Monkeys can feel their heartbeat. This may be good news for psychiatry science

You know when your heart is racing — whether from a tarantula on your lap or a text from a crush. And according to a new study, monkeys do just that, too. For the first time, scientists have found evidence that a non-human animal senses its own heartbeat – a finding that may help scientists study human emotions at the cellular level.

The ability to sense our inner worlds—everything from heart palpitations to a full bladder—is known as intrinsic sense. Just as touch, taste, and smell help us encode sensory information about the outside world, our internal senses alert us to what’s going on inside our bodies. Internal interference “seems to underpin everything” in the human experience, from cognition to consciousness, says Elisa Bliss Morrow, a psychologist and neuroscientist at the California National Primate Research Center, who led the study. “It allows us to navigate the world effectively.”

In recent decades, scientists have linked sensory sensitivity, emotional perception, and a variety of mental health conditions. People who are not good at detecting heart rate, for example, They are more likely than their peers To experience major depressive disorder. By studying the physiology of intrinsic sense, scientists hope to eventually learn more about how various psychological disorders arise and develop.

But internal cognition is difficult to study, mainly because related brain structures such as the cerebral cortex are located in “no-go areas” that are inaccessible without invasive surgery, says W. Kyle Simmons, a cognitive neuroscientist at Oklahoma State University, Tulsa, who He did not participate in the study. So, in an effort to find a similar system, Bliss-Moreau and her colleagues turned to monkeys, because Previous studies He hinted that they might also be able to listen to their own body.

To find out, the team replicated a previous study design of human infants. In that experiment, scientists attached 41 children to an electrocardiogram, which monitored their heart rate, and an infrared eye tracker, which tracked their gaze direction. On a screen in front of them, the children watched videos of bouncing shapes – yellow clouds and pink polygons. Some shapes bounced between the top and bottom of the screen in sync with the children’s heartbeat, while others bounced asynchronously—either too fast or too slow.

Because children tend to pay more attention to stimuli they find surprising or misplaced, they spend more time looking at shapes that bounce asynchronously with their beating hearts, indicating that theyIn line with their tachycardia.

When Bliss-Moreau and her colleagues repeated the study in four rhesus macaques (macaca molata), all monkeys distinguished between synchronous and asynchronous stimuli. The animals spent an average of 1.01 seconds looking at the shapes as they bounced back at the same speed as their pulse, but they took 0.83 and 0.68 extra secondsrespectively, when the shapes moved faster or slower by 10%, researchers report today in Proceedings of the National Academy of Sciences. These results were performed for 100 trials per monkey – and they largely matched the infant rates.

Simmons asserts that this is the first strong evidence of interference in non-human primates. This opens the door to some new approaches that may help us understand [its] biological basis. “

Bliss Moreau says the discovery could also help bridge the gaps between physiology and behavioral psychology. Now that we know that monkeys use the same interoceptive cues as humans, researchers can investigate the relationship between the heart and isolation, for example, in organisms closest to humans, both behaviorally and physically. Most studies of complex psychological functions are now performed in rodents, which have completely different nervous systems and sensory processing mechanisms than humans. Although the ethical concerns of working with nonhuman primates abound, Bliss-Moreau asserts that scientists will learn far more from monkeys than they can from mice and rats.

“We really ask, in the end, how and why emotions such as those felt by us humans emerged,” says Bliss-Moreau. “I bet he will be a model for a monkey [helps us understand] Causal neural mechanisms.” She added that if researchers could trace the circuits responsible for feelings and emotions, perhaps they could begin to predict and prevent various mental health conditions.

However, there are still important differences between the brains of monkeys and humans — particularly in the areas that underlie higher levels of thinking, Simmons says. “It’s not a perfect model. But it brings us closer to that than we were before.”

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