Friend or foe? Brain area that controls social memory and aggression

on 03 January 2019
The brain's magic revealed

If you want a happy and productive life, you really need to manage psychological and oxidative stress and the anxiety that most often accompanies it. If you are looking for a solution to your stress, look no further; hypnotherapy is the answer you are looking for - Trust Me. . . . 

This research highlights the influence of a very small area of the hippocampus, CA2, albeit there are 4 such areas, CA1 - 4. It is interesting that when scientists turned off this area, the natural tendency of alpha male dominance (attack a potential threat), did not occur? Things that could affect such responses in our everyday life could be brain lesions, caused by accidents, viral infections and, in some instances, too much stress! While turning this area off produced less aggression, it would seem possible that chronic psychological stress increased activation in the CA2 area. The role of vasopressin is also important because it is involved in social bonding in certain mammals, including humans. Vasopressin is initiated in the hypothalamus, a key player in regulating the body's baseline (homeostasis) of the way we function, as well as in initiating and ending the stress response (via the HPA axis - sympathetic and parasympathetic nervous system).

Chronic stress plays a key role in many human dysfunctions, it is also known to affect the hippocampus, both altering its size (hippocampal shrinkage) and function. The hippocampus is involved in the way we create, store and recall memories as well as, spatial orientation, location (the maps within the mind) and social behaviour, including aggression/attack behaviours.

The obvious takeaway for us, from this research, is, do all we can to reduce unnecessary (dis)stress and anxiety. To that end, I have spent the last 18 years studying the ways in which stress and anxiety deplete the joy of living and make the world appear more fearful, in most cases, than it is in reality. For sure, there are some places in the world that surviving the day is a challenge, e.g. Syria, Afghanistan and some parts of many inner cities. However, for the most part, the day rolls by fairly uneventfully but for some, who live in a relatively safe environment, their brain reacts as if they lived in a war zone. Life should not be that way and even if we do live in a challenging environment, it is clear that some people are more relaxed, calmer and, less stressed as a result.

So, if you want life to be good, to live in accordance with the reality of your environment, hypnotherapy offers a solution. The stress response is a vital and essential part of responding to real danger and when that is over, the brain systems return to normal; normally! However, when we are chronically stressed, they fail to return to their baseline and we become hyperaroused, more prone to snap for the slightest things. If you want more control over your life, then hypnotherapy provides effective solutions, solutions that make life work better; really!

Hypnotherapy stands out as one of the most effective strategic life management methods there is, especially in its ability to promote clear thinking and good states of mental wellness. The behaviours that make life challenging are often a result of too much stress, too little sleep and too little by way of clarity! So, to take back control of your mind and your life, it makes perfect sense to use a methodology that addresses the subconscious mind's role in perpetuating negative, vague and ambiguous states of mind. Hypnosis helps us to create calm relaxing states of mind that make life work better! If you would like to address any concerns you have in this direction, or, if you just want to make your life feel better,  then why not make an appointment for a Free Consultation? Hypnosis gives you the ability to have a good life! 

The objective here is to help people understand how and why we become illogically trapped into irrational emotional experiences that may actually be happening for reasons different to that which we would imagine! If you want to know more about how Hypnotherapy can help you; why not make an appointment for a Free Consultation?

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The Research: 

Columbia scientists have identified a brain region that helps tell an animal when to attack an intruder and when to accept it into its home. This brain area, called CA2, is part of the hippocampus, a larger brain structure known to be critical for our memory of people, places, things and events.

CA2 was already known to specialize in social memory, the ability to remember encounters with others. Surprisingly, today's findings reveal that a single brain region can control both higher-order cognition, like social memory, and an innate, instinctual behaviour like social aggression. And because CA2 dysfunction has been implicated in psychiatric diseases, such as schizophrenia and bipolar disorder, these results provide further support that altered CA2 function may contribute to abnormal social behaviours associated with such illnesses.

This research was published today in Nature.

"Humans and mice are social creatures. We both engage in learned and innate social interactions that sometimes foster cooperation, and other times drive competition for mates, food and dominance. How the brain mediates these conflicting impulses has been a puzzling question," said Steven A. Siegelbaum, PhD, the Gerald D. Fischbach, MD Professor and Chair of Neuroscience at Columbia University Irving Medical Center, principal investigator at Columbia's Zuckerman Institute and the paper's senior author.

"Today's study in mice shows us that diminutive CA2, which is made up of just a few thousand cells, acts as a nexus of social behaviours, allowing memory to influence the decision to engage in social aggression," he continued.

Although a great deal is known about the other regions of the hippocampus, the small size of CA2, coupled with its inaccessible location sandwiched between larger, neighbouring areas, make it challenging to study. But in 2014, the Siegelbaum lab developed a genetic approach for turning CA2 on or off and discovered that this region is essential for social memory.

As a first step to determine whether CA2 may regulate other social behaviours, the researchers examined the brain regions that receive information from CA2. They found that CA2 sends a strong connection to the lateral septum, a brain region that had been known for some time to play an important role in limiting aggression. Indeed, both classic and more recent studies have shown that brain lesions to the lateral septum in several species, including humans, promote a hyper-aggressive state.

"CA2's close ties to the lateral septum made us wonder whether it also played a role in this type of aggression," said Felix Leroy, PhD, an associate research scientist in the Siegelbaum lab and the paper's first author.

To find out, the researchers temporarily turned off CA2 in a mouse living alone in its home cage. They then introduced an intruder into the cage and observed the resulting behaviour.

When CA2 was switched off, there was a marked decrease in the tendency of the residents to attack, compared to what would normally occur. This difference strongly suggested that CA2 normally acts to drive aggressive behaviour, in addition to regulating social memory.

But why would a brain region that controls memory also be used to regulate aggression? One clue comes from the fact that male mice develop a social hierarchy when housed together; a dominant alpha male sits atop this hierarchy, followed by a succession of increasingly submissive males. When a new mouse is introduced into a colony, there are bouts of fights between the stranger and the other mice until the social hierarchy is re-established.

"It appears that, at the beginning of social interaction -- such as when the resident mouse meets an intruder -- the animal's CA2 forms a social memory, a sort of social ID tag, of the other mouse," Dr Leroy continued. "Further along in the interaction between the two mice, a signal generated in CA2 is sent to the lateral septum, which facilitates aggressive behaviour."

A hormone called vasopressin may also be at work, says the research team. When released in the brain, vasopressin regulates a number of social behaviours, so the team asked whether vasopressin might help determine whether a mouse decides to attack.

"We found that the ability of CA2 cells to efficiently activate the lateral septum is greatly enhanced when vasopressin is released in the lateral septum," said Dr Siegelbaum. "Previous research had revealed a link between vasopressin and aggression, and CA2 appears to lie at the centre of this effect."

As vasopressin levels are altered in people with schizophrenia and autism, the researchers hope to further explore whether and how such disorders are tied to CA2 dysfunction.

In 2016, Dr Siegelbaum and fellow Zuckerman Institute Principal Investigator Joseph Gogos, MD, PhD, found that mice carrying a human mutation linked to schizophrenia have a dysfunctional CA2. This provided striking evidence that social memory deficits, a key feature of schizophrenia, may have their origins in CA2.

"People with schizophrenia exhibit a wide range of behavioural alterations, including impaired social memory and altered levels of aggression," said Dr Siegelbaum. "Might this result from a loss or change in CA2 activity? And could these deficits be alleviated by artificially boosting CA2 activity? That is something that our research, and that of others, hopes to reveal."

Story Source:

Materials provided by The Zuckerman Institute at Columbia UniversityNote: Content may be edited for style and length.

Journal Reference:

  1. Felix Leroy, Jung Park, Arun Asok, David H. Brann, Torcato Meira, Lara M. Boyle, Eric W. Buss, Eric R. Kandel, Steven A. Siegelbaum. A circuit from hippocampal CA2 to lateral septum disinhibits social aggressionNature, 2018; DOI: 10.1038/s41586-018-0772-0

Cite This Page:

The Zuckerman Institute at Columbia University. "Friend or Foe? The brain area that controls social memory also triggers aggression: Mouse study reveals the importance of memory in driving key social behaviour; offers insight into psychiatric disorders such as schizophrenia." ScienceDaily. ScienceDaily, 5 December 2018. <www.sciencedaily.com/releases/2018/12/181205133916.htm>.