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According to Casteau and Vitu, a fixation population, if it exists, is probably located not in the SC but in the brainstem omnipause region.

According to Casteau and Vitu, a fixation population, if it exists, is probably located not in the SC but in the brainstem omnipause region.

Omnipause neurons (OPN) receive input from neurons across the SC, though more strongly from the rostral part.

Distractors close to a saccade target do not seem to affect saccade latency but change their landing sites.

Casteau and Vitu see the lack of a change in saccade latency due to distractors close to the saccade target as evidence against the lateral-inhibition theory of saccade generation.

Casteau and Vitu's results seem to show that it's not proximity between target and distractor but the ratio of their excentricities that saccade delay is dependent of.

The in-vitro study of the rat intermediate SC by Lee and Hall did not find evidence for the long-range inhibitory/short-range excitatory connection pattern theorized by proponents of the neural-field theory of SC fixation.

Currently, three types of saccade-related neurons are distinguished in the deep SC:

  • Burst- and build-up neurons on the one hand,
  • fixation neurons on the other.

There are neurons in the supplementary eye field which are related to

  • eye movements,
  • arm movements,
  • ear movements,
  • spatial attention.

People fixate on different parts of an image depending on the questions they are asked or task they are trying to accomplish.

Brouwer et al found that their subjects looked more at the contact position of the index finger when they were told to grasp an object than when they were just to look at it.

Munoz and Everling assume that there are distinct populations of fixation and saccade neurons in the SC and FEF.

In a more recent paper, Casteau and Vitu state that there is some debate about that. However, they, too argue for distinct fixation neurons. On the other hand, they also state that fixation neurons probably are not located in the SC itself, which is in contrast of what Munoz and Everling write.