Pontine Lesions Cause Deficits of Vergence to Step but not to Ramp Targets

The pontine nuclei are part of the cortico-ponto-cerebellar loop of conjugate eye movements, i.e., saccades and smooth pursuit. There is some evidence that the pontine nuclei may also be important in disconjugate eye movements (vergence). As conjugate eye movements, vergence can be separated in vergence to ramp targets (slow vergence) or step targets (fast vergence). It is unknown so far whether pontine nuclei selectively impair slow or fast vergence. To test this hypothesis binocular eye movements were recorded with the scleral search coil system in two patients with median pontine lesions and in 10 healthy con…