title: NMDA spike/plateau potentials in dendrites of thalamocortical neurons.
abstract: Dendritic NMDA spike/plateau potentials, first discovered in cortical pyramidal neurons, provide supralinear integration of synaptic inputs on thin and distal dendrites, thereby increasing the impact of these inputs on the soma. The more specific functional role of these potentials has been difficult to clarify, partly due to the complex circuitry of cortical neurons. Thalamocortical (TC) neurons in the dorsal lateral geniculate nucleus participate in simpler circuits. They receive their primary afferent input from retina and send their output to visual cortex. Cortex, in turn, regulates this output through massive feedback to distal dendrites of the TC neurons. The TC neurons can operate in two modes related to behavioral states: burst mode prevailing during sleep, when T-type calcium bursts largely disrupt the transfer of signals from retina to cortex, and tonic mode, which provides reliable transfer of retinal signals to cortex during wakefulness. We studied dendritic potentials in TC neurons with combined two-photon calcium imaging and whole-cell recording of responses to local dendritic glutamate iontophoresis in acute brain slices from mice. We found that NMDA spike/plateaus can be elicited locally at distal dendrites of TC neurons. We suggest that these dendritic potentials have important functions in the cortical regulation of thalamocortical transmission. NMDA spike/plateaus can induce shifts in the functional mode from burst to tonic by blockade of T-type calcium conductances. Moreover, in tonic mode, they can facilitate the transfer of retinal signals to cortex by depolarization of TC neurons.
authors.affiliation: Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, 904-0495 Japan, and sigita.augustinaite@oist.jp.
authors.forename: Sigita
authors.initials: S
authors.lastname: Augustinaite
authors.affiliation: Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa, 904-0495 Japan, and.
authors.forename: Bernd
authors.initials: B
authors.lastname: Kuhn
authors.affiliation: Centre for Molecular Biology and Neuroscience and the Letten Centre-Laboratory for Molecular Neuroscience, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway.
authors.forename: Paul Johannes
authors.initials: PJ
authors.lastname: Helm
authors.affiliation: Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway.
authors.forename: Paul
authors.initials: P
authors.lastname: Heggelund
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D003712:Dendrites / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D013788:Thalamus / Q000187:drug effects / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D010879:Piperazines; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; C050592:3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid
keywords: LGN; NMDA spike; NMDA spike/plateau potential; cortical feedback; dendritic integration; thalamocortical