Synaptic connections of calbindin-immunoreactive cone bipolar cells in the inner plexiform layer of rabbit retina.
In the mammalian retina, information concerning various aspects of an image is transferred in parallel, and cone bipolar cells are thought to play a major role in this parallel processing. We have examined the synaptic connections of calbindin-immunoreactive (IR) ON cone bipolar cells in the inner plexiform layer (IPL) of rabbit retina and have compared these synaptic connections with those that we have previously described for neurokinin 1 (NK1) receptor-IR cone bipolar cells. A total of 325 synapses made by calbindin-IR bipolar axon terminals have been identified in sublamina b of the IPL. The axons of calbindin-IR bipolar cells receive synaptic inputs from amacrine cells through conventional synapses and are coupled to putative AII amacrine cells via gap junctions. The major output from calbindin-IR bipolar cells is to amacrine cell processes. These data resemble our findings for NK1 receptor-IR bipolar cells. However, the incidences of output synapses to ganglion cell dendrites of calbindin-IR bipolar cells are higher compared with the NK1-receptor-IR bipolar cells. On the basis of stratification level and synaptic connections, calbindin-IR ON cone bipolar cells might thus play an important role in the processing of various visual aspects, such as contrast, orientation, and approach sensing, and in transferring rod signals to the ON cone pathway.
Kim
Shin Ae
SA
Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea.
Jung
Choong Ki
CK
Kang
Tae-Hoon
TH
Jeon
Ji Hyun
JH
Cha
Jiook
J
Kim
In-Beom
IB
Chun
Myung-Hoon
MH
D025042:Amacrine Cells / Q000648:ultrastructure; D000818:Animals; D001369:Axons / Q000502:physiology; D064026:Calbindins; D003712:Dendrites / Q000502:physiology; D017629:Gap Junctions / Q000502:physiology; D011817:Rabbits; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D051245:Retinal Bipolar Cells / Q000502:physiology* / Q000648:ultrastructure; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology* / Q000648:ultrastructure; D012165:Retinal Ganglion Cells / Q000648:ultrastructure; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure
D064026:Calbindins; D018040:Receptors, Neurokinin-1; D064030:S100 Calcium Binding Protein G