It happens to us all. We are listening to a playlist, watching a movie or our favorite TV show when our mind snaps. Something in that song, movie or show brought a memory, a bad one back to life. What is there to do about a bad memory? Is it even under our conscious control?
As it turns out, it is, but we need help from out physical body to forget something unpleasant. The act of forgetting something that makes us cry of sadness is not just a simple physchological exercise, or a series of them.
Enter atrocities. Perhaps you have never heard of them, but these brain cells are directly responsible for helping us forget.
Astrocytes help the selective erasure of memories, a type of erasure that is exacerbated in diseases such as Alzheimer’s and is related to memory loss, according to a study by scientists published by Nature Communications.
The study points out that astrocytes help to erase irrelevant memories and replace them with new events, weakening the synaptic connections between hippocampal neurons, a region of the brain involved in memory processes and cognitive flexibility, explains the Higher Education Center. Scientific Investigations (CSIC).
One of the most unique properties of the brain is its plasticity, which allows that when receiving new information that we want to retain, the neurons that transmit it reinforce its connections, which is the process known as synapsis.
However, synaptic connections can also weaken, a process that is necessary to erase information that is no longer relevant and replace it, so we remember where we left the car parked today but not where we did yesterday or last week.
This is explained by researchers who add that without this form of “selective erasure we would store a multitude of overlapping and contradictory memories in the brain”.
This form of selective erasure “is exacerbated in pathological situations, such as in Alzheimer’s disease, and is related to memory loss”, therefore understanding the mechanism that guides them “may be important to develop new therapeutic strategies” against the disease , adds the note.
Until now it had been assumed that neurons were solely responsible for remodeling their synaptic connections, both to reinforce them and to weaken them.
However, in recent years it has been shown that glia cells, of which astrocytes and other non-neuronal cells are part, also participate in synaptic communication.
Researchers have now discovered that astrocytes “act as intermediaries in the communication between neurons, to produce synaptic depression”.
The results of the researcher show that to weaken synapses, neurons activate calcium signals in astrocytes, which release glutamate, in a mechanism mediated by the p38a MAPK protein.
That released glutamate again stimulates the neurons, which triggers a cascade of molecular events that leads to the weakening of the synaptic connections.
The study demonstrates, through genetic manipulations in mice, that this mechanism is important to limit memory.
During the experiments, when the p38a MAPK gene was exclusively eliminated in the astrocytes, and not in the neurons of the hippocampus, there was an increase in long-term memory retention in the mice.
“These findings represent a conceptual change of the knowledge that we hd until now about the mechanisms that underlie this form of synaptic plasticity” and consolidate the idea that astrocytes play an integral role in the storage and elimination of information in the brain, ” concludes the study.