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Updated: Jun 2, 2026
Tuning in the Hippocampal Theta Band In Vitro: Methodologies for Recording from the Isolated Rodent Septohippocampal Circuit
Published on: August 2, 2017
Reduction of theta rhythm dissociates grid cell spatial periodicity from directional tuning
Mark P Brandon1, Andrew R Bogaard, Christopher P Libby
1Center for Memory and Brain, Department of Psychology, Graduate Program for Neuroscience, Boston University, 2 Cummington Street, Boston, MA 02215, USA. markpb68@bu.edu
Abstract:
Grid cells recorded in the medial entorhinal cortex of freely moving rats exhibit firing at regular spatial locations and temporal modulation with theta rhythm oscillations (4 to 11 hertz). We analyzed grid cell spatial coding during reduction of network theta rhythm oscillations caused by medial septum (MS) inactivation with muscimol. During MS inactivation, grid cells lost their spatial periodicity, whereas head-direction cells maintained their selectivity. Conjunctive grid-by-head-direction cells lost grid cell spatial periodicity but retained head-direction specificity. All cells showed reduced rhythmicity in autocorrelations and cross-correlations. This supports the hypothesis that spatial coding by grid cells requires theta oscillations, and dissociates the mechanisms underlying the generation of entorhinal grid cell periodicity and head-direction selectivity.
