title: Dendritic spikes enhance stimulus selectivity in cortical neurons in vivo.
abstract: Neuronal dendrites are electrically excitable: they can generate regenerative events such as dendritic spikes in response to sufficiently strong synaptic input. Although such events have been observed in many neuronal types, it is not well understood how active dendrites contribute to the tuning of neuronal output in vivo. Here we show that dendritic spikes increase the selectivity of neuronal responses to the orientation of a visual stimulus (orientation tuning). We performed direct patch-clamp recordings from the dendrites of pyramidal neurons in the primary visual cortex of lightly anaesthetized and awake mice, during sensory processing. Visual stimulation triggered regenerative local dendritic spikes that were distinct from back-propagating action potentials. These events were orientation tuned and were suppressed by either hyperpolarization of membrane potential or intracellular blockade of NMDA (N-methyl-d-aspartate) receptors. Both of these manipulations also decreased the selectivity of subthreshold orientation tuning measured at the soma, thus linking dendritic regenerative events to somatic orientation tuning. Together, our results suggest that dendritic spikes that are triggered by visual input contribute to a fundamental cortical computation: enhancing orientation selectivity in the visual cortex. Thus, dendritic excitability is an essential component of behaviourally relevant computations in neurons.
authors.affiliation: 1] Wolfson Institute for Biomedical Research and Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK [2] Department of Cell Biology and Physiology and Neuroscience Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
authors.forename: Spencer L
authors.initials: SL
authors.lastname: Smith
authors.forename: Ikuko T
authors.initials: IT
authors.lastname: Smith
authors.forename: Tiago
authors.initials: T
authors.lastname: Branco
authors.forename: Michael
authors.initials: M
authors.lastname: Häusser
mesh_terms: D000200:Action Potentials; D000818:Animals; D020013:Calcium Signaling; D016292:Procedural Sedation; D003712:Dendrites / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D014793:Visual Cortex / Q000166:cytology*; D014851:Wakefulness / Q000502:physiology
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate