Biology subjects

Üstüner, C.

Publications and source records attributed to Üstüner, C..

2 recordsLinked to original sources

bioRxiv2026

Locomotion-invariant prefrontal-thalamic goal states organize spatially aligned episode-specific hippocampal maps

Animals repeatedly traverse the same environment to pursue different goals, yet the hippocampus must preserve a stable spatial map while keeping individual episodes distinct. Here we show that, when animals navigate the same maze under different goal configurations, hippocampal CA1 segregates navigation episodes by encoding goal state along a population dimension orthogonal to the spatial coding subspace, rather than by reorganizing spatial representations themselves, allowing episode-specific maps to remain spatially aligned. This goal-state signal is supplied by a prefrontal-thalamic pathway, in which population activity in medial prefrontal cortex and nucleus reuniens forms persistent representations across locomotion and immobility and is reliably reinstated when previously experienced goal configurations recur. Silencing the nucleus reuniens selectively abolishes CA1 goal-state coding by disrupting goal-axis separation and goal-biased pre-navigation spike sequences while sparing spatial coding. Together, these findings identify a circuit- and population-level mechanism that enables episode-specific hippocampal representations to coexist within spatially consistent maps independent of locomotor state, linking internal goal states to navigation and planning.

neuroscience↗

bioRxiv2025

The orbitofrontal cortex forms a context-generalized spatial schema that preserves topology and distance

Flexible and efficient navigation requires the brain to construct maps that are both topological, preserving the relationships between locations, and schematic, enabling generalization across environments. Although spatial maps in the hippocampus (HPC) and medial entorhinal cortex (MEC) have been extensively studied, they remap almost orthogonally across environments even during identical behaviors, raising the question of how animals maintain consistent navigation strategies across spatial contexts. Here, we identify a novel spatial map in the orbitofrontal cortex (OFC) that encodes navigational targets with distinct neural representations while preserving their topological order and relative distances by scaling to physical path lengths. Remarkably, OFC maps remained stable when animals performed the same navigation task across rooms and maze geometries, in stark contrast to the pronounced remapping observed in HPC and MEC. Moreover, OFC maps persisted after HPC or MEC lesions, demonstrating an independent spatial mapping system. These findings reveal a task-relevant topological schema in the OFC that uniquely supports flexible context-invariant navigation, expanding the brains spatial mapping repertoire beyond the hippocampal-entorhinal system.

neuroscience↗