The Investigation report is a short take on an interesting academic paper.
the big idea
Rhesus monkeys have a sense of when their own hearts are beatingaccording to new research we conducted.
Sensing one’s own physiological states, such as heartbeat, breathing, or flushed cheeks, is called interception. Some previous research has shown that animals can be trained to perform tasks that demonstrate this ability. Decades ago, a team of scientists showed that rhesus monkeys could be trained to raise and lower your heart rate. But one open question has been whether monkeys have an unlearned ability to sense their bodily signals rather than being taught to do so.
Both human babies and monkeys look at things that are unexpected or novel longer than they look at things they expect or are used to seeing. We use a task based on this behavior, originally developed for test whether human babies can feel their own heartbeat – to find out if monkeys also have this ability.
We first had our monkeys sit in chairs in front of a computer screen and hooked them up to EKGs to monitor their heartbeats. We then play videos of a yellow or green cloud bouncing up and down accompanied by beeps. Sometimes we timed the bounces and beeps to match the monkey’s heartbeat, and other times they were out of sync.
We then used eye trackers to measure how long the monkeys looked at the images. If the monkeys had a sense of their own heartbeat, they would find the synchronized bounce less interesting and novel than the unsynchronized bounce, and would therefore spend more time looking at the unsynchronized image.
We tried four monkeys and, just like human babiesthey looked at the forms that bounced and sounded out of sync with their heartbeats for much longer – almost three-quarters of a second – than the synchronized images. Furthermore, the extent to which our monkeys paid more attention to unsynchronized shapes than to synchronized shapes was very close to the difference in human babies. These findings strongly suggest that monkeys have an innate sense of their own heartbeat.
Kathy West/CNPRC, CC BY-ND
why does it matter
Heartbeat screening tests are most commonly used to assess how aware people are of bodily signals.
In humans, this ability is believed to be essential for emotional experienceshaving a sense of self, memory, knowledge of one’s own cognition and even awareness. Abnormally low or high interoception is related to disorders such as anxiety Y depression.
Our work establishes that monkeys and people have a similar sense of heartbeat and establishes a method for testing this ability across species.
Whats Next
People are very aware of many subtle physiological functions, not just the beating of their own heart. But while some people have very keen interoceptive ability, many humans are really bad in tasks such as studying. Next, our team plans to test whether, like people, some monkeys are better than others at detecting their own heartbeats, and whether this translates into other psychological characteristics.
Finally, with monkeys, researchers can track animals from the womb to the grave, have exquisite experimental control, and can carry out detailed anatomical evaluations. This access may allow researchers to determine how interoceptive ability develops, what features of the social and physical environment shape it, and what neural systems underlie it.
Establishing this knowledge could promote investigation of the causes behind many health challenges caused when interoception goes wrong, including mental health disorders, neurodegenerative disorders Y aging.
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