Untethered firing fields and intermittent silences: Why grid-cell discharge is so variable

Nagele, Johannes; Herz, Andreas V. M. und Stemmler, Martin B. (February 2020): Untethered firing fields and intermittent silences: Why grid-cell discharge is so variable. In: Hippocampus, Vol. 30, No. 4: pp. 367-383

Abstract

Grid cells in medial entorhinal cortex are notoriously variable in their responses, despite the striking hexagonal arrangement of their spatial firing fields. Indeed, when the animal moves through a firing field, grid cells often fire much more vigorously than predicted or do not fire at all. The source of this trial‐to‐trial variability is not completely understood. By analyzing grid‐cell spike trains from mice running in open arenas and on linear tracks, we characterize the phenomenon of “missed” firing fields using the statistical theory of zero inflation. We find that one major cause of grid‐cell variability lies in the spatial representation itself: firing fields are not as strongly anchored to spatial location as the averaged grid suggests. In addition, grid fields from different cells drift together from trial to trial, regardless of whether the environment is real or virtual, or whether the animal moves in light or darkness. Spatial realignment across trials sharpens the grid representation, yielding firing fields that are more pronounced and significantly narrower. These findings indicate that ensembles of grid cells encode relative position more reliably than absolute position.

• Item Type: Journal article
• Form of publication: Publisher's Version
• Keywords: entorhinal cortex, excess variability, firing-field jitter and drift, grid cell, noise correlation, overdispersion, spatial navigation, trial-to-trial variability, tuning curve, zero inflation
• Faculties: Biology > Department Biology II; Biology > Department Biology II > Neurobiology
• Subjects: 500 Science > 570 Life sciences; biology
• ISSN: 1098-1063
• Annotation: Special Issue: Computational models of hippocampus and related structures‐Part I
• Language: English