November 11, 2020

University of Alabama at Birmingham (UAB) researchers have discovered a previously undescribed population of neurons that help control our eyes as they view in three-dimensional space.

During normal viewing, we direct our eyes between objects in the three-dimensional space many times a minute. With each change, the left and right eyes will rotate, generally in the same direction, but mostly by different degrees of rotation. These unequal movements are known as disjunctive saccades.

Several models of eye movement predicted the existence of a population of neurons called saccade-vergence burst neurons, or SVBNs, that would produce a burst of activity solely during disjunctive saccades, while not firing during the other two types of eye movements. 

The results of this study and previous studies elsewhere and at UAB suggest that SVBNs could play a role in all the components of the near triad responses — lens accommodation, pupillary constriction and vergence.