Abstract
Pause neurons (PNs) are inhibitory neurons in the medial pontine reticular forma-tion which fire tonically and cease firing about 20 ms prior to quick eye movements in all directions. Anatomical and physiological evidence from cats has shown that these neurons (1) project and terminate on two groups of burst neurons involved in the genesis of horizontal saccadic eye movements: inhibitory burst neurons (IBNs) and excitatory burst neurons (EBNs), (2) project to the caudomedial subthalamus: the nucleus of the Field of Forel containing burst neurons which relate to vertical eye movement, (3) project to other reticular formation neurons from the midbrain to medulla, and (4) project to the upper cervical cord. PNs play an important role in the quick eye movement aspect of gaze control; and may also play a role in quick head movements which are related to gaze control.
This paper mainly describes anatomical evidence of the trajectory of single PNs and the projection of PNs to various eye movement-related areas in the brain stem, using intra-axonal staining with horseradish peroxidase and micro-injection of the tracer Phaseolus vulgaris leucoagglutinin.
