Border cells without theta rhythmicity in the medial prefrontal cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Spatial Navigation

Background:

• The medial prefrontal cortex (mPFC) is crucial for cognitive functions reliant on spatial awareness.
• Previous research has explored mPFC spatial tuning during memory tasks, but not during free exploration.

Purpose of the Study:

• To investigate spatial representations within the mPFC network during unconstrained foraging behavior.
• To characterize the properties of mPFC border cells and compare them to known border cells in the medial entorhinal cortex (MEC).

Main Methods:

• Recording neural activity from mPFC ensembles during spontaneous exploration in varied environments.
• Analyzing firing patterns to identify spatially tuned neuronal activity, specifically border representations.
• Assessing the stability and responsiveness of these representations to environmental changes and conditions like darkness.

Main Results:

• Discovery of geometric border or border-proximal representations in mPFC neural ensembles during exploration.
• Identification of mPFC border cells that fire along multiple walls, unlike MEC border cells typically firing along one.
• Demonstration that mPFC border cells are stable across different environments, shapes, and darkness, and can form new fields.
• Observation of minimal theta rhythmicity in mPFC border cells during spontaneous locomotion, contrasting with hippocampal theta entrainment.

Conclusions:

• The mPFC exhibits spatially modulated activity, contributing to cognitive functions requiring spatial context.
• mPFC border cells possess unique properties, suggesting distinct computational roles compared to MEC border cells.
• These findings highlight a broad spatial tuning property within cortical circuits, supporting local spatial computations.