“Neural control of disconjugate eye movements in the primate”

To orient our gaze between targets in a 3D-space, located in different directions and at different distances, we make eye movements with appropriate versional and vergence components where the left and right eyes move with unequal amplitudes. These disjunctive saccades are the most common eye movements generated to look at targets in a natural environment. However, the neural strategy used to execute these combined saccade-vergence eye movements is still poorly understood. Recent anatomical studies suggested that the central mesencephalic reticular formation (cMRF) contains premotor neurons potentially involved in the control of these disjunctive eye movements. My talk will focus on the result of our neural recording experiments in the cMRF in awake and trained monkeys. I will describe a unique population of neurons called saccade-vergence burst neurons which discharge a burst of action potentials only when the animal performs a disjunctive saccade. This neuronal population is the first to demonstrate specific involvement in the generation of the disjunctive saccades required to view objects in the 3D world. It also provides a critical basis for understanding the absence of precise binocular coordination in eye movement dysfunctions such as strabismus.