NMDA spikes enhance action potential generation during sensory input.
Recent evidence in vitro suggests that the tuft dendrites of pyramidal neurons are capable of evoking local NMDA receptor-dependent electrogenesis, so-called NMDA spikes. However, it has so far proved difficult to demonstrate their existence in vivo. Moreover, it is not clear whether NMDA spikes are relevant to the output of pyramidal neurons. We found that local NMDA spikes occurred in tuft dendrites of layer 2/3 pyramidal neurons both spontaneously and following sensory input, and had a large influence on the number of output action potentials. Using two-photon activation of an intracellular caged NMDA receptor antagonist (tc-MK801), we found that isolated NMDA spikes typically occurred in multiple branches simultaneously and that sensory stimulation substantially increased their probability. Our results demonstrate that NMDA receptors have a vital role in coupling the tuft region of the layer 2/3 pyramidal neuron to the cell body, enhancing the effectiveness of layer 1 input.
1] Florey Institute, University of Melbourne, Melbourne, Victoria, Australia. [2] Physiologisches Institut, Universität Bern, Bern, Switzerland. [3] NeuroCure Cluster of Excellence, Humboldt University, Berlin, Germany.
Lucy M
LM
Palmer
Bioengineering Department, California Institute of Technology, Pasadena, California, USA.
Adam S
AS
Shai
Department of Chemistry, University of Oxford, Oxford, UK.
James E
JE
Reeve
Department of Chemistry, University of Oxford, Oxford, UK.
Harry L
HL
Anderson
Department of Physiology, Development and Neuroscience, Physiological Laboratory, University of Cambridge, Cambridge, UK.
Ole
O
Paulsen
1] Physiologisches Institut, Universität Bern, Bern, Switzerland. [2] NeuroCure Cluster of Excellence, Humboldt University, Berlin, Germany.
Matthew E
ME
Larkum
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D003712:Dendrites / Q000378:metabolism / Q000502:physiology; D055724:Electrophysiological Phenomena / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D051379:Mice; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate