Title

APB treatment of the neonatal cat retina induces a long-lasting functional reorganization in response properties of LGN neurons

Document Type

Journal Article

Publication Date

2-15-1996

Journal

Investigative Ophthalmology and Visual Science

Volume

37

Issue

3

Abstract

Purpose. Repeated intraocular injections of APB, the metabotropic glutamate agonist, has been shown to arrest the normal stratification of dendritic processes of developing retinal ganglion cells into ON and OFF sublaminae (Bodnarenko & Chalupa, Nature, 1993). The purpose of the present study was to examine the functional consequences of APB treatment substantially longer than that used previously. Methods. At postnatal day 3, cats were administered a single injection of APB daily (with a 2-day respite during the week-ends) until P30. Several months later we recorded the responses of lateral geniculate neurons in the A and A1 laminae innervated by the normal and treated eye. A computer controlled system presented stimuli above and below background for the analysis of receptive-field center responses. PSTHs and response rasters were obtained online and stored on disk. Results. In the A or A1 layer innervated by the untreated eye, all cells responded to visual stimuli in the conventional manner with receptive fields that were either ON- or OFF-center. In contrast, a high proportion of the cells recorded in the geniculate layers innervated by the treated eye yielded consistent and robust ON-OFF responses. The proportion of such unusual cells was virtually identical to the proportion of multistratified retinal ganglion cells within the APB-treated retinas. Conclusions. The findings indicate that treating the neonatal cat retina with APB produces a marked reorganization in visual receptive fields, resulting in ON-OFF responses. Most likely this functional reorganization reflects the persistence of retinal ganglion cells with multistratified dendrites within the EPL.

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