[Neural circuit of the retina subserving processing of color and spatial signals as revealed by studies on dissociated solitary neurons].
The trichromatic signals of cone photoreceptors is converted into color opponent signals by interaction between cones and horizontal cells. It has been proposed that the interaction involves a subtype-specific feedforward as well as feedback connections between these two types of cells. In our recent studies, we obtained evidence to strongly support this hypothesis. Solitary cone photoreceptors were enzymatically dissociated from the turtle retina, and their responsiveness to gamma-aminobutyric acid (GABA), a neurotransmitter of the monophasic horizontal cells (a subtype of horizontal cells), was examined. Ionophoretic application of GABA hyperpolarized red-sensitive and green-sensitive cones, but not blue-sensitive cones. GABA sensitivity was confined to the cone pedicle which is the site of synaptic contacts with the horizontal cell. GABA bound to type A receptors and opened chloride channels. The retinal circuitry subserving the generation of color opponent processes and of the center-surround antagonism is discussed in relation to these observations.
Kaneko
A
A
National Institute for Physiological Sciences, Okazaki, Japan.
D000818:Animals; D003118:Color Perception; D005246:Feedback; D009474:Neurons / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D014426:Turtles; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005680:gamma-Aminobutyric Acid