Distributed model of control of saccades by superior colliculus and cerebellum

Università degli Studi di Trieste, Trst, Friuli Venezia Giulia, Italy
Neural networks: the official journal of the International Neural Network Society (Impact Factor: 2.08). 11/1998; 11(7-8):1175-1190. DOI: 10.1016/S0893-6080(98)00071-9
Source: PubMed

ABSTRACT We investigate the role that superior colliculus (SC) and cerebellum (CBLM) might play in controlling saccadic eye movements. Even though strong experimental evidence argues for an important role for the CBLM, the most recent models of the saccadic system have relied mostly on the SC for the dynamic control of saccades. In this study, we propose that saccades are controlled by two parallel pathways, one including the SC and the other including the CBLM. In this model, both SC and CBLM provide part of the drive to the saccade. Furthermore, the CBLM receives direct feedback from the brain stem and keeps track of the residual motor error, so that it can issue appropriate commands to compensate for incorrect heading and to end the movement when the target has been foveated. We present here a distributed model that produces realistic saccades and accounts for a great deal of neurophysiological data.

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    Edited by Koprinkova-Hristova, P. and Mladenov, V. and Kasabov, N. K., 01/2015: chapter Learning to look and looking to remember: a neural-dynamic embodied model for generation of saccadic gaze shifts and memory formation; Springer.
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    ABSTRACT: Fixational eye movements such as microsaccades are important to prevent fading. These miniature eye movements are also necessary to redirect gaze to the target after a drift. Generation of saccades and microsaccades utilizes common neural substrates. We, therefore, hypothesized that physiological modulators of saccades should also affect microsaccades. Test of this hypothesis will also provide support for the models of a microsaccade generation. We performed two experiments. In the first experiment, complete darkness led to a decrease in the frequency and velocity, but increased the amplitude of microsaccades. In the second experiment, active eyelid closure further reduced the velocity and frequency of microsaccades, but increased their amplitude. Darkness reduces the superior colliculus activity leading to a reduction in the velocity and frequency of microsaccades. Eye closure might cause sustained inhibition of the omnipause neurons. Subsequent disinhibition of the burst neurons might cause a reduction in the post-inhibitory rebound firing resulting in a decreased velocity of microsaccades. Sustained inhibition of the omnipause neurons could also reduce the inhibitory drive that would otherwise abort microsaccades. Hence, by inhibiting the activity of omnipause neurons, the eye closure could increase the amplitude of microsaccades.
    Experimental Brain Research 01/2015; 233(4). DOI:10.1007/s00221-014-4188-2 · 2.17 Impact Factor
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