An important mechanism through which the brain goes from recalling an old memory to memorising a new, incoming one has been identified in a new study published in the journal Neuron. The findings are expected to provide invaluable information on cellular causes of dementia.
Conducted by scientists from the University of Bonn and the German Center for Neurodegenerative Diseases (DZNE), the study highlights new events happening in the brain when it comes to memory.
The region of the brain controlling memory is called the hippocampus: the new memories you make are stored there. The hippocampus also retrieves this saved information from their compartments as required. The researchers of the study describe it as a transport junction as it monitors inflowing new memories and stored ones. How does it manage the opposing flows?
According to the researchers, a “memory traffic policeman” exists to regulate the two-way flow of memory: the hippocampal astrocytes.
The role of astrocytes has remained elusive to scientists in the past. It is to be noted that they are not nerve cells, but, are rather what are called glial cells. It was previously thought that astrocytes only provided mechanical support to neurones, but then, other research revealed it could release or remove neurotransmitters. Later, its role in central memory processes was discovered. However, the mechanism behind this remained unknown. The new study is, therefore, invaluable in shedding light on their importance.
The researchers explain that the role of astrocytes is to make of the new memories a priority when they are triggered by a neurotransmitter called acetylcholine . The brain goes into memorisation mode as the retrieved memories are made to wait. It is the first time that the effect of acetylcholine pertaining to astrocytes has been documented. Author Milan Pabst explains that they have been able to demonstrate that the neurotransmitter stimulates the astrocytes, and the latter, in turn, release transmitter glutamate which activates inhibitory nerve cells which then act as inhibitor to a pathway involved in retrieving stored memories.
This study also contains indications that the regulated release of acetylcholine is disrupted in the brains of Alzheimer’s patients. If researchers are able to ascertain this, they might find new ways of fighting dementia related to the disease.