Parvalbumin interneurons provide grid cell-driven recurrent inhibition in the medial entorhinal cortex.
Grid cells in the medial entorhinal cortex (MEC) generate metric spatial representations. Recent attractor-network models suggest an essential role for GABAergic interneurons in the emergence of the grid-cell firing pattern through recurrent inhibition dependent on grid-cell phase. To test this hypothesis, we studied identified parvalbumin-expressing (PV(+)) interneurons that are the most likely candidate for providing this recurrent inhibition onto grid cells. Using optogenetics and tetrode recordings in mice, we found that PV(+) interneurons exhibited high firing rates, low spatial sparsity and no spatial periodicity. PV(+) interneurons inhibited all functionally defined cell types in the MEC and were in turn recruited preferentially by grid cells. To our surprise, we found that individual PV(+) interneurons received input from grid cells with various phases, which most likely accounts for the broadly tuned spatial firing activity of PV(+) interneurons. Our data argue against the notion that PV(+) interneurons provide phase-dependent recurrent inhibition and challenge recent attractor-network models of grid cells.
Department of Clinical Neurobiology at the Medical Faculty of Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany.
Christina
C
Buetfering
Department of Clinical Neurobiology at the Medical Faculty of Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany.
Kevin
K
Allen
Department of Clinical Neurobiology at the Medical Faculty of Heidelberg University and German Cancer Research Center (DKFZ), Heidelberg, Germany.
Hannah
H
Monyer
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D000075402:Channelrhodopsins; D000229:Dependovirus / Q000235:genetics; D018728:Entorhinal Cortex / Q000166:cytology*; D006801:Humans; D007395:Interneurons / Q000145:classification / Q000502:physiology*; D007834:Lasers; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D008845:Microinjections; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D010320:Parvalbumins / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013826:Theta Rhythm / Q000502:physiology; D014161:Transduction, Genetic; D000097573:Red Fluorescent Protein
D000075402:Channelrhodopsins; D008164:Luminescent Proteins; D010320:Parvalbumins; D000097573:Red Fluorescent Protein