Visually-triggered eye and head movements -gaze saccade- were simultaneously recorded in 12patients with posttraumatic cervical syndromes. In a great number of patients, the reaction time of gaze saccade increased markedly and the abnormality of visual fixation was induced after nuchal stimulation. A local infiltration in the cervical area with 1% procaine or an intravenous injection of centrophenoxine, made prior to the stimulation, no longer induced stimulating effects. On the other hand, there was almost no change in the velocity of the saccade and head turning either before or after cervical stimulation. The gaze saccade of a patient with a focal hemorrhage in the left superior colliculus had a longer latency. This increased latency was limited to the gaze saccade made on points in the contralateral visual field (contralateral to the lesion). There was no change in the velocity of the saccade and no longer deficit in the gaze accuracy. In a patient with a parietal lobe lesion due to a glioma, there was an increase in the latency to initiate the gaze saccade toward the contralateral side and a slight increase in the number of double saccades. The pattern of visually evoked effects in abducens and neck motoneurons was investigated by intracellular recording in chloralose anesthetized cats. Following a single shock to the ipsilateral optic disk (ODi), excitatory postsynaptic potentials (EPSPs) were recorded from abducens motoneurons. In some case, inhibitory postsynaptic potentials (IPSPs) or mixed PSPs were also evoked from the ODi. Similar EPSPs, IPSPs or mixed PSPs were induced in the dorsal neck motoneurons. The results suggest the possibility of a similar synaptic linkage from the retino-tectal system to abducens and neck motoneurons. Intracellular responses were recorded from tectal neurons after stimulation of the cervical afferents. Stimulation of the ipsi or contralateral C2 dorsal root ganglion evoked EPSPs or IPSPs in the tectal neurons, indicating polysynaptic excitatory and inhibitory connections between neck afferents and tectal neurons.