Grid cell co-activity patterns during sleep reflect spatial overlap of grid fields during active behaviors

Area of Science:

• Neuroscience
• Computational Neuroscience
• Spatial Navigation

Background:

• Grid cells in the medial entorhinal cortex are crucial for spatial navigation.
• Continuous-attractor network models propose recurrent connectivity shapes grid cell activity.
• Stable spatial tuning offsets between grid cells suggest underlying network organization.

Purpose of the Study:

• To investigate if grid cell relationships, predicted by attractor models, persist during sleep.
• To determine if internal network connectivity, rather than sensory input, drives grid cell patterns across behavioral states.

Main Methods:

• Recorded ensembles of grid cells in the medial entorhinal cortex during active exploration and overnight sleep (REM and NREM).
• Analyzed spike-time correlations between grid cell pairs and collectively.
• Examined the influence of theta oscillations and hippocampal CA1 activity.

Main Results:

• Preserved patterns of spike-time correlations were observed across waking and sleep states.
• These correlations reflected the stable spatial tuning offsets of grid cells during active exploration.
• The preservation of cell-cell relationships was independent of theta oscillations and CA1 activity.

Conclusions:

• Recurrent connectivity within the grid cell network is the primary driver of grid cell activity across behavioral states.
• Internal network dynamics, not external sensory inputs, maintain spatial representations during sleep.
• Supports attractor network models for grid cell function and spatial memory consolidation.