Synaptic integration in tuft dendrites of layer 5 pyramidal neurons: a new unifying principle.
Tuft dendrites are the main target for feedback inputs innervating neocortical layer 5 pyramidal neurons, but their properties remain obscure. We report the existence of N-methyl-D-aspartate (NMDA) spikes in the fine distal tuft dendrites that otherwise did not support the initiation of calcium spikes. Both direct measurements and computer simulations showed that NMDA spikes are the dominant mechanism by which distal synaptic input leads to firing of the neuron and provide the substrate for complex parallel processing of top-down input arriving at the tuft. These data lead to a new unifying view of integration in pyramidal neurons in which all fine dendrites, basal and tuft, integrate inputs locally through the recruitment of NMDA receptor channels relative to the fixed apical calcium and axosomatic sodium integration points.
Larkum
Matthew E
ME
Department of Physiology, University of Berne, Bühlplatz 5, 3012 Berne, Switzerland. matthew.larkum@gmail.com
Nevian
Thomas
T
Sandler
Maya
M
Polsky
Alon
A
Schiller
Jackie
J
D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000502:physiology; D020013:Calcium Signaling; D003198:Computer Simulation; D003712:Dendrites / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials; D066298:In Vitro Techniques; D008959:Models, Neurological; D016202:N-Methylaspartate / Q000378:metabolism; D019579:Neocortex / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013569:Synapses / Q000502:physiology*; D055366:Synaptic Potentials
D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; D012964:Sodium