Researchers at the University of Bonn have provided new understanding into how the human brain creates and accesses memories. This work, published in Nature Communications, focused on individual nerve cells (neurons) in people with a specific brain condition, revealing that these cells operate according to an internal rhythm.
Neurons are the basic building blocks of the brain, transmitting electrical and chemical signals. Electrical oscillations, or brain waves, are rhythmic patterns of electrical activity in the brain. The study observed that the activity of these nerve cells is connected to brain waves that occur one to ten times per second, similar to musicians following a shared beat. This connection means that nerve cells tend to become active at specific moments within these brain waves, a phenomenon called theta-phase locking.
The Brain's rhythmic memory processing
The researchers observed this close relationship between nerve cells and brain waves during both the learning and remembering of new information. This activity was particularly noticeable in the medial temporal lobe, a brain area vital for forming and storing conscious memories of facts and events.
However, the investigation into remembering locations in space showed that while theta-phase locking was present during memory formation, its strength did not by itself predict whether a memory would be successfully recalled later. This suggests that theta-phase locking is a common feature of our memory system but isn't the only factor determining if we can remember something.
Interestingly, while many nerve cells kept their preferred timing within the brain wave, some changed their timing when shifting from learning to remembering. This supports the theory that our brain can separate learning and retrieval processes within a brain wave, similar to members of an orchestra who start playing at different times in a piece of music. The insights gained from this study, which was possible by studying individuals with epilepsy who had temporary electrodes placed in their brains for diagnostic purposes, could eventually help scientists better understand and treat memory problems.