Skip Navigation

This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (5)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Barton, J. J.
Right arrow Articles by Sharpe, J. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Barton, J. J.
Right arrow Articles by Sharpe, J. A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Brain, Vol 121, Issue 6 1165-1183, Copyright © 1998 by Oxford University Press

ARTICLES

Ocular tracking of step-ramp targets by patients with unilateral cerebral lesions

JJ Barton and JA Sharpe
Division of Neurology, Toronto Hospital, University of Toronto, Canada. jbarton@bidmc.harvard.edu

The relationship of sinusoidal smooth pursuit defects to pursuit defects with step-ramp targets in patients with cerebral lesions is unclear. We examined pursuit and saccades to both step-ramp and sinusoidal targets in 17 patients with unilateral cerebral lesions. Two types of pursuit defects were found. One group of three patients had ipsi-directional sinusoidal pursuit defects from lesions to the posterior internal capsule. Their chief abnormality with step-ramp targets was increased contra-directional pursuit. Their ipsi- directional step-ramp pursuit was often normal and disproportionately better than their ipsi-directional sinusoidal pursuit. Another patient with a parietal lesion had a second type of pursuit defect. He had low- normal sinusoidal pursuit bilaterally, but decreased ipsi- and contra- directional step-ramp pursuit. Also, he had an abnormal contra- directional drift after saccades to stationary targets. Despite these pursuit defects, saccadic accuracy did not show poor compensation for target motion in either patient type. The patient with the parietal lesion also had increased latencies for contralateral saccades. Recovery of pursuit was studied in one patient with an infarct of the posterior internal capsule. Initially he had a contra-directional bias that caused decreased ipsi-directional pursuit, increased contra- directional pursuit, and a contra-directional drift after saccades to stationary targets. Four months later, ipsi-directional pursuit and the post-saccadic drift to stationary targets had recovered, but contra- directional pursuit remained abnormally high. We conclude that lesions of descending pursuit tracts in the internal capsule are characterized by a contra-directional bias which recovers partly through a direction- specific adaptation. Lesions that affect the human homologue of posterior parietal cortex cause asymmetric bi-directional defects in pursuit initiation and increased contralateral saccadic latencies.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Cereb CortexHome page
A. S. Drew and P. van Donkelaar
The Contribution of the Human FEF and SEF to Smooth Pursuit Initiation
Cereb Cortex, November 1, 2007; 17(11): 2618 - 2624.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.