Controversy on “Fixation Zone” of the Superior Colliculus

Abstract

The superior colliculus (SC) plays an important role in generating saccades. The rostral pole of the SC contains neurons whose discharge increases during visual fixation and decreases just before and during saccades, and is called the fixation zone. Fixation neurons are related to maintaining fixation and suppressing saccades. The more caudal SC contains saccade-related neurons that show burst activity at the onset of saccades, and is called the saccade zone. However, the functional independence of the rostral “fixation zone” is not necessarily accepted. This review will deal with controversies on the “fixation zone” of the rostral SC.

KEYWORDS:

• Superior colliculus
• fixation zone
• saccade
• omnipause neuron
• inhibitory burst neuron