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Characterization and synaptic connectivity of melanopsin‐containing ganglion cells in the primate retina
Author(s) -
Jusuf Patricia R.,
Lee Sammy C. S.,
Hannibal Jens,
Grünert Ulrike
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2007.05924.x
Subject(s) - intrinsically photosensitive retinal ganglion cells , melanopsin , biology , marmoset , inner nuclear layer , neuroscience , retina , giant retinal ganglion cells , amacrine cell , microbiology and biotechnology , bistratified cell , photopigment , dendrite (mathematics) , retinal ganglion cell , paleontology , geometry , mathematics
Abstract Melanopsin is a photopigment expressed in retinal ganglion cells, which are intrinsically photosensitive and are also involved in retinal circuits arising from rod and cone photoreceptors. This circuitry, however, is poorly understood. Here, we studied the morphology, distribution and synaptic input to melanopsin‐containing ganglion cells in a New World monkey, the common marmoset ( Callithrix jacchus ). The dendrites of melanopsin‐containing cells in marmoset stratify either close to the inner nuclear layer (outer stratifying), or close to the ganglion cell layer (inner stratifying). The dendritic fields of outer‐stratifying cells tile the retina, with little overlap. However, the dendritic fields of outer‐stratifying cells largely overlap with the dendritic fields of inner‐stratifying cells. Thus, inner‐stratifying and outer‐stratifying cells may form functionally independent populations. The synaptic input to melanopsin‐containing cells was determined using synaptic markers (antibodies to C‐terminal binding protein 2, CtBP2, for presumed bipolar synapses, and antibodies to gephyrin for presumed amacrine synapses). Both outer‐stratifying and inner‐stratifying cells show colocalized immunoreactive puncta across their entire dendritic tree for both markers. The density of CtBP2 puncta on inner dendrites was about 50% higher than that on outer dendrites. The density of gephyrin puncta was comparable for outer and inner dendrites but higher than the density of CtBP2 puncta. The inner‐stratifying cells may receive their input from a type of diffuse bipolar cell (DB6). Our results are consistent with the idea that both outer and inner melanopsin cells receive bipolar and amacrine input across their dendritic tree.