Distributed model of control of saccades by superior colliculus and cerebellum.

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.