TY  - JOUR
AU  - Grosser, Sabine
AU  - Barreda, Federico J
AU  - Beed, Prateep Sanker
AU  - Schmitz, Dietmar
AU  - Booker, Sam A
AU  - Vida, Imre
TI  - Parvalbumin Interneurons Are Differentially Connected to Principal Cells in Inhibitory Feedback Microcircuits along the Dorsoventral Axis of the Medial Entorhinal Cortex.
JO  - eNeuro
VL  - 8
IS  - 1
SN  - 2373-2822
CY  - Washington, DC
PB  - Soc.
M1  - DZNE-2021-00797
SP  - ENEURO.0354-20.2020
PY  - 2021
AB  - The medial entorhinal cortex (mEC) shows a high degree of spatial tuning, predominantly grid cell activity, which is reliant on robust, dynamic inhibition provided by local interneurons (INs). In fact, feedback inhibitory microcircuits involving fast-spiking parvalbumin (PV) basket cells (BCs) are believed to contribute dominantly to the emergence of grid cell firing in principal cells (PrCs). However, the strength of PV BC-mediated inhibition onto PrCs is not uniform in this region, but high in the dorsal and weak in the ventral mEC. This is in good correlation with divergent grid field sizes, but the underlying morphologic and physiological mechanisms remain unknown. In this study, we examined PV BCs in layer (L)2/3 of the mEC characterizing their intrinsic physiology, morphology and synaptic connectivity in the juvenile rat. We show that while intrinsic physiology and morphology are broadly similar over the dorsoventral axis, PV BCs form more connections onto local PrCs in the dorsal mEC, independent of target cell type. In turn, the major PrC subtypes, pyramidal cell (PC) and stellate cell (SC), form connections onto PV BCs with lower, but equal probability. These data thus identify inhibitory connectivity as source of the gradient of inhibition, plausibly explaining divergent grid field formation along this dorsoventral axis of the mEC.
KW  - Action Potentials
KW  - Animals
KW  - Entorhinal Cortex: metabolism
KW  - Feedback
KW  - Interneurons: metabolism
KW  - Parvalbumins: metabolism
KW  - Pyramidal Cells: metabolism
KW  - Rats
KW  - GABAergic interneurons (Other)
KW  - entorhinal cortex (Other)
KW  - feedback inhibition (Other)
KW  - microcircuit (Other)
KW  - morphology (Other)
KW  - synapse (Other)
KW  - Parvalbumins (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:33531369
C2  - pmc:PMC8114875
DO  - DOI:10.1523/ENEURO.0354-20.2020
UR  - https://pub.dzne.de/record/155629
ER  -