Dendritic spikes in apical dendrites of neocortical layer 2/3 pyramidal neurons

Larkum, Matthew Evan; Waters, Jack; Sakmann, Bert; Helmchen, Fritjof (2007). Dendritic spikes in apical dendrites of neocortical layer 2/3 pyramidal neurons. Journal of neuroscience, 27(34), pp. 8999-9008. Washington, D.C.: Society for Neuroscience 10.1523/JNEUROSCI.1717-07.2007

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Layer 2/3 (L2/3) pyramidal neurons are the most abundant cells of the neocortex. Despite their key position in the cortical microcircuit, synaptic integration in dendrites of L2/3 neurons is far less understood than in L5 pyramidal cell dendrites, mainly because of the difficulties in obtaining electrical recordings from thin dendrites. Here we directly measured passive and active properties of the apical dendrites of L2/3 neurons in rat brain slices using dual dendritic-somatic patch-clamp recordings and calcium imaging. Unlike L5 cells, L2/3 dendrites displayed little sag in response to long current pulses, which suggests a low density of I(h) in the dendrites and soma. This was also consistent with a slight increase in input resistance with distance from the soma. Brief current injections into the apical dendrite evoked relatively short (half-width 2-4 ms) dendritic spikes that were isolated from the soma for near-threshold currents at sites beyond the middle of the apical dendrite. Regenerative dendritic potentials and large concomitant calcium transients were also elicited by trains of somatic action potentials (APs) above a critical frequency (130 Hz), which was slightly higher than in L5 neurons. Initiation of dendritic spikes was facilitated by backpropagating somatic APs and could cause an additional AP at the soma. As in L5 neurons, we found that distal dendritic calcium transients are sensitive to a long-lasting block by GABAergic inhibition. We conclude that L2/3 pyramidal neurons can generate dendritic spikes, sharing with L5 pyramidal neurons fundamental properties of dendritic excitability and control by inhibition.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Physiology
UniBE Contributor:	Larkum, Matthew
ISSN:	0270-6474
ISBN:	17715337
Publisher:	Society for Neuroscience
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:53
Last Modified:	05 Dec 2022 14:16
Publisher DOI:	10.1523/JNEUROSCI.1717-07.2007
PubMed ID:	17715337
Web of Science ID:	000248953400003
URI:	https://boris.unibe.ch/id/eprint/22295 (FactScience: 33912)