title: Role of the mouse retinal photoreceptor ribbon synapse in visual motion processing for optokinetic responses.
abstract: The ribbon synapse is a specialized synaptic structure in the retinal outer plexiform layer where visual signals are transmitted from photoreceptors to the bipolar and horizontal cells. This structure is considered important in high-efficiency signal transmission; however, its role in visual signal processing is unclear. In order to understand its role in visual processing, the present study utilized Pikachurin-null mutant mice that show improper formation of the photoreceptor ribbon synapse. We examined the initial and late phases of the optokinetic responses (OKRs). The initial phase was examined by measuring the open-loop eye velocity of the OKRs to sinusoidal grating patterns of various spatial frequencies moving at various temporal frequencies for 0.5 s. The mutant mice showed significant initial OKRs with a spatiotemporal frequency tuning (spatial frequency, 0.09 ± 0.01 cycles/°; temporal frequency, 1.87 ± 0.12 Hz) that was slightly different from the wild-type mice (spatial frequency, 0.11 ± 0.01 cycles/°; temporal frequency, 1.66 ± 0.12 Hz). The late phase of the OKRs was examined by measuring the slow phase eye velocity of the optokinetic nystagmus induced by the sinusoidal gratings of various spatiotemporal frequencies moving for 30 s. We found that the optimal spatial and temporal frequencies of the mutant mice (spatial frequency, 0.11 ± 0.02 cycles/°; temporal frequency, 0.81 ± 0.24 Hz) were both lower than those in the wild-type mice (spatial frequency, 0.15 ± 0.02 cycles/°; temporal frequency, 1.93 ± 0.62 Hz). These results suggest that the ribbon synapse modulates the spatiotemporal frequency tuning of visual processing along the ON pathway by which the late phase of OKRs is mediated.
authors.affiliation: Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan; CREST, Japan Science Technology Agency, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sugita
authors.affiliation: Department of Developmental Biology, Osaka Bioscience Institute, Osaka, Japan; Department of Ophthalmology, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Araki
authors.affiliation: Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan; CREST, Japan Science Technology Agency, Tokyo, Japan; Department of Developmental Biology, Osaka Bioscience Institute, Osaka, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Chaya
authors.affiliation: Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawano
authors.affiliation: Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan; CREST, Japan Science Technology Agency, Tokyo, Japan; Department of Developmental Biology, Osaka Bioscience Institute, Osaka, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Furukawa
authors.affiliation: Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Miura
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009039:Motion Perception / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000378:metabolism; D017120:Nystagmus, Optokinetic / Q000502:physiology*; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D013997:Time Factors
chemical_list: D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; C553232:pikachurin protein, mouse