Format

Send to

Choose Destination
J Neurophysiol. 2015 Aug;114(2):857-68. doi: 10.1152/jn.00238.2015. Epub 2015 Jun 10.

Abnormal tuning of saccade-related cells in pontine reticular formation of strabismic monkeys.

Author information

1
Washington National Primate Research Center, University of Washington, Seattle, Washington; mark.walton@wanprc.org.
2
Washington National Primate Research Center, University of Washington, Seattle, Washington; Department of Ophthalmology, University of Washington, Seattle, Washington; and Department of Biological Structure, University of Washington, Seattle, Washington.

Abstract

Strabismus is a common disorder, characterized by a chronic misalignment of the eyes and numerous visual and oculomotor abnormalities. For example, saccades are often highly disconjugate. For humans with pattern strabismus, the horizontal and vertical disconjugacies vary with eye position. In monkeys, manipulations that disturb binocular vision during the first several weeks of life result in a chronic strabismus with characteristics that closely match those in human patients. Early onset strabismus is associated with altered binocular sensitivity of neurons in visual cortex. Here we test the hypothesis that brain stem circuits specific to saccadic eye movements are abnormal. We targeted the pontine paramedian reticular formation, a structure that directly projects to the ipsilateral abducens nucleus. In normal animals, neurons in this structure are characterized by a high-frequency burst of spikes associated with ipsiversive saccades. We recorded single-unit activity from 84 neurons from four monkeys (two normal, one exotrope, and one esotrope), while they made saccades to a visual target on a tangent screen. All 24 neurons recorded from the normal animals had preferred directions within 30° of pure horizontal. For the strabismic animals, the distribution of preferred directions was normal on one side of the brain, but highly variable on the other. In fact, 12/60 neurons recorded from the strabismic animals preferred vertical saccades. Many also had unusually weak or strong bursts. These data suggest that the loss of corresponding binocular vision during infancy impairs the development of normal tuning characteristics for saccade-related neurons in brain stem.

KEYWORDS:

PPRF; esotropia; exotropia; monkey; strabismus

PMID:
26063778
PMCID:
PMC4533063
DOI:
10.1152/jn.00238.2015
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center