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Inhibits learning, increases forgetfulness

Researchers have identified a protein that plays a key role in erasing memories

Merit Sloin

Two years ago, neuroscientist Eric Kendall won the Nobel Prize for his contribution to deciphering
The molecular mechanisms of the learning and memory processes. Kendall did his research
On a shellless marine snail called Aplazia. But the learning and memory processes he discovered
In the aplasia there are, as it turned out later, also in vertebrates.

Kendall showed that memory is associated with changes in the efficiency of communication between nerve cells.
These changes take place mainly in synapses - the nerve junctions where they meet
two nerve cells. A neurotransmitter (neurotransmitter) is released from the end of one nerve cell that binds
to the receptors in the second cell, and these trigger an electrical voltage in this cell. while learning increases
The amount of neurotransmitter that is released and absorbed, and it gradually decreases over time
the oblivion

What causes the increased release of the neurotransmitter in the synapse? Kendall found that learning
Activates in the nerve cells an array of molecules that cause a temporary change in proteins
involved in neural communication. Common to these changes is a chemical process called
Phosphorylation, where enzymes attach a phosphorus molecule to certain proteins. also exists
Reverse process, where other enzymes remove the phosphorus molecule. the proteins
The phosphorylated ones cause changes in the synapses, which speed up the transmission of nerve signals;
On the other hand, removing the phosphorus stops the process.

It is possible to distinguish between two forms of memory (learning is the process of creating memory):
Short-term memory, which lasts hours, and long-term memory, which lasts days, weeks
and years In long-term memory, phosphorylated proteins enter the cell nucleus
and activate genes. The products of the genes cause structural changes in the nerve cell. the cell
Grows new branches that speed up communication with other nerve cells, and are formed
Large synapses that illustrate the passage of nerve signals. Deleting these changes
Slower, and the memory lasts for a long time.

A research group from the Swiss Federal Institute of Technology in Zurich, led by David Geno,
has now taken another step towards deciphering the mechanisms of learning and memory. the researchers,
whose research was published last week in the journal "Nature" reported that they had found a protein
responsible for forgetting.

The Swiss researchers relied on previous studies that hinted at the existence of a factor
Molecular that reduces the efficiency of neural communication and in this way inhibits learning processes.
The researchers suspected that this factor belongs to the family of molecules involved in adhesion or removal
of a phosphorus molecule, and chose to test one of these molecules - an enzyme named PP1
In order to test the role of PP1, they created a strain of mice that produce the inhibitory protein
The researchers could activate and deactivate the inhibitory protein PP1 activity
as they wish.

The researchers trained the mice to recognize new objects. One group learned this
gradually and at regular intervals; The second group studied in the center. after the
The study tested the memory of the two groups based on their behavior, and the degree was measured
The activity of PP1 in the brain.

In the mice that studied at the learning center, the learning was not effective: they had difficulty recognizing the objects.
Also, a high activity of PP1 was found in their brains, which apparently affected the efficiency
the learning. In animals where the learning was done gradually and in time intervals the learning was effective
And the activity of PP1 was low. But more than that: when the researchers activated the protein
The PP1 inhibitor during focused learning improved learning and the mice reached the same
Results like the mice that gradually learned. PP1 thus inhibits the formation of memory when
concentrated study.

The next question the researchers wanted to test was whether PP1 accelerates the processes of forgetting after
that the memory is created. They trained mice to find a platform that was hidden inside
pool. For some time after training the mice were able to find the platform, but
Over time their memory faded and their performance deteriorated. When the investigators detained the
PP1 activity in some of the mice previously trained to find the platform, it turned out
that these mice remembered how to reach the platform 4 to 6 weeks after the mice
The others forgot it.

Encouraged by this finding, the researchers tested whether PP1 is also involved in the forgetting process that occurs
when aging. With aging, learning becomes more difficult and forgetfulness increases. Explanation is that the reason
This is irreversible changes that occur in the nerve cells in the brain. in order to check it
The researchers conducted the platform test for adult mice; They came to know that delay
PP1 improves their learning and prevents memory deterioration. According to the researchers,
The results of the experiment indicate that forgetfulness in old age does not necessarily arise
from irreversible changes in the nerve cells, but from the active involvement of PP1. This discovery
Opens possibilities for drug treatment to improve memory in the elderly.

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