. Models of the ocular motor system span the range from models at the systems I eve 1 to detailed neural networks using firing rate neurons. Spiking neuron models are at present rare. The main reason is that the ocular motor system is composed of a wealth of neuronal structures which makes a detailed implementation using spiking neuron models computationally difficult. Moreover the impressive explanatory power of models at the systems level has not yet raised the need for more detailed modeling at the level of single neurons except for restricted subsets of the ocular motor circuitry. The present chapter attempts to give an overview of the most recent models related to the ocular motor system without trying to compile a complete bibliography or referring to the whole seminal work by .