Journal of Neuroscience, Vol 2, 1486-1493, Copyright © 1982 by Society for Neuroscience
Horizontal cells in the retina of the rabbit
RF Dacheux and E Raviola
The light responses, morphology, and connections of horizontal cells (HCs)
were studied in the retina of the rabbit using intracellular recordings and
the injection of visible markers. Two types of HCs were identified,
axonless and axon-bearing HCs. Axonless HCs and the somatic end of
axon-bearing HCs respond to white light of varying intensity with graded
hyperpolarizations; both display a transient superimposed on the sustained
hyperpolarization at stimulus initiation and a small rod aftereffect at the
cessation of high intensity stimuli. Anatomically, both are connected to
cones, but their responses also suggest rod influence. Both summate stimuli
from a retinal area which is much larger than their respective fields.
However, only axonless HCs transfer a fluorescent, low molecular weight dye
to adjoining, homologous cells. The axon terminal of axon-bearing HCs has
response properties different from those of the cell body: the transient at
stimulus initiation is absent; furthermore, at high levels of illumination,
the rod aftereffect becomes equal in amplitude to the primary
hyperpolarization. Anatomically, it is connected to rods, but its responses
also suggest cone influence. Its receptive field approximates in diameter
its anatomical spread and it does not transfer fluorescent dye to its
neighbors.
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