Modelling the role of the cerebellar fastigial nuclei in producing accurate saccades: the importance of burst timing

doi:10.1016/0306-4522(95)00239-F

Neuroscience

Volume 68, Issue 4, October 1995, Pages 1059-1077

https://doi.org/10.1016/0306-4522(95)00239-F Get rights and content

Abstract

Clinical and experimental data indicate that damage to the cerebellar vermis results in permanent loss of saccadic accuracy. Models of saccade production therefore need to provide a role for the cerebellum. It has been proposed that the vermis adjusts the gain of the saccadic internal feedback loop in response to information about the amplitude of the intended saccade. A model of how the fastigial nuclei (through which vermal output is channelled) influence brainstem saccadic circuitry to achieve this effect was constructed in three stages. (1) The brainstem was represented by a version of Robinson's internal feedback model, which relates excitatory burst neuron discharge to horizontal saccade dynamics. (2) The original model was lesioned to simulate the effects of bilateral inactivation of the fastigial nuclei, namely slow hypermetric saccades. This required reducing the synaptic weight of the internal feedback pathway, and lowering the gain of the excitatory burst neurons. The resultant brainstem-only model served as a preparation for testing the effects of neuronal discharge patterns within the fastigial nuclei. (3) These discharge patterns were simulated using measurements from recent electrophysiological studies.

It was found that saccadic accuracy and normal dynamics were restored in the model if the simulated burst from neurons in the contralateral fastigial nucleus were subtracted from the feedback signal (i.e. added to the command signal) early in the saccade, and the burst from neurons in the ipsilateral fastigial nucleus were added to the feedback signal later in the saccade. This pattern corresponds to the observed timing of neuronal bursts in the fastigial nuclei, and accounts qualitatively for the effects of unilateral stimulation and inactivation of both the fastigial nuclei and the cerebellar vermis.

This method of producing accurate saccades also contributes to time optimal control, by increasing both saccadic acceleration and deceleration. Appropriate timing of burst onset and duration in the fastigial nuclei is essential for these roles. Evidence concerning the effects of cerebellar damage on fast movements of other parts of the body suggests that the cerebellum may use similar strategies for controlling a wide range of simple movements.

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Research paperModelling the role of the cerebellar fastigial nuclei in producing accurate saccades: the importance of burst timing

Abstract

Expl Neurol.

Neur. Networks

Brain Res.

Vis. Res.

Vis. Res.

Curr. Opin. Neurobiol.

Prog. Neurobiol.

Neuroscience

Expl Neurol.

Neurosci. Res.

Neurosci. Res.

Neurosci. Res.

Neurosci. Res.

Vis. Res.

Prog. Neurobiol.

Neurosci. Res.

Neurosci. Res.

Curr. Opin. Neurobiol.

Brain Res.

Neural Networks

Vis. Res.

Vis. Res.

Primate frontal eye fields; I. Single neurons discharging before saccades

J. Neurophysiol.

The reticular formation

Eye Movements

Vision and Visual Dysfunction

Time optimal behavior of human saccadic eye movement

IEEE Trans. Autom. Contr.

Fastigial evoked eye movement and brain stem neuronal behavior in the alert monkey

Acta Oto-Laryngologica

Binocular co-ordination of human horizontal saccadic eye movements

J. Physiol.

The human oculomotor control system

A model for the sensorimotor transformations required for accurate 3-D saccades

Soc. Neurosci. Abstr.

Learning and maintaining saccadic accuracy: a model of brainstem-cerebellar interaction

J. cog. Neurosci.

Adaptive gain control of saccadic eye movements

H. Neurobiol.

The initial direction and landing position of saccades

Movement and electromyographic disorders associated with cerebellar dysmetria

J. Neurophys.

Saccadic and smooth pursuit eye movements in the monkey

J. Physiol.

Brainstem control of saccadic eye movements

A. Rev. Neurosci.

Discharge of simian caudal fastigial nucleus neurons during smooth-pursuit eye movements

DAR Festschrift

Role of the caudal fastigial nucleus in saccade generation. I. Neuronal discharge patterns

J. Neurophys.

The role of the cerebellum in the control of saccadic eye movements

Afferents of the caudal fastigial nucleus in a New world monkey (Cebus apella)

Expl Brain Res.

Origin of cerebellar projections to the region of the oculomotor complex, medial pontine reticular formation, and superior colliculus in New World monkeys: a retrograde horseradish peroxidase study

J. comp. Neurol.

Neural Dynamics of Adaptive Sensory-Motor Control

Physiological analysis of simple rapid movements in patients with cerebellar deficits

J. Neurol. Neurosurg. Psychiat.

Cerebellar dynamics: the mossy fiber input

IEEE Trans. biomed. Eng.

Research paper
Modelling the role of the cerebellar fastigial nuclei in producing accurate saccades: the importance of burst timing