Robust but delayed thalamocortical activation of dendritic-targeting inhibitory interneurons

Tan, Z., Hu, H., Huang, Z. J., Agmon, A. (February 2008) Robust but delayed thalamocortical activation of dendritic-targeting inhibitory interneurons. Proc Natl Acad Sci U S A, 105 (6). pp. 2187-2192.

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Abstract

GABA-releasing cortical interneurons are crucial for the neural transformations underlying sensory perception, providing "feedforward" inhibition that constrains the temporal window for synaptic integration. To mediate feedforward inhibition, inhibitory interneurons need to fire in response to ascending thalamocortical inputs, and most previous studies concluded that ascending inputs activate mainly or solely proximally targeting, parvalbumin-containing "fast-spiking" interneurons. However, when thalamocortical axons fire at frequencies that are likely to occur during natural exploratory behavior, activation of fast-spiking interneurons is rapidly and strongly depressed, implying the paradoxical conclusion that feedforward inhibition is absent when it is most needed. To address this issue, we took advantage of lines of transgenic mice in which either parvalbumin- or somatostatin-containing interneurons express GFP and recorded the responses of interneurons from both subtypes to thalamocortical stimulation in vitro. We report that during thalamocortical activation at behaviorally expected frequencies, fast-spiking interneurons were indeed activated only transiently because of rapid depression of their thalamocortical inputs, but a subset of layer 5 somatostatin-containing interneurons were robustly and persistently activated after a delay, due to the facilitation and temporal summation of their thalamocortical excitatory postsynaptic potentials. Somatostatin-containing interneurons are considered distally targeting. Thus, they are likely to provide delayed dendritic inhibition during exploratory behavior, contributing to the maintenance of a balance between cortical excitation and inhibition while leaving a wide temporal window open for synaptic integration and plasticity in distal dendrites.

Item Type:	Paper
Subjects:	bioinformatics > genomics and proteomics > small molecules > GABAergic organs, tissues, organelles, cell types and functions > cell types and functions > cell types > dendritic cells organs, tissues, organelles, cell types and functions > cell types and functions > cell types > dendritic cells organs, tissues, organelles, cell types and functions > cell types and functions > cell types > dendritic cells organism description > animal > mammal > rodent > mouse organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > neural plasticity neurobiology organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons organs, tissues, organelles, cell types and functions > cell types and functions > cell types > neurons
CSHL Authors:	Huang, Z. Josh
Communities:	CSHL labs > Huang lab
Depositing User:	CSHL Librarian
Date:	12 February 2008
Date Deposited:	10 Apr 2012 16:30
Last Modified:	10 Jan 2017 15:50
PMCID:	PMC2538896
Related URLs:	Publisher
URI:	https://repository.cshl.edu/id/eprint/25813

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