In a new study, researchers found a new similarity between monkeys, particularly rhesus macaques, and humans: the ability to sense the internal state of their body by perceiving their heartbeats.

This suggests the study can lead to new animal models to understand mental disorders like anxiety and depression better, an Independent report specified.

Furthermore, the study leads to the development of a "first-of-its-kind" animal model of interoception, the ability to sense the body's internal state like perceiving one's breathing or blushing cheeks.

According to Elizabeth Bliss-Moreau, the study co-author from the University of California Davis, interception, or the self-monitoring of physiological systems, is involved in all human life aspects.

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Monkeys and humans
(Photo: JEAN-PHILIPPE KSIAZEK/AFP via Getty Images)
Researchers have found a new similarity between humans and monkeys: their ability to perceive their heartbeats.

The Ability to Control Emotions

The ability to sense the body's internal state can indicate issues that need attention, and a damaged interoception is associated with less capacity to control emotions and increased vulnerability to mental illnesses such as anxiety.

The study investigators said the findings could result in new ways of examining psychiatric and neuropsychiatry dysfunctions like depression, anxiety, and Alzheimer's disease.

In the research published in the PNAS journal, scientists monitored four rhesus monkeys sitting in front of an infrared eye tracker exhibiting stimuli that bounced and produced a sound either synchronously or asynchronously, or faster or slower, with the heartbeats of the monkeys. The experiment worked because both human babies and monkeys are looking for longer at things they find unexpected or surprising.

Synchronized with Heartbeats

Researchers discovered that all four monkeys spent a long time searching for the stimuli presented out of rhythm with their heartbeats compared to stimuli synchronized with their heartbeats.

This proposes that the monkeys sensed the out-of-rhythm stimuli to be shocking based on their heartbeats' expected rhythm. The outcome was consistent with past evidence shown in human babies.

The degree to which the four monkeys paid more attention to "out-of-sync" stimuli than the in-sync ones was quite close to the difference in human infants, researchers reported in The Conversation. The study authors reported that these study findings strongly recommend that monkeys have a natural sense of their heartbeats.


Monkeys Have Interoceptive Sense Akin to Humans

In a New Scientist report through MSN, study authors said rhesus monkeys have a human-like interoceptive sense, which has been discovered to be key to human emotional encounters, having a sense of self, and even consciousness.

Manos Tsakiris, another co-author of the research, said, interception is highly essential for emotion control and mental health among adults, and yet it's known very little about how it develops in early infancy or comes to be across evolutionary time.

In future studies, researchers hope to understand if some monkeys are better than others when it comes to sensing their heartbeat and if variation among the primates in this ability translates to other psychological features.

Since monkeys have shorter lifespans than humans, the study investigators are hoping to study further, using the animal model, how the interoception is developing, what environmental features are shaping it, and what neural systems are underlying it, tracking the animals from "from womb to tomb." Dr. Bliss-Moreau explained that if interoception can be measured, it can be tracked as a behavioral biomarker of disease progression.

Related information about the what humans and monkeys have in common is shown on OPB's YouTube video below:

 

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