The authors evaluated floccular activity with fMRI during the performance of vertical smooth pursuit eye movements in four patients with downbeat nystagmus(DBN)due to cerebellar degeneration and in 16 healthy controls...The authors evaluated floccular activity with fMRI during the performance of vertical smooth pursuit eye movements in four patients with downbeat nystagmus(DBN)due to cerebellar degeneration and in 16 healthy controls.Region of interest analysis revealed a significantly diminished activation of both floccular lobes during downward but not upward pursuit in DBN.These imaging data support the view that a functional deficiency of the flocculi in downward pursuit causes DBN.展开更多
The effect of the potassium channel blocker 4-aminopyridine(4-AP) on spontan eous upbeat nystagmus (UBN) was investigated with the search coil technique duri ng fixation in different gaze positions and smooth pursuit ...The effect of the potassium channel blocker 4-aminopyridine(4-AP) on spontan eous upbeat nystagmus (UBN) was investigated with the search coil technique duri ng fixation in different gaze positions and smooth pursuit in a patient before a nd after ingestion of 10 mg 4-AP. UBN was reduced from 8.6 deg/s to 2.0 deg/s b y 4-AP causing subjective relief from distressing oscillopsia, and impaired upw ard smooth pursuit was restored(gains: before medication 0.38; after medication 0.86). In the dark, UBN was slightly stronger and not affected by 4-AP. We prop ose that 4-AP improved the function of cerebellar pathways that mediate gaze ho lding and smooth pursuit by intensifying the excitability of cerebellar Purkinje cells.展开更多
文摘The authors evaluated floccular activity with fMRI during the performance of vertical smooth pursuit eye movements in four patients with downbeat nystagmus(DBN)due to cerebellar degeneration and in 16 healthy controls.Region of interest analysis revealed a significantly diminished activation of both floccular lobes during downward but not upward pursuit in DBN.These imaging data support the view that a functional deficiency of the flocculi in downward pursuit causes DBN.
文摘The effect of the potassium channel blocker 4-aminopyridine(4-AP) on spontan eous upbeat nystagmus (UBN) was investigated with the search coil technique duri ng fixation in different gaze positions and smooth pursuit in a patient before a nd after ingestion of 10 mg 4-AP. UBN was reduced from 8.6 deg/s to 2.0 deg/s b y 4-AP causing subjective relief from distressing oscillopsia, and impaired upw ard smooth pursuit was restored(gains: before medication 0.38; after medication 0.86). In the dark, UBN was slightly stronger and not affected by 4-AP. We prop ose that 4-AP improved the function of cerebellar pathways that mediate gaze ho lding and smooth pursuit by intensifying the excitability of cerebellar Purkinje cells.
