A Two-Dimensional Grid-Cell Code for Three-Dimensional Navigation in Freely Flying Bats.

Area of Science:

• Neuroscience
• Cognitive Science
• Animal Behavior

Background:

• Spatial navigation relies on neural circuits, with grid cells in the medial entorhinal cortex proposed to provide self-location signals via toroidal attractor dynamics in 2D environments.
• However, grid cell periodicity is lost during 3D movement, and the preservation of toroidal attractors and their role in 3D navigation across species remain unclear.

Purpose of the Study:

• To investigate whether a toroidal attractor is preserved at the ensemble level in the medial entorhinal cortex of freely flying bats.
• To understand how a 2D neural code could support navigation in a 3D environment.

Main Methods:

• Performed large-scale, wireless neural recordings from the medial entorhinal cortex of freely flying bats during spontaneous aerial foraging.
• Analyzed grid cell firing patterns and ensemble topological signatures.
• Correlated neural activity with behavioral analyses of flight paths in natural and laboratory settings.

Main Results:

• Grid cells exhibited robust periodic firing during structured flight trajectories in bats.
• Co-modular grid cell ensembles displayed topological signatures consistent with a 2D toroidal manifold.
• Bat flight paths were organized along 2D planes, aligning with the observed 2D neural code.

Conclusions:

• A 2D toroidal neural code is preserved in the bat medial entorhinal cortex during 3D navigation.
• This 2D code aligns with behaviorally relevant 2D planes of motion, offering a parsimonious solution for spatial orientation in a 3D world.