Study Reveals How Bat Brains Use 2D Grid Cells to Navigate 3D Space
Researchers recording neural activity in freely flying bats found that grid cells in the medial entorhinal cortex maintain a two-dimensional periodic firing code even during three-dimensional aerial navigation. Prior studies had reported a breakdown of grid-cell periodicity in 3D environments, raising questions about how the brain handles volumetric space. The findings suggest the brain resolves this by aligning its 2D spatial code with the natural planar structure of actual flight paths, offering a parsimonious solution to a longstanding neuroscience puzzle.
A new preprint study published on bioRxiv used large-scale wireless neural recordings from the medial entorhinal cortex of freely flying bats to investigate how grid cells — neurons known to provide periodic, map-like representations of space — function during genuine three-dimensional movement. The researchers found that grid cells fired robustly and periodically during structured flight, and that ensembles of co-modular grid cells displayed topological signatures consistent with a two-dimensional toroidal manifold, a geometric structure previously theorized to underlie grid-cell computation. Crucially, behavioral analyses of bats both in the wild and in laboratory settings revealed that individual flight trajectories are naturally organized along two-dimensional planes of motion rather than being truly volumetric. This planar structure in behavior provides a natural substrate for the brain's 2D spatial code: toroidal phase progressions along flights matched plane-wave patterns on the movement plane, and single-cell firing was well described by a hexagonal lattice on that same plane. The study proposes that rather than evolving a fully three-dimensional neural code, the brain exploits the inherent planarity of real-world movement to make a 2D circuit architecture sufficient for navigating 3D space.
What's missing
As a preprint, this work has not yet undergone formal peer review. It remains an open question whether the same planar-flight explanation generalizes to animals with more volumetric movement patterns, such as fish or insects. The causal role of toroidal dynamics in navigation behavior has not been experimentally tested.
What different sources said
- bioRxivCenter
A Two-Dimensional Grid-Cell Code for Three-Dimensional Navigation in Freely Flying Bats
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.