title: The impact of inhibitory mechanisms in the inner retina on spatial tuning of RGCs.
abstract: Spatial tuning properties of retinal ganglion cells (RGCs) are sharpened by lateral inhibition originating at both the outer and inner plexiform layers. Lateral inhibition in the retina contributes to local contrast enhancement and sharpens edges. In this study, we used dynamic clamp recordings to examine the contribution of inner plexiform inhibition, originating from spiking amacrine cells, to the spatial tuning of RGCs. This was achieved by injecting currents generated from physiologically recorded excitatory and inhibitory stimulus-evoked conductances, into different types of primate and mouse RGCs. We determined the effects of injections of size-dependent conductances in which presynaptic inhibition and/or direct inhibition onto RGCs were partly removed by blocking the activity of spiking amacrine cells. We found that inhibition originating from spiking amacrine cells onto bipolar cell terminals and onto RGCs, work together to sharpen the spatial tuning of RGCs. Furthermore, direct inhibition is crucial for preventing spike generation at stimulus offset. These results reveal how inhibitory mechanisms in the inner plexiform layer contribute to determining size tuning and provide specificity to stimulus polarity.
authors.affiliation: Discipline of Biomedical Science, The University of Sydney, NSW 1825 Australia.|The Bosch Institute, The University of Sydney, NSW 2006 Australia.
authors.forename: Jin Y
authors.initials: JY
authors.lastname: Huang
authors.affiliation: Discipline of Physiology, The University of Sydney, NSW 2006 Australia.|The Bosch Institute, The University of Sydney, NSW 2006 Australia.
authors.forename: Dario A
authors.initials: DA
authors.lastname: Protti
mesh_terms: D025042:Amacrine Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002144:Callithrix; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018408:Patch-Clamp Techniques; D010364:Pattern Recognition, Visual / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology; D046509:Tissue Culture Techniques; D061566:Voltage-Gated Sodium Channels / Q000502:physiology
chemical_list: D026941:Sodium Channel Blockers; D061566:Voltage-Gated Sodium Channels; D013779:Tetrodotoxin