[Synkinesis of head and eye movements evoked by brainstem stimulation in the alert monkey]

The synkinesis of head and eye movements evoked by electrical stimulation of the tectum and tegmentum in the alert monkey is described. In positions where both head and eye movements can be evoked, the two are almost always parallel in direction and they are superimposed on rather than substituted for each other. The directiion of movement depends on the stimulated positions: tilt and turn reactions are distributed according to laterality, direction of vertical movements depends more on the stimulus parameter than the electrode position. Head movements release vestibulo-ocular reflexes, which are superimposed on the electrically evoked eye movements.