NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Comparison of Predictable Smooth Ocular and Combined Eye-Head Tracking Behaviour in Patients with Lesions Affecting the Brainstem and CerebellumWe compared the ability of eight normal subjects and 15 patients with brainstem or cerebellar disease to follow a moving visual stimulus smoothly with either the eyes alone or with combined eye-head tracking. The visual stimulus was either a laser spot (horizontal and vertical planes) or a large rotating disc (torsional plane), which moved at one sinusoidal frequency for each subject. The visually enhanced Vestibulo-Ocular Reflex (VOR) was also measured in each plane. In the horizontal and vertical planes, we found that if tracking gain (gaze velocity/target velocity) for smooth pursuit was close to 1, the gain of combined eye-hand tracking was similar. If the tracking gain during smooth pursuit was less than about 0.7, combined eye-head tracking was usually superior. Most patients, irrespective of diagnosis, showed combined eye-head tracking that was superior to smooth pursuit; only two patients showed the converse. In the torsional plane, in which optokinetic responses were weak, combined eye-head tracking was much superior, and this was the case in both subjects and patients. We found that a linear model, in which an internal ocular tracking signal cancelled the VOR, could account for our findings in most normal subjects in the horizontal and vertical planes, but not in the torsional plane. The model failed to account for tracking behaviour in most patients in any plane, and suggested that the brain may use additional mechanisms to reduce the internal gain of the VOR during combined eye-head tracking. Our results confirm that certain patients who show impairment of smooth-pursuit eye movements preserve their ability to smoothly track a moving target with combined eye-head tracking.
Document ID
19970022714
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Grant, Michael P.
(Case Western Reserve Univ. Cleveland, OH United States)
Leigh, R. John
(Case Western Reserve Univ. Cleveland, OH United States)
Seidman, Scott H.
(Case Western Reserve Univ. Cleveland, OH United States)
Riley, David E.
(Case Western Reserve Univ. Cleveland, OH United States)
Hanna, Joseph P.
(Case Western Reserve Univ. Cleveland, OH United States)
Date Acquired
August 17, 2013
Publication Date
May 12, 1992
Publication Information
Publication: Brain
Publisher: Oxford University Press
Volume: 115
Subject Category
Behavioral Sciences
Report/Patent Number
NAS 1.26:204272
NASA-CR-204272
Accession Number
97N72140
Funding Number(s)
CONTRACT_GRANT: NAG9-571
Distribution Limits
Public
Copyright
Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available