Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
J Neurosci. 2010 Oct 27;30(43):14371-9. doi: 10.1523/JNEUROSCI.3248-10.2010.

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

Author information

  • 1Zilkha Neurogenetic Institute, Departments of Cell and Neurobiology and Biophysics and Physiology, and Graduate Programs, University of Southern California, Los Angeles, California 90089, and Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724.

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 ∼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.

PMID:
20980594
[PubMed - indexed for MEDLINE]
PMCID:
PMC3001391
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central Icon for USC Health Sciences Libraries
    Loading ...
    Write to the Help Desk