HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 99/5/2584    most recent 00011.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Major, G. Articles by Tank, D. W. Search for Related Content PubMed PubMed Citation Articles by Major, G. Articles by Tank, D. W.

Spatiotemporally Graded NMDA Spike/Plateau Potentials in Basal Dendrites of Neocortical Pyramidal Neurons

¹Molecular Biology and Physics, Princeton University, Princeton, New Jersey; ²Physiology, Technion Medical School, Haifa, Israel; and ³Max-Planck Institut für Medizinische Forschung, Heidelberg, Germany

Submitted 4 January 2008; accepted in final form 5 March 2008

Glutamatergic inputs clustered over 20–40 µm can elicit local N-methyl-D-aspartate (NMDA) spike/plateau potentials in terminal dendrites of cortical pyramidal neurons, inspiring the notion that a single terminal dendrite can function as a decision-making computational subunit. A typical terminal basal dendrite is 100–200 µm long: could it function as multiple decision-making subunits? We test this by sequential focal stimulation of multiple sites along terminal basal dendrites of layer 5 pyramidal neurons in rat somatosensory cortical brain slices, using iontophoresis or uncaging of brief glutamate pulses. There was an approximately sevenfold spatial gradient in average spike/plateau amplitude measured at the soma, from 3 mV for distal inputs to 23 mV for proximal inputs. Spike/plateaus were NMDA receptor (NMDAR) conductance-dominated at all locations. Large Ca²⁺ transients accompanied spike/plateaus over a 10- to 40-µm zone around the input site; smaller Ca²⁺ transients extended approximately uniformly to the dendritic tip. Spike/plateau duration grew with increasing glutamate and depolarization; high Ca²⁺ zone size grew with spike/plateau duration. The minimum high Ca²⁺ zone half-width (just above NMDA spike threshold) increased from distal (10 µm) to proximal locations (25 µm), as did the NMDA spike glutamate threshold. Depolarization reduced glutamate thresholds. Simulations exploring multi-site interactions based on this demonstrate that if appropriately timed and localized inputs occur in vivo, a single basal dendrite could correspond to a cascade of multiple co-operating dynamic decision-making subunits able to retain information for hundreds of milliseconds, with increasing influence on neural output from distal to proximal. Dendritic NMDA spike/plateaus are thus well-suited to support graded persistent firing.

This article has been cited by other articles:

				A. Polsky, B. Mel, and J. Schiller Encoding and Decoding Bursts by NMDA Spikes in Basal Dendrites of Layer 5 Pyramidal Neurons J. Neurosci., September 23, 2009; 29(38): 11891 - 11903. [Abstract] [Full Text] [PDF]

				E. Idoux, D. Eugene, A. Chambaz, C. Magnani, J. A. White, and L. E. Moore Control of Neuronal Persistent Activity by Voltage-Dependent Dendritic Properties J Neurophysiol, September 1, 2008; 100(3): 1278 - 1286. [Abstract] [Full Text] [PDF]