Key findings
- Perineuronal nets (PNNs) help stabilise brain activity needed for memory recall
- Removing PNNs disrupts communication between the hippocampus and retrosplenial cortex
- Loss of PNNs impairs spatial memory performance and weakens brain rhythms critical for coordination
Researchers from UQ’s Queensland Brain Institute have shown how microscopic structures in the brain’s retrosplenial cortex (RSC) help the retrieval of memories.
Dr Matilde Balbi said the research focused on RSC as a key brain region that helps integrate information from the hippocampus to support spatial memory (our ability to remember places and navigate the world).
“We investigated what keeps these two regions, the RSC and the hippocampus, in sync to recall memories,” Dr Balbi said.
“Within the RSC, specialised inhibitory neurons act as timing regulators, ensuring that neural activity remains coordinated.
“These neurons are wrapped in mesh-like structures called perineuronal nets (PNNs), which provide stability and protection.
“Our work shows that PNNs are not just passive, structural supports but are crucial for maintaining the coordinated activity required for memory recall.”
To understand their role, researchers selectively removed PNNs from the RSC in animal models. This impaired their ability to recall spatial memories, and although neuronal activity increased, it became disorganised.
“We also saw that brain rhythms (gamma and theta oscillations and their coupling) essential for synchronising activity within and between brain regions were reduced,” Dr Balbi said.
The team found this disruption extended beyond the RSC. Communication with the hippocampus weakened as coupling between the two regions reduced and impaired functional connectivity between neurons occurred.
The results demonstrate PNNs are vital for the timing and coordination required for memory retrieval.
Understanding how this kind of coordinated signalling breaks down can help scientists better understand neurological conditions where memory is affected.
This research is published in Cell Reports.
