Parvalbumin and Somatostatin Interneurons Control Different Space-Coding Networks in the Medial Entorhinal Cortex

Summary

The medial entorhinal cortex (MEC) contains several discrete classes of GABAergic interneurons, but their specific contributions to spatial pattern formation in this area remain elusive. We employed a pharmacogenetic approach to silence either parvalbumin (PV)- or somatostatin (SOM)-expressing interneurons while MEC cells were recorded in freely moving mice. PV-cell silencing antagonized the hexagonally patterned spatial selectivity of grid cells, especially in layer II of MEC. The impairment was accompanied by reduced speed modulation in colocalized speed cells. Silencing SOM cells, in contrast, had no impact on grid cells or speed cells but instead decreased the spatial selectivity of cells with discrete aperiodic firing fields. Border cells and head direction cells were not affected by either intervention. The findings point to distinct roles for PV and SOM interneurons in the local dynamics underlying periodic and aperiodic firing in spatially modulated cells of the MEC.

Video Abstract

Graphical Abstract

Highlights

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  Parvalbumin (PV) interneurons maintain spatially periodic firing in grid cells

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  PV interneurons are necessary for speed tuning in entorhinal speed cells

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  Somatostatin (SOM) interneurons maintain selectivity of aperiodic spatial cells

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  PV and SOM cells regulate discrete subsets of spatially tuned entorhinal cell types

Abstract

Two distinct sub-classes of inhibitory interneurons modulate different forms of spatial representation in the medial entorhinal cortex.