Glial brain cells: the backbone for memory formation

Role of dendritic integration of synaptic activity

When we visit any place, we store the combination of features of that specific place. For instance, a gnarled tree has numerous characteristics that make it unmistakable as a whole. So, when we encounter the interplay of trees at another time, our brain cells recognize it instantly: We remember that we’ve been here before. 

This is only made possible by the mechanisms present in the brain known as dendritic integration of synaptic activity. According to Prof. Dr. Christian Henneberger of the Institute of Cellular Neuroscience at the University Hospital Bonn, the so-called astrocytes or astroglial cells play a crucial part in this integration. They control how responsive neurons are to a particular set of characteristics.

Spatial memory – one million place cells 

In an in-depth investigation, scientists from the Collaborative Research Center 1089 and Transdisciplinary Research Area “Life & Health” at the University of Bonn took a closer look into neurons located in mice hippocampus. This region is famously renowned for its memory processes, especially spatial memory, which houses over one million “place cells” that react to different environmental elements individually.

Place cells are genuinely fascinating, with dendrites resembling a crown of branches waiting to be triggered.  Dr. Kirsten Bohmbach explained that when many contacts, known as synapses, fire in unison simultaneously and produce an electrical pulse through these extensions called “dendritic spikes,” we experience what is referred to as “dendritic integration.”

It is a process where any strong enough signal that passes down toward the cell body triggers another voltage burst or action potential, carrying information about its specific location directly into our senses!

When mice first arrive in a new environment, their cells generate an extraordinary rhythm: 5 to 10 voltage pulses per second. This special electrical pattern causes neurons to release specific messenger substances. The substances can be detected by astrocytes through sensors which then result in the production of D-serine – a substance key for knowledge acquisition and memory formation. Place cells orchestrate this remarkable process as they oscillate with amazing speed and precision.

A new insight – how our memory works 

Bohmbach explained – the D-serine migrates to the dendrite of our place cells. At this place, it makes sure that the dendritic spikes can be developed easily and are stronger than ever. When mice explore their surroundings, they instinctively focus on the details of each space to be able to recall it easily. It is similar to a cab driver attentively navigating unfamiliar roads and memorizing bustling landmarks while his passenger has already lost interest in what’s outside the vehicle – although different areas of attention are certainly at play here!

Henneberger said that the mice are less likely to recognize familiar places when we inhibit the assistance provided by astrocytes in mice. However, this outcome is not applicable to locations that are specifically relevant. For instance, the places that pose a potential danger. 

In this way, researchers uncovered the mechanism that regulates how and when location information is stored in our memory – offering both insights into its functioning as well as paving the way for further understanding of memory disorders. 

This breakthrough was only made possible through extensive collaboration between multiple campuses – specifically thanks to Prof. Dr. Heinz Beck’s laboratory at IEECR- Institute of Experimental Epileptology & Cognitive Research involving Nicola Masala & Thoralf Opitz!

So we can say glial brain cells act as the backbone for memory formation within the human brain and play a pivotal role in helping us recall moments from both distant and recent history.