The brain mechanisms that facilitate episodic memory

Using episodic memory to remember past holidays

A new study paper, co-authored by Dr Simon Hanslmayr, has suggested how opposing brain mechanisms might facilitate episodic memory. 

Episodic memory is used in everyday life, when engaging in mental time travel, for instance when we recall the restaurant where we had dinner last week or when we remember our last holidays. 

Although we recruit these mechanisms seemingly effortlessly, they rely on very complex interactions between distributed networks in the brain. 

Brain oscillations trigger synchronous firing of neurons and are one of the core brain mechanisms that orchestrate such complex interactions during episodic memory. 

However, in the past few years conflicting results have been reported as roughly half of the studies in this field highlight the role of synchronized brain oscillations, whereas the other half highlight the role of desynchronized oscillations. 

In this study, the research team describe a novel framework that unites these conflicting results and integrates the two opposing oscillatory behaviours, synchronization and desynchronization. 

Specifically, the study illustrates a simple model that shows that synchronization and desynchronization might reflect a division of labour between a hippocampal and a neocortical system, respectively. 

While synchronous oscillations in the hippocampus bind the different elements of a memory episode together, desynchronized activity in the cortex allows the brain to represent the different elements of the memory episode. This is a novel oscillatory framework that integrates synchronization and desynchronization mechanisms to explain how the two systems interact in the service of episodic memory and could be an important guide for future studies allowing the field to progress.

Reference:
Hanslmayr, Staresina, & Bowman (2016). Oscillations and Episodic Memory: Addressing the Synchronization/Desynchronization Conundrum. Trends in Neurosciences, 39 (1), 16-25.