title: NMDA Receptors Multiplicatively Scale Visual Signals and Enhance Directional Motion Discrimination in Retinal Ganglion Cells.
abstract: Postsynaptic responses in many CNS neurons are typically small and variable, often making it difficult to distinguish physiologically relevant signals from background noise. To extract salient information, neurons are thought to integrate multiple synaptic inputs and/or selectively amplify specific synaptic activation patterns. Here, we present evidence for a third strategy: directionally selective ganglion cells (DSGCs) in the mouse retina multiplicatively scale visual signals via a mechanism that requires both nonlinear NMDA receptor (NMDAR) conductances in DSGC dendrites and directionally tuned inhibition provided by the upstream retinal circuitry. Postsynaptic multiplication enables DSGCs to discriminate visual motion more accurately in noisy visual conditions without compromising directional tuning. These findings demonstrate a novel role for NMDARs in synaptic processing and provide new insights into how synaptic and network features interact to accomplish physiologically relevant neural computations.
authors.affiliation: Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA. Electronic address: polegpolskya@mail.nih.gov.
authors.forename: Alon
authors.initials: A
authors.lastname: Poleg-Polsky
authors.affiliation: Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Diamond
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D008027:Light; D008274:Magnesium / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009622:Noise; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation; D050638:Receptors, Dopamine D4 / Q000235:genetics / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D055366:Synaptic Potentials / Q000187:drug effects / Q000502:physiology; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000494:pharmacology
chemical_list: C493600:Drd4 protein, mouse; D018683:Excitatory Amino Acid Agents; D016194:Receptors, N-Methyl-D-Aspartate; D050638:Receptors, Dopamine D4; D005680:gamma-Aminobutyric Acid; D008274:Magnesium