The effects of social isolation on the human neural circuits during the | Cell Press Paper Express

Life science social balance is a personal ability to detect the quantity and quality of social connections, compare them with the established set points in the command center, and adjust them to seek the best social connections through the effect system The effort spent.

When the social connection is lacking or too much, it will become a positive or negative stimulus, respectively.

Insufficient social interaction for a long time will cause adjustments to the set point, making it an excess experience to re-enter the best state before.

On March 9, 2021, a research team from the University of California, the Weizmann Institute of Science, and the Sack Institute of Biological Research published a new study titled "The neural circuitry of "social homeostasis: Consequences of acute versus chronic social isolation", the researchers used the previous social balance model as a basis and included adaptation to continuous changes in environmental conditions, such as long-term isolation.

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How should we adapt to the long-term changes in opportunities for social participation? Social balance is an adaptive function that adjusts the behavior that governs social contact to an optimal level and avoids excessive social contact (that is, competition for resources, space, and spouse becomes too fierce) or insufficient social contact (lack of safety) , Warmth, observational learning and play) (Matthews and Tye, 2019).The lack of human perception of the objective quantity or subjective quality of social contact (ie "loneliness" (Weiss, 1973)) is related to mental (Cacioppo et al, 2006a) and physical health impairment (Hawkley and Cacioppo, 2010; Hawkley et al.
, 2006), and higher mortality rates (Berkman and Syme, 1979; Holt-Lunstad et al.
, 2010; Holwerda et al.
, 2012; Perissinotto et al.
, 2012; Steptoe et al.
, 2013).

Perceived loneliness is associated with increased morbidity and mortality of cancer and cardiovascular diseases (Hawkley and Cacioppo, 2003), as well as with its response to viral immune challenges (LeRoy et al.
, 2017) and inflammatory responses (Balter et al.
, 2019) is related to the severity of symptoms.

Many studies have proved that individual differences in social participation patterns between different species and within the same species are predetermined by genetic factors (Forkosh et al.
, 2019; Hoekstra and Coyne, 2007; Lim et al.
, 2004; Wang et al.
al.
, 2008), there is a neural circuit mechanism when a specific individual adapts to and responds to the ever-changing social environment, but we know very little about it.

 An unprecedented global pandemic occurred in 2020, which triggered mandatory government blockades in many cities and countries/regions, as well as long-term "social isolation".
The urgent need for isolation has greatly changed the social outlook of almost everyone on the planet.
.

We are faced with severe needs to slow the spread of COVID-19 and maintain social needs, but there is a conflict between the two.

In fact, how to assess the uncertainty of these two competing needs has always been a challenge.
It has caused huge controversy and has been severely politicized, and the assessment of this uncertainty has shown a wide range of individualization.Here, we propose a conceptual framework to understand the dynamic response and adaptive behavior of individuals in the face of changes in the personal social environment.

This conceptual framework provides a mechanism for explaining how the price of social stimulus (regardless of whether it is evaluated as positive or negative) changes from short-term isolation to long-term isolation, for the same stimulus (re-entering a social group).

We propose that the emotional price of social stimuli (Tye, 2018) can be regulated by the individual's internal demand state.

Excessive social interaction will change the individual’s perceived price of social contact, and the reduction in the social balance set point caused by isolation may make the social stimulus that was once considered the best now an excess.

This may explain why prolonged social isolation produces antisocial behavior, while short-term social isolation produces prosocial behavior.

The neural composition of social balance Social balance is a personal ability to detect the quantity and quality of social contact, compare it with the established set point of the command center, and adjust the energy spent seeking social contact through the effect system (Figure 1 and Table 1) (Matthews and Tye, 2019).

Therefore, the neural components of social balance include: 1) Detector; 2) Control Center; 3) Effector.

1.
Detection system The first step in the social balance system is to detect the social environment.

The detection system node is responsible for sensing deviations in the quality and quantity of social contacts (Matthews and Tye, 2019).

The number of social interactions can be judged by objective measurement standards, but its quality is subjective and highly dependent on the environment, including relative advantages, social hierarchy, identity characteristics, relationship history and other factors (Shemesh et al.
, 2013 ; 2016).

We hypothesize that, especially in non-acquaintance relationships, the characteristic information of social stimuli (such as gender, age, etc.
) has a higher weight in the evaluation of social interactions, and plays a heuristic role (Figure 1A). As familiarity increases, the known identity of an individual has greater weight in determining the quality of a particular interaction (Figure 1B).

We conceptualized the detected overall social interaction and operationally defined it as social utility—the product of the quantity and quality of social contact, where personal preference is when the number of personally preferred social connections monotonically rises to the optimal point The quality of social interaction monotonously increases to the optimal point.
When there is an excess of social interaction, the quality decreases (Figure 2).

In other words, if the quality of social interaction is very low, then even with the best or very high quantity, the social utility is still very low.

In addition, if the quality of social interaction is high, but the quantity is small, the social utility is still low.

If the quantity is very high, even if the quality is high, it is a surplus and the corresponding social utility is low.

However, if the quality is high and the quantity is optimal, this provides the greatest social utility.

2.
Command Center The command center (or control center) has the function of calculating the "deficit" or "surplus" of social interaction.

The necessary functions of any balance control center include: 1) receiving input values ​​from the detection system; 2) storing information about the balance set point; 3) calculating the difference between the input value and storing the set point; 4) changing Any deviation from the set point is sent to the downstream effect system (Cannon, 1929).

The Social Balance Control Center combines the information about the status quo of social participation with the individual's desired quality/quantity of social contact (balance set point) to calculate whether social contact is in a state of insufficient or surplus.

If a "deficit" or "surplus" is detected, this deviation from the expected set point will trigger the participation of the "effect" system to correct the aforementioned changes.

3.
Effect system The effect system in the balance system is mainly responsible for driving motivational behaviors, and also has a physiological adaptation function for maintaining social balance (Cannon, 1929).

The requirements for the effect system include: 1) must accept input from the control center; 2) the activation of the effect system must be able to drive behavior or physiological adaptation, and does not depend on the individual's balanced demand state.

In recent years, the emergence of neural recording and manipulation technology has prompted people to have an unprecedented understanding of the basic circuits of social behavior, such as the two-way regulation of social behavior by BLA-mPFC and BLA-vCA1 (Felix-Ortiz and Tye, 2014; Felix-Ortiz) et al.
, 2016), the influence of neuromodulation on social rewards and social behavior (Dölen et al.
, 2013; Gunaydin et al.
, 2014), and the neural circuits of aggressive or aggressive behavior (Hong et al.
, 2014; Lin et al.
, 2011; Lischinsky and Lin, 2020).

When individuals experience short-term or long-term social isolation, the effect system will play a role, and then make the individual show pro-social or anti-social behavior.

 The temporal dynamics of social balance (short-term and long-term isolation) leaving a safe social group (isolation) requires individuals to change their strategies to promote survival.

Although these strategic changes may be adaptive changes in the short term, they may be harmful to isolated individuals.
Short-term (acute) social isolation often produces unintended consequences of maladaptation.

The consequences of short-term isolation include the impact on physical health and the central nervous system, which may cause the individual to enter a state of high vigilance/vigilance or stress, and stimulate a corresponding immune response.

These changes may trigger individual defensive behaviors and protect isolated individuals from environmental threats.

The individual’s perceived loneliness and objective social isolation will produce a state of hyper-alertness and high excitement, which may be an evolutionary feature to detect and protect oneself from environmental threats that may come from isolation (Cacioppo et al.
, 2006b) .

Chronic or prolonged social isolation (this is a relative time scale, which may vary with species, environment, individuals and past experiences) will lead to many changes in individual biology and behavior, which can be said to be adaptation Sexual, can also be said to be non-adaptive, including physical, psychological and behavioral consequences.

We explored the basis of the transition from short-term social isolation to long-term social isolation, and proposed the hypothesis that this transition occurred due to (1) time or (2) the correction of the social balance effect system (Figure 2A).

Perhaps there is a timing component in the neural circuit, which is similar to duration, used to determine that a brief environmental change is actually long enough to trigger neural adaptation.

In addition, the transition from acute isolated behavior to chronic behavior is not determined by external signals, but triggered by the nervous system's threshold for correcting excess or insufficient social contact.

Future experiments need to explore these possibilities in depth.

Outlook In the context of a global pandemic, unpredictable lockdowns and a variety of different quarantine guidelines have emerged around the world.
In recent history, there is no period in recent history that needs to examine the neural mechanisms of social balance more urgently than now.

While working hard to contain the new crown epidemic, there is an urgent need for further research on the unexpected health consequences of social isolation.

At present, thanks to existing frameworks from other homeostatic systems and recent findings in socially isolated animals, we have the opportunity to conceptualize the neural circuits and mechanisms of social balance (Figure 3), although in terms of fully understanding this system There is still much work to be done.

Considering that pandemics and other socially disruptive events are likely to happen again, proactively studying the costs of social isolation can mitigate uncertain future effects.

Table 1: Glossary of terms in the context of social behavior.
Definition of terms.
The interests and resources of autocracy.
The interests and resources of egalitarianism.
The interests and resources of egalitarianism are favored by those with high authority.
The social structure of different individuals is more evenly distributed.
Social balance.
And quality, and maintain a stable ability in the social structure.
The detection system perceives the changes in the number of individual social interactions and the quality of the social environment.
It integrates the characteristics of the social subject, relative power level, identity and other factors.
The number of social contacts detected by the social utility The product of mass. When the number of personally preferred social interactions increases to the optimal point, the quality of personally preferred social interactions increases monotonously.
When there is an excess of social contacts, the quality decreases.
The balance sets the point.
Personal ideal social utility level.
Command center A nervous system , Which can compare the deviation of social utility with the balance set point of the code to calculate the insufficient or excessive pro-social (affinity) behavior in social interaction to promote group cohesion social behavior (friendly/positive posture), such as dressing, dressing, Touching, hugging and other anti-social behaviors that damage group cohesion, such as aggression, intimidation, fighting effect system, a nervous system that coordinates and stimulates behavior to solve the problem of insufficient and excess social utility (such as pro-social affinity behavior or anti-social behavior) Aggressive behavior) loneliness.
When a person feels the gap between their desire for social connection and actual experience, the pain or discomfort that occurs.
The price is positive or negative.
Short-term and long-term (acute and chronic) In this review, short-term and long-term (acute and chronic) social isolation refer to relative time scales, because the life span, reproductive cycle, metabolism, etc.
of different species are different, the threshold of short-term and long-term social isolation may also be The original texts of different related papers are published in the Cell journal of CellPress,