Hippocampal-medial prefrontal cortex network dynamics predict performance during retrieval in a context-guided object...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• Episodic memory recall involves complex interactions between multiple brain regions.
• The hippocampus (HPC) is thought to trigger memory recall via medial prefrontal cortex (mPFC) activation, but mechanisms are unclear.
• Coordinated activity between the HPC and mPFC during memory retrieval is not well understood.

Purpose of the Study:

• To investigate the neural mechanisms underlying memory recall, focusing on the interaction between the ventral hippocampus (vHPC) and mPFC.
• To explore how coordinated brain activity and neuronal ensembles in the mPFC contribute to object-in-context (OIC) memory retrieval.

Main Methods:

• Electrophysiological recordings were performed in behaving rats during the OIC memory task.
• Analysis included local field potential (LFP) synchronization (coherence, phase locking, theta amplitude correlation) between vHPC and mPFC.
• Neuronal ensembles in the mPFC encoding object-context associations were identified.

Main Results:

• An increase in vHPC-mPFC LFP synchronization in the theta range was observed when rats explored contextually mismatched objects.
• Specific neuronal ensembles in the mPFC were found to encode object-context associations.
• Increased vHPC-mPFC synchronization and mPFC neuronal activity predicting incongruent object recognition correlated with task performance.

Conclusions:

• Changes in vHPC-mPFC synchronization are implicated in the recall of past events.
• mPFC neuronal ensembles encoding specific object-context associations play a role in memory retrieval.
• These findings elucidate the coordinated neural dynamics supporting memory recall.