New discovery about monkeys could lead to breakthroughs in treating humans

By Stephen Beech via SWNS

Rhesus monkeys can perceive their own heartbeats - a discovery that could lead to breakthroughs in treating dementia in humans, according to a new study.

Scientists say it provides an "important model" for future psychiatric research into depression, anxiety and Alzheimer's disease.

The ground-breaking study was conducted by researchers at Royal Holloway, University of London, and the California National Primate Research Centre at the University of California, Davis.

The team say they have created a first-of-its-kind animal model of 'interoception' - the ability to sense the internal state of one’s body, such as observing when your heart races or breathing quickens.

The study is part of a collaboration between Doctor Eliza Bliss-Moreau, Associate Professor of Psychology at UC Davis, and Professor Manos Tsakiris, from the Department of Psychology at Royal Holloway.

The team monitored four rhesus monkeys that sat in front of an infrared eye tracker displaying stimuli that bounced and generated a sound either synchronously or asynchronously (faster and slower) with the monkeys’ heartbeats.

They explained that such an experiment capitalises on the fact that monkeys and human babies look for longer at things that they find surprising or are unexpected.

All four monkeys spent more time looking at the stimuli presented out of rhythm with their heartbeats compared to stimuli in rhythm with their heartbeats - suggesting that they sensed that the out of rhythm stimuli was surprising based on the expected rhythm of their heartbeats.

The researchers said that the results are consistent with evidence previously shown in human infants using a similar method, and provide the first behavioural evidence that rhesus monkeys have a human-like capacity to perceive their heartbeats and have an interoceptive sense.

Dr. Bliss-Moreau said: “Interoception, or the self-monitoring of your physiological systems, is involved in all aspects of human life.

"The ability to sense our internal state can indicate issues within the body that require our attention.

"Impaired interoceptive awareness is associated with less capacity to regulate emotions and increased susceptibility to mental health issues such as anxiety and depression."

Prof. Tsakiris said: “Interoception is hugely important for emotion regulation and mental health in adults, and yet we know very little about how it develops in early infancy or comes to be across evolutionary time.

“The work we present here represents a first successful attempt to fill these gaps.”

The researchers said that deficits in interoception have also been linked to neurodegenerative diseases such as Alzheimer’s.

Dr. Bliss-Moreau said: “This model will be used in future translational studies of neurodegenerative diseases, including Alzheimer’s.

“If we can measure interoception, we can track it as a behavioural biomarker of disease progression.”

She said the study provides insights into how the rhesus macaque model may be used to further our understanding of brain and body function.

Prof Tsakiris added: “A next step is to study the mechanism by which interoception may be involved in different psychiatric and neuropsychiatric conditions."

The findings were published in the journal Proceedings of the National Academy of Sciences.