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Editors Selection IGR 16-4

Basic science: Dendritic atrophy

Comment by Yeni Yucel on:

13158 Structure-function relations of parasol cells in the normal and glaucomatous primate retina, Weber AJ; Harman CD, Investigative Ophthalmology and Visual Science, 2005; 46: 3197-3207

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In their elegant study, Weber and Harman (845) show for the first time that in experimental primate glaucoma, surviving retinal ganglion cells with dendritic atrophy, while retaining normal intrinsic electrical properties, are less responsive to visual stimuli.

in vitro experiments were conducted using an eye cup preparation in which glaucoma eyes were compared to the fellow eye and eyes of untreated normal monkeys. Intrinsic biophysical properties of surviving RGCs and their responses to visual stimuli were recorded intracellularly. Although RGCs were axotomized, most of their physiological characteristics were retained. Classification of RGCs was based on characteristic dendritic arborization patterns revealed by injection of dye into the cell body. This suggests that specific functional modalities may be affected without parasol RGC loss.

RGCs with significant dendritic arborization changes, showed a reduction in the response to visual stimuli with higher temporal frequency

The atrophy observed in the dendrites of surviving RGCs, corresponded to reduced visual function in this study, and this finding is highly relevant to understanding glaucomatous damage. Dendritic atrophy has been also described in target neurons of the lateral geniculate nucleus in experimental primate glaucoma, in the absence of detectable RGC loss,¹ and raises the possibility for reduced function. Future studies of spatiotemporal response properties of the 12 remaining RGC cell types² will be very important to determine whether functional changes in surviving RGCs are cell-type specific or diffuse.

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