Evidence for interactive locomotor and oculomotor deficits in cerebellar patients during visually guided stepping

• Published in: Experimental brain research Vol. 135; no. 4; pp. 437 - 454
• Main Authors: CROWDY, K. A, HOLLANDS, M. A, FERGUSON, I. T, MARPLE-HORVAT, D. E
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.12.2000
• Subjects: Adult; Biological and medical sciences; Cerebellar Ataxia - physiopathology; Cerebellum - physiology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Female; Fixation, Ocular - physiology; Gait - physiology; Humans; Locomotion - physiology; Male; Medical sciences; Middle Aged; Neurology; oculomotor integration; Oculomotor Nerve - physiology; Photic Stimulation; Psychomotor Performance - physiology; Saccades - physiology; Human; Nervous system diseases; Gait; Visual fixation; Motor control; Eye movement; Cerebral disorder; Saccadic eye movement; Locomotion; Walking; Motility disorder; Cerebellar disease; Central nervous system disease; Body movement; Degenerative disease; Oculomotor syndrome; Visuomotor control; Visual task
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s002210000539

Eight patients suffering from primary cerebellar degenerative diseases undertook a walkway task, demanding precise foot placement at each step, and a visual fixation task, requiring only eye movements. Step cycle and horizontal eye movements were recorded throughout the tasks and compared to those of healthy adults (including age- and sex-matched controls). Cerebellar patients displayed both locomotor and oculomotor deficits. Increases in duration of the stance, swing and double support phases of the step cycle were all shown to contribute to ataxic gait. Dysmetric saccades to fixate the footfall targets were seen more frequently in patients than in controls. These hypometric saccades were followed by one or more corrective saccades (patients: >45% accompanied by one or more corrective saccades; controls: <10% accompanied by a single corrective saccade). Similarities between the oculomotor deficits displayed by patients during the visual fixation task and when walking indicate that the latter are not merely a consequence of ataxic gait. The existence of several links between these locomotor and oculomotor deficits provides evidence for considerable interaction between the two control systems in the production of patterned eye and stepping movements. These results also suggest that the cerebellum plays an active role in the co-ordination of visually guided eye and limb movements during visually guided stepping.