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Y retinal terminals contact interneurons in the cat dorsal lateral geniculate nucleus
Author(s) -
Datskovskaia Aygul,
Carden W. Breckinridge,
Bickford Martha E.
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/1096-9861(20010129)430:1<85::aid-cne1016>3.0.co;2-k
Subject(s) - neuroscience , biotinylated dextran amine , retinal waves , retinal , superior colliculus , biology , geniculate , postsynaptic potential , retina , axon , lateral geniculate nucleus , nucleus , retinal ganglion cell , intrinsically photosensitive retinal ganglion cells , biochemistry , receptor
One of the largest influences on dorsal lateral geniculate nucleus (dLGN) activity comes from interneurons, which use the neurotransmitter γ‐aminobutyric acid (GABA). It is well established that X retinogeniculate terminals contact interneurons and thalamocortical cells in complex synaptic arrangements known as glomeruli. However, there is little anatomical evidence for the involvement of dLGN interneurons in the Y pathway. To determine whether Y retinogeniculate axons contact interneurons, we injected the superior colliculus (SC) with biotinylated dextran amine (BDA) to backfill retinal axons, which also project to the SC. Within the A lamina of the dLGN, this BDA labeling allowed us to distinguish Y retinogeniculate axons from X retinogeniculate axons, which do not project to the SC. In BDA‐labeled tissue prepared for electron microscopic analysis, we subsequently used postembedding immunocytochemical staining for GABA to distinguish interneurons from thalamocortical cells. We found that the majority of profiles postsynaptic to Y retinal axons were GABA‐negative dendrites of thalamocortical cells (117/200 or 58.5%). The remainder (83/200 or 41.5%) were GABA‐positive dendrites, many of which contained vesicles (59/200 or 29.5%). Thus, Y retinogeniculate axons do contact interneurons. However, these contacts differed from X retinogeniculate axons, in that triadic arrangements were rare. This indicates that the X and Y pathways participate in unique circuitries but that interneurons are involved in the modulation of both pathways. J. Comp. Neurol. 430:85–100, 2001. © 2000 Wiley‐Liss, Inc.