Neuroscientists discover interactions between brain waves and nerve cells during human memory processes

Spatial navigation and spatial memory play a central role in our lives. Without these abilities, we would have difficulty getting our bearings and it would be difficult to remember past events. However, the neural basis of spatial memory is far from fully understood.

A research group led by Professor Dr. Lukas Kunz, who recently joined the University Hospital Bonn (UKB), has gained new insights into this knowledge gap. In collaboration with scientists from New York and Freiburg, he discovered that different types of nerve cells activate together during spatial memory and are coordinated by brain waves (“ripples”).

These results have now been published in the journal Natural neuroscience.

Associative memory ensures that different pieces of information are linked together. “In the context of spatial memory, associative memory allows us to remember the location of certain objects in the spatial environment,” explains Professor Kunz, head of the cognitive and translational neuroscience research group at the Department of epileptology from UKB. He is also a member of the Transdisciplinary Research Area (TRA) Life & Health at the University of Bonn.

“For example, we can remember where in the house we put our keys.” However, in old age or in certain illnesses such as Alzheimer’s disease, this capacity is limited. “It is therefore important to continue research into the neural bases of different forms of human memory,” explains Professor Kunz. In the long term, this could contribute to the development of new therapies for memory disorders.

Nerve cells play an important role in associative memory

Nerve cells are active while information is retrieved from memory. To explore this phenomenon further, the researchers recorded the activity of individual nerve cells in the brains of epilepsy patients while they performed a memory task on the computer. “In a virtual world, test participants had to remember the location of different objects,” explains Professor Kunz.

The recordings showed that different types of nerve cells became active during this memory task. Some nerve cells reacted to certain objects, while other nerve cells reacted to certain places. The scientists observed that the interactions between these different types of nerve cells became stronger over time when test participants remembered the right object in the right place.

Brain waves occur simultaneously and coordinate nerve cells

In addition to place and object neurons, the researchers observed that hippocampal brain waves (“ripples”) also became active during the memory task and thus likely played a crucial role in the formation and retrieval of associative memories.

“The ripples could be important for the connection of different types of nerve cells and the formation of complex memories. It will be exciting to explore this idea further in future studies,” explains Professor Kunz. It will also be interesting in the future to study how memory performance is modulated when ripples are suppressed or even triggered, which will provide insight into the causal relevance of ripples.

Provided by University Hospital Bonn