Serotonin enhances excitability and gamma frequency temporal integration in mouse prefrontal fast-spiking interneurons

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Abstract

The medial prefrontal cortex plays a key role in higher order cognitive functions like decision making and social cognition. These complex behaviors emerge from the coordinated firing of prefrontal neurons. Fast-spiking interneurons (FSIs) control the timing of excitatory neuron firing via somatic inhibition and generate gamma (30-100 Hz) oscillations. Therefore, factors that regulate how FSIs respond to gamma-frequency input could affect both prefrontal circuit activity and behavior. Here, we show that serotonin (5HT), which is known to regulate gamma power, acts via 5HT2A receptors to suppress an inward-rectifying potassium conductance in FSIs. This leads to depolarization, increased input resistance, enhanced spiking, and slowed decay of excitatory post-synaptic potentials (EPSPs). Notably, we found that slowed EPSP decay preferentially enhanced temporal summation and firing elicited by gamma frequency inputs. These findings show how changes in passive membrane properties can affect not only neuronal excitability but also the temporal filtering of synaptic inputs.

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Jegath C Athilingam

Department of Psychiatry, University of California, San Francisco, San Francisco, United States

For correspondence
jiggy.athilingam@ucsf.edu

Competing interests
The authors declare that no competing interests exist.
Roy Ben-Shalom

Department of Neurology, University of California, San Francisco, San Francisco, United States

Competing interests
The authors declare that no competing interests exist.
Caroline M Keeshen

Department of Neurology, University of California, San Francisco, San Francisco, United States

Competing interests
The authors declare that no competing interests exist.
Vikaas Sohal

Department of Psychiatry, University of California, San Francisco, San Francisco, United States

For correspondence
vikaas.sohal@ucsf.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-2238-4186
Kevin Bender

Department of Neurology, University of California, San Francisco, San Francisco, United States

For correspondence
kevin.bender@ucsf.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-7084-1532

Funding

National Institute of Mental Health (NRSA F31 MH111219-01)

Jegath C Athilingam

National Institutes of Health (U01 MH105948)

Vikaas Sohal

National Institutes of Health (R01 DA035913)

Kevin Bender

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols (AN170116, AN129822-02F) of the University of California, San Francisco. All surgery was performed under isofluorane anesthesia, and every effort was made to minimize suffering.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.