It has already been known that CA2 specializes in social memory, the ability to memorize meetings with others. As a result of this research, published in Nature magazine, because CA2 dysfunction has been implicated in psychiatric illnesses such as schizophrenia and bipolar disorder, these results provide additional support that can contribute to changing the CA2 function to abnormal social behaviors associated with these illnesses.
"People and mice are social creatures, both are engaged in learning and inborn social interactions that sometimes strengthen cooperation and sometimes lead to competition for partners, food and domination." As the brain mediates these conflicting impulses, the question was disturbing, "recalls Steven A. Siegelbaum, lead author of the study.
Although much of the hippocampus knows about it, the small size of the CA2 along with its inaccessible space scattered between larger and adjacent areas causes it to be a "challenge" to study. But in 2014, Siegelbaum's laboratory developed a genetic approach to activating or deactivating CA2 and found that this area is essential for social memory.
As a first step in determining whether CA2 can regulate other social behaviors, scientists have researched areas of the brain that receive information about CA2. They have found that this area sends a strong link to the side partition, a brain area that plays an important role in reducing violence. In fact, classic and more recent studies have shown that brain lesions of the side septum in several species, including humans, support hyperaesthesia.
CA2 and SIDE SIDE BRAIN
To find out whether the link between CA2 and the side divider is something else, the researchers temporarily turned off the CA2 on the mice that lived alone in the cage. Later they introduced the intruder into the cage and watched their behavior. When CA2 was off, there was a significant decrease in the tendency of the mouse to attack compared to what would normally occur. This difference indicates that CA2 normally acts to control aggressive behavior, besides regulating social memory.
"But why is the brain that controls memory also regulates aggression?" One footprint comes from the fact that male mice develop a social hierarchy when they live together, the dominant alpha male being the head of this hierarchy, followed by a succession of increasingly submissive men. When a new mouse is inserted into the colony, a foreigner and other mice struggle until the social hierarchy is restored, "the scientists explain.
According to their findings, a hormone called vasopressin may also be part of this phenomenon. When released into the brain, it regulates a number of social behaviors, so the team asked if vasopressin can help determine whether the mouse decides to attack. "The capability of CA2 cells to effectively activate the side septum is greatly increased when vasopressin is released in the lateral bulkhead," says Siegelbaum.
Because vasopressin levels are changed in people with schizophrenia and autism, scientists are hoping to further investigate whether these disorders are associated with CA2 dysfunction. In 2016, Siegelbaum and Zuckerman Institute chief Joseph Gogos found that mice carrying a human mutation associated with schizophrenia had dysfunctional CA2. This has provided prominent evidence that social memory deficits, a key feature of schizophrenia, may originate in CA2.
"People with schizophrenia have a wide range of behavioral disorders, including impaired social memory and altered levels of aggression, could it be the result of a loss or change in CA2 activity? Can these deficits alleviate by artificially increasing CA2 activity? research and research of others hope to be revealed, "concludes the scientist.
Information from Europa Press