CJO - Abstract - Expansion of visual receptive fields in experimental glaucoma

Visual Neuroscience (2006), 23 : 137-142 Cambridge University Press

Copyright © 2006 Cambridge University Press

doi:10.1017/S0952523806231122

Published online by Cambridge University Press 09 Mar 2006

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Expansion of visual receptive fields in experimental glaucoma

WAYNE MICHAEL KING ^a1 ^a2 , VIMAL SARUP ^a1 , YVES SAUVÉ ^a3 , COLLEEN M. MORELAND ^a1 , DAVID O. CARPENTER ^a2 and S.C. SHARMA ^a1 ^c1
^a1 Departments of Ophthalmology and Cell Biology & Anatomy, New York Medical College, Valhalla, New York
^a2 Institute for Health and the Environment, University at Albany, Rensselaer, New York
^a3 Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada

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Abstract

Glaucoma is a major cause of blindness and is characterized by death of retinal ganglion cells. In a rat model of glaucoma in which intraocular pressure is raised by cautery of episcleral veins, the somata and dendritic arbors of surviving retinal ganglion cells expand. To assess physiological consequences of this change, we have measured visual receptive-field size in a primary retinal target, the superior colliculus. Using multiunit recording, receptive-field sizes were measured for glaucomatous eyes and compared to both those measured for contralateral control eyes and to homolateral eyes of unoperated animals. Episcleral vein occlusion increased intraocular pressure. This was accompanied by a significant increase in receptive-field size across the superior colliculus. The expansion of receptive fields was proportional to both degree and duration of the increase of intraocular pressure. We suggest that this increase in the size of receptive fields of glaucomatous eyes may be related to the increase in the size of dendritic arbors of the surviving ganglion cells in retina.

(Received July 27 2005)
(Accepted October 19 2005)

Key Words: Glaucoma; Superior colliculus; Receptive field; Rat; Electrophysiology.

Correspondence:
^c1 Address correspondence and reprint requests to: S.C. Sharma, Departments of Ophthalmology, Cell Biology & Anatomy, SB Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA. E-mail: Sharma@nymc.edu