Visual representations by cortical somatostatin inhibitory neurons--selective but with weak and delayed responses

Ma, W. P., Liu, B. H., Li, Y. T., Huang, Z. J., Zhang, L. I., Tao, H. W. (October 2010) Visual representations by cortical somatostatin inhibitory neurons--selective but with weak and delayed responses. Journal of Neuroscience, 30 (43). pp. 14371-9. ISSN 0270-6474

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Abstract

Somatostatin-expressing inhibitory (SOM) neurons in the sensory cortex consist mostly of Martinotti cells, which project ascending axons to layer 1. Due to their sparse distribution, the representational properties of these neurons remain largely unknown. By two-photon imaging guided cell-attached recordings, we characterized visual response and receptive field (RF) properties of SOM neurons and parvalbumin-expressing inhibitory (PV) neurons genetically labeled in the mouse primary visual cortex. In contrast to PV neurons, SOM neurons exhibit broader spikes, lower spontaneous firing rates, smaller On/Off subfields, and broader ranges of basic RF properties such as On/Off segregation, orientation and direction tunings. Notably, the level of orientation and direction selectivity is comparable to that of excitatory neurons, from weakly-tuned to highly selective, whereas PV neurons are in general unselective. Strikingly, the evoked spiking responses of SOM cells are approximately 3- to 5-fold weaker and 20-25 ms delayed compared with those of PV neurons. The onset latency of the latter is consistent with that of inhibitory input to excitatory neurons. These functional differences between SOM and PV neurons exist in both layer 2/3 and 4. Our results suggest that SOM and PV neurons engage in cortical circuits in different manners: while PV neurons provide fast, strong but untuned feedforward inhibition to excitatory neurons, likely serving as a general gain control for the processing of ascending inputs, SOM neurons with their selective but delayed and weak inhibition may provide more specific gating of later arriving intracortical excitatory inputs on the distal dendrites.

Item Type: Paper
Subjects: 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
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:
Communities: CSHL labs > Huang lab
Depositing User: CSHL Librarian
Date: 27 October 2010
Date Deposited: 03 Oct 2011 19:45
Last Modified: 10 May 2013 15:57
PMCID: PMC3001391
Related URLs:
URI: https://repository.cshl.edu/id/eprint/15470

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