Dynamics of the Hippocampal Ensemble Code for Space

TLDR

Parallel recording methods enable the study of neuronal interaction dynamics during unique behavioral events. Ensemble recordings of 73–148 hippocampal neurons accurately predicted rat movement, confirming an ensemble location code that initially weakens but quickly strengthens in novel environments, while inhibitory cell suppression and minimal interference with familiar codes suggest synaptic plasticity supports rapid spatial learning.

Abstract

Ensemble recordings of 73 to 148 rat hippocampal neurons were used to predict accurately the animals' movement through their environment, which confirms that the hippocampus transmits an ensemble code for location. In a novel space, the ensemble code was initially less robust but improved rapidly with exploration. During this period, the activity of many inhibitory cells was suppressed, which suggests that new spatial information creates conditions in the hippocampal circuitry that are conducive to the synaptic modification presumed to be involved in learning. Development of a new population code for a novel environment did not substantially alter the code for a familiar one, which suggests that the interference between the two spatial representations was very small. The parallel recording methods outlined here make possible the study of the dynamics of neuronal interactions during unique behavioral events.