Memory also involves brain waves

A research group led by Prof. Lukas Kunz, research group leader for Cognitive and Translational Neuroscience at the Clinic and Polyclinic for Epileptology at the University Hospital Bonn (UKB), explains that spatial navigation and spatial memory are crucial in our daily lives. Without these abilities, it would be challenging to navigate our surroundings and recall past events.

The study published in the journal Nature Neuroscience, states that different types of nerve cells become active together during spatial memory and are coordinated by brain waves ("ripples").

Associative memory allows that different pieces of information are linked together. "In the context of spatial memory, associative memory enables us to remember the locations of certain objects in the spatial environment," said Prof. Kunz. "For example, we can remember where in the house we put our keys. At older age or in certain diseases such as Alzheimer's, however, this ability is limited. It is therefore important to investigate the neuronal basis of different forms of human memory.”

Nerve cells are active while information is retrieved from memory. To investigate this phenomenon, the researchers recorded the activity of individual nerve cells in epilepsy patients performing a memory task. "In a virtual world, the participants were asked to remember the locations of different objects.”

The recordings showed that different types of nerve cells became active during this memory task. Some nerve cells responded to certain objects, while other nerve cells activated in response to certain locations and interactions between the different types of nerve cells became stronger over time when participants remembered the right object in the right place.

In addition to place and object neurons, the researchers observed hippocampal brain waves ("ripples") that also occurred during the memory task, presumably playing a crucial role in the formation and retrieval of associative memories. "Ripples could be important for the connection of different types of nerve cells and the formation of complex memories. It will be exciting to further investigate this idea in future studies. It will also be interesting to study how memory performance is modulated when ripples are suppressed or triggered, providing insights into the causal relevance of ripples.” concluded Prof. Kunz

Reference: DOI: 10.1038/s41593-023-01550-x