Place field dynamics in retrosplenial cortex compared to hippocampus.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• The neural mechanisms of memory encoding, storage, and updating in cortical networks remain largely unknown.
• Retrosplenial cortex (RSC) neurons exhibit position-correlated activity (PCCs) during navigation, with most requiring an intact hippocampus for formation but surviving its damage.

Purpose of the Study:

• To investigate whether PCCs in the RSC and hippocampus (CA1) remapping and spatial tuning develop in parallel or sequentially.
• To compare the spatial properties of PCCs in RSC and CA1 in response to novel environments.

Main Methods:

• Two-photon calcium imaging was used to record neuronal activity in the RSC or CA1 of mice navigating virtual reality (VR) linear tracks.
• Analysis focused on global remapping, tuning development dynamics, and place field expansion in familiar and novel contexts.

Main Results:

• RSC PCCs exhibited global remapping dynamics similar to CA1 when introduced to a novel context.
• Unlike CA1, RSC place fields did not show expansion in either familiar or novel environments.
• Place field shift and expansion were found to be exclusive to the hippocampus.

Conclusions:

• While RSC and CA1 share properties of global remapping, place field expansion is a distinct hippocampal mechanism.
• RSC place specificity may not be directly inherited from the hippocampus, or hippocampal influence is restricted to specific theta rhythm phases.