ABSTRACT

Acknowledgment 193

References 193

11.1 INTRODUCTION

This chapter is focused on models of the primate saccadic system that attempt to explain the role played by superior colliculus (SC) in the generation of these specialized eye movements. In particular, it concentrates on reviewing more recent attempts to include a distributed representation of the operation of the deeper layers of the SC and their role in saccade generation, in contrast to earlier models, which used lumped systems representations of the colliculus that provided a single output signal from the SC to the brainstem saccadic burst generator. In the context of the present chapter, distributed representations are those that represent the SC as a dynamic network that processes visuomotor information with a spatial grid of neuron-like elements interconnected with excitatory and inhibitory connections. Lumped representations use single-input/single-output, dynamic engineering elements to represent signal processing in the SC. The chapter begins with a brief

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summary of relevant anatomical and physiological data on the SC that the new distributed models attempt to encapsulate. A further brief summary reviews work that has made estimates of the spatiotemporal population discharge in the SC during saccades. Knowledge of this population activity is a crucial guide to the development of distributed models with biological realism. New experimental results that need to be incorporated in distributed models are also discussed.