Autism spectrum disorder study sees monkeys as possible role models

Summary: The study builds on growing evidence that suggests rhesus monkeys could be a good model for studying the social deficits associated with autism spectrum disorders.

Source: Florida Institute of Technology

New research builds on growing evidence demonstrating the importance of rhesus macaque monkeys (Macaca mulatta) as a model for key social impairments seen in autism spectrum disorders (ASD).

ASD is an early neurodevelopmental condition characterized by persistent impairments in social communication and interaction. Despite its prevalence and societal cost, its basic disease mechanisms remain poorly understood in part due to over-reliance on rodent models, which lack the complex social and cognitive skills essential for modeling behavioral symptoms. relevant to human ASDs.

Like humans, rhesus monkeys have complex cognitive abilities and exhibit stable and pronounced individual differences in social functioning, making them a promising model for better understanding the biological and behavioral mechanisms underlying social impairments.

“The sociality of rhesus monkeys is stable over time and related to variation in initiation but not reception of prosocial behavior,” a study led by Assistant Professor Catherine F. Talbot, Ph.D., at Florida Tech School of Psychology and Stanford researchers. The University and University of California, Davis’s California National Primate Research Center, found that several aspects of social functioning differed between monkeys classified as low social and monkeys classified as highly social.

Analyzing three years of data from 95 male rhesus monkeys housed at the California National Primate Research Center in large outdoor social groups in semi-naturalistic habitats, the team first classified the monkeys based on their social behavior natural.

For example, they looked at whether the monkeys engaged in activities such as grooming, which is a behavior that facilitates social bonding in non-human primates, or whether they were near or in contact with other individuals, or if they were just hanging out by themselves with no one else around.

Monkeys that spent the most time alone were classified as unsocial, while monkeys that spent the least time alone were classified as very social. Next, the researchers assessed the differences between the social communication profiles of these two groups of monkeys.

The team found that highly social monkeys initiate more prosocial behavior, which encompasses behaviors like sitting in contact with others and grooming, compared to low social monkeys. However, there was no difference between the frequency with which low-social monkeys and high-social monkeys received prosocial behavior.

“It suggests there’s this underlying social motivator, that we see higher social motivation as very social monkeys, which doesn’t sound like rocket science, but it does support the hypothesis. social motivation of ASDs and provides insight into how this might be affected by the underlying biology,” Talbot said.

“There are several theories or ideas about the causes of the social impairments seen in autism and one of them is that people with ASD have lower social motivation.”

This hypothesis suggests that people with ASD tend to have deficits in social reward processing, leading to decreased social initiation and difficulty fostering and maintaining social bonds. In other words, social interactions are not inherently rewarding.

The team also found that there was no difference in threat behavior between low-social and high-social monkeys, either in initiating or receiving threats. This was contrary to their hypothesis, where they believed that if unsocial monkeys did not communicate effectively with their peers, they would be more likely to be bullied and sustain traumatic injuries, which they found in previous research.

This shows rhesus monkeys
Like humans, rhesus monkeys have complex cognitive abilities and exhibit stable and pronounced individual differences in social functioning, making them a promising model for better understanding the biological and behavioral mechanisms underlying social impairments. Credit: Kathy West

Findings from the current study better characterize this natural, unsocial phenotype and may help researchers gain mechanistic insight into the social motivation deficits seen in people with ASD.

“There really hasn’t been a lot of work done on rhesus macaques as a model for ASD,” Talbot said.

“What we are modeling are natural social deficits. So in humans, autism spectrum disorder is just that – a spectrum – and you see these traits that are distributed throughout the human population, not just the clinical population. People who cannot be classified as part of the spectrum will also exhibit some of these traits. »

People with ASD may also experience deficits in other social-cognitive skills like theory of mind, which involves understanding that one’s own personal beliefs and knowledge are different from those of others.

Gaze tracking and understanding what another person is looking at is another component of theory of mind. Impaired eye tracking is often one of the first behavioral signs to appear in children with ASD.

The team is also working on research looking at the underlying biology of low social and high social monkeys and how this might relate to their performance on other social cognitive tasks, including how monkeys track the gaze of their peers, how well they interact with their peers, how well they identify faces, and how this compares to their performance in the non-social domain, such as how well they identify objects.

About this autism research news

Author: Press office
Source: Florida Institute of Technology
Contact: Press Office – Florida Institute of Technology
Picture: Image is credited to Kathy West

Original research: Access closed.
“Rhesus monkey sociality is stable over time and related to variation in initiation but not receipt of prosocial behavior” by Catherine F. Talbot et al. American Journal of Primatology


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Rhesus monkey sociality is stable over time and related to variation in initiation but not reception of prosocial behavior

Rhesus monkeys and humans are highly social primates, but both species exhibit pronounced variation in social functioning, spanning a spectrum of sociality.

Natural low sociality in rhesus monkeys may be a promising construct for modeling social impairments relevant to human autism spectrum disorder (ASD), particularly if low sociality is found to be stable over time and associated with decreased social motivation.

Thus, to better characterize the variation of sociality and social communication profiles, we carried out quantitative assessments of social behaviors on NOT= 95 male rhesus macaques (mulatto macaque) housed in large outdoor groups.

In Study 1, we determined the social classification of our subjects by ranking their total frequency of unsocial behavior. Monkeys with the highest frequency of unsocial behavior were classified as unsocial (not= 20) and the monkeys with the lowest frequency of unsocial behavior were classified as very social (not= 21).

To assess group differences in social communication profiles, in Study 2 we quantified the rates of transient social communication cues and whether these social cues were initiated by or directed to the central subject.

Finally, in Study 3, we assessed the intra-individual stability of sociality in a subset of monkeys (not= 11 low-social, not= 11 high-social) two years after our first observations.

The frequency of non-social behaviors was significantly correlated at both time points (studies 1 and 3). Similarly, lower social classification versus high social classification accurately predicts classification two years later.

Low social level monkeys initiated less prosocial behavior than high social level monkeys, but the groups did not differ in reception of prosocial behavior, nor in threatening behavior.

These results indicate that sociality is a stable, trait-like characteristic, and that low sociality is related to decreased initiation of prosocial behavior in rhesus macaques.

This evidence also suggests that low sociality may be a useful construct for gaining mechanistic insight into the social motivation deficits often seen in people with ASD.

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