Ripples in the brain play key role in forming complex memories

Spatial navigation and spatial memory play a central role in our lives. Without these abilities, we would hardly be able to find our way around our surroundings and would find it difficult to remember past events. However, the neuronal basis of spatial memory is far from being fully understood. A research group led by Prof. Dr. Lukas Kunz, who has recently joined the University Hospital Bonn (UKB), has gained new insights into this gap in knowledge. Together with scientists from New York and Freiburg, he has discovered that different types of nerve cells become active together during spatial memory and are coordinated by brain waves ("ripples"). The results have now been published in the journal "Nature Neuroscience".

Associative memory ensures 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," explains Prof. Kunz, research group leader for Cognitive and Translational Neuroscience at the Department of Epileptology at the 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". At older age or with in certain diseases such as Alzheimer's, however, this ability is limited. "It is therefore important to investigate that the neuronal basis of different forms of human memory is researched further," says Prof. Kunz. In the long term, this could help in the development of new therapies for memory impairments.

Nerve cells play an important role in associative memory

Nerve cells are active while information is being linked and retrieved from memory. To further investigate this phenomenon, the research groupers recorded the activity of individual nerve cells in the brains of epilepsy patients while they were performing a memory task on the computer. "In a virtual world, the test subjects had were asked to remember the locations of various objects," explains Prof. Kunz.

The recordings showed that different types of nerve cells become became active during such a memory task. Some nerve cells reacted in particular responded to certain objects, while other nerve cells reacted activated in response to certain locations. The scientists observed that the exchange interactions between these different types of nerve cells became stronger over time increased when the test subjects participants remembered the right object in the right place and the right object.

Brain waves occur simultaneously coordinate the nerve cells

At the same time, in addition to place and object neurons, the researchers observed that in addition to place and object neurons, hippocampal brain waves ("ripples") that also become active occurred during the memory task, and thus 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 further in other tasks in future studies."

Prof. Dr. Lukas Kunz, research group leader for Cognitive and Translational Neuroscience at the Department of Epileptology at the UKB

In addition, it could also be interesting in the future to see study what happens show memory performance is modulated when ripples are suppressed or even triggered, providing insights into the causal relevance of ripples.

Prof. Kunz intends to continue the findings that he gained with his colleagues at Columbia University's School of Engineering and Applied Science in New York and the University Hospital of Freiburg at the Bonn siteUniversity Hospital Bonn. "The Department of Epileptology at the UKB is well-known for its excellent brain research. In particular, there is department has the unique opportunity to record the activity of individual nerve cells in the human brain in the video EEG monitoring unit -, which is the heart of every epilepsy center. This provides exciting insights into the functioning of the human brain, which is only possible at a few research centers worldwide," describes Prof. Kunz. At the same time, in his interdisciplinary research, he relies builds on close exchange with other researchers and medical doctors, which is very important and essential for the development of new research ideas.