Orientation selectivity in the population of ON-OFF direction-selective ganglion cells in the mouse retina

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dc.contributor.authorRavi Chander, Prathyusha
dc.contributor.supervisorAwatramani, Gautam
dc.date.accessioned2023-04-28T16:37:19Z
dc.date.copyright2023en_US
dc.date.issued2023-04-28
dc.degree.departmentDepartment of Biologyen_US
dc.degree.levelMaster of Science M.Sc.en_US
dc.description.abstractIn the mammalian retina, the orientation-selective (OS) and direction-selective (DS) information are generally thought to be relayed to higher visual centers via distinct ganglion cell types. Contrary to this notion, here I report that classic ON-OFF direction-selective ganglion cells (DSGCs) that are known to encode the four cardinal directions, also encode orientation of static stimuli. The DSGC’s preferred orientations was always orthogonal to its preferred-null axis defined by moving stimuli. To evaluate the synaptic mechanisms underlying orientation selectivity a combination of electrophysiological, optogenetic, and gene knock-out techniques were used to assess the functional properties of all four types of ON-OFF DSGCs. Cumulative results from multiple approaches revealed that the glutamate input to all four types of DSGCs was tuned to the vertical axis. This relies on signals from a specific presynaptic source (the bipolar cell type 5A; BC5A), which appear to be electrically coupled to vertically oriented processes of wide-field amacrine cells. By contrast, the GABAergic inhibition mediated largely by starburst amacrine cells was tuned either along the horizontal or vertical axis, consistent with their well-defined asymmetric wiring pattern. Thus, distinct combinations of inhibition and excitation underlie orientation selectivity in the nasal/temporal and dorsal/ventral coding DSGC populations, only the latter critically relying on the starbursts. Together, my work provides novel insights into how feature selectivity emerges in the hierarchical network in the retina.en_US
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/15044
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectDirection-selectiveen_US
dc.subjectOrientation-selectiveen_US
dc.subjectElectrophysiologyen_US
dc.subjectOptogeneticsen_US
dc.subjectAsymmetric inhibitionen_US
dc.subjectVertical excitationen_US
dc.subjectOS is orthogonal to the P-N axisen_US
dc.subjectdv-DSGCsen_US
dc.subjectnt-DSGCsen_US
dc.subjectSACsen_US
dc.subjectBC5Asen_US
dc.subjectWACsen_US
dc.subjectGap-junction couplingen_US
dc.subjectCx36 gap-junctionsen_US
dc.subjectGenetic knockouten_US
dc.titleOrientation selectivity in the population of ON-OFF direction-selective ganglion cells in the mouse retinaen_US
dc.typeThesisen_US

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