Robust perisomatic GABAergic self-innervation inhibits basket cells in the human and mouse supragranular neocortex
Abstract
Inhibitory autapses are self-innervating synaptic connections in GABAergic interneurons in the brain. Autapses in neocortical layers have not been systematically investigated, and their function in different mammalian species and specific interneuron types is poorly known. We investigated GABAergic parvalbumin-expressing basket cells (pvBCs) in layer 2/3 (L2/3) in human neocortical tissue resected in deep-brain surgery, and in mice as control. Most pvBCs showed robust GABAAR-mediated self-innervation in both species, but autapses were rare in nonfast-spiking GABAergic interneurons. Light- and electron microscopy analyses revealed pvBC axons innervating their own soma and proximal dendrites. GABAergic self-inhibition conductance was similar in human and mouse pvBCs and comparable to that of synapses from pvBCs to other L2/3 neurons. Autaptic conductance prolonged somatic inhibition in pvBCs after a spike and inhibited repetitive firing. Perisomatic autaptic inhibition is common in both human and mouse pvBCs of supragranular neocortex, where they efficiently control discharge of the pvBCs.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting files.
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Funding
NKFIH (National Brain Research Programme)
- Viktor Szegedi
- Melinda Paizs
- Karri Lamsa
ERC (INTERIMPACT)
- Gabor Tamas
Hungarian Academy of Sciences
- Viktor Szegedi
- Gábor Molnár
University of Szeged Open Access Fund (4373)
- Viktor Szegedi
- Karri Lamsa
Eotvos Lorand Research Network
- Gabor Tamas
National Research, Development and Innovation Office of Hungary (GINOP-2.3.2-15-2016-00018)
- Gabor Tamas
National Research, Development and Innovation Office (OTKA K128863)
- Gábor Molnár
- Gabor Tamas
- Karri Lamsa
Ministry of Human Capacities Hungary (20391-3/2018/FEKUSTRAT)
- Gabor Tamas
- Karri Lamsa
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All procedures were performed with the approval of theUniversity of Szeged (no. I-74-8/2016) and in accordance withthe Guide for the Care and Use of Laboratory Animals (2011)(http://grants.nih.gov/grants/olaw/guide-for-the-care-and-use-oflaboratory-animals.pdf).
Human subjects: All procedures were performed according to the Declaration of Helsinki with the approval of the University of Szeged Ethical Committee and Regional Human Investigation Review Board (ref. 75/2014). For all human tissue material, written consent was obtained from patients prior to surgery. Tissue obtained from underage patients was provided with agreement from a parent or guardian.
Copyright
© 2020, Szegedi et al.
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.
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