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

Area of Science:

• Neuroscience
• Computational Neuroscience

Background:

• Grid cells in the medial entorhinal cortex exhibit hexagonal firing fields crucial for spatial navigation.
• Despite regular field structures, grid cell responses display considerable trial-to-trial variability, the origins of which remain unclear.

Purpose of the Study:

• To investigate the sources of trial-to-trial variability in grid cell firing.
• To characterize the phenomenon of
• missed
• firing fields using statistical zero-inflation models.

Main Methods:

• Analysis of grid cell spike trains from mice in open arenas and on linear tracks.
• Application of the statistical theory of zero inflation to quantify firing field variability.
• Examination of spatial realignment and trial-to-trial drift in grid cell ensembles.

Main Results:

• Grid cell firing fields are less anchored to specific spatial locations than previously assumed.
• A significant portion of grid cell variability stems from the dynamic nature of spatial representations.
• Grid cell fields exhibit correlated drift across trials, independent of environmental conditions or locomotion.

Conclusions:

• Ensembles of grid cells provide a more reliable encoding of relative spatial position compared to absolute position.
• Spatial realignment across trials enhances the precision and prominence of grid cell representations.