People naturally tie emotional experiences to their bodily feelings. For instance, “my heart was pounding” or “my stomach was in knots.” But little is known about how these internal signals might impact the ways in which our memory works.

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The connections between heart and brain run deep.

As early as 1894, W. James, an American philosopher, physician and psychologist, asked whether the subliminal perception of visceral body signals might be involved in emotional experiences.

Only recently has interest returned to exploring changes in our internal state and their connection to mental experiences.

The unmistakably warm emotion we feel when presented with a person or place we know well is an experience everyone is familiar with.

A new study, published in the Journal of Experimental Psychology: General, investigates cardiac signals and their impact on the sensations of familiarity.

The study sets out to discover whether the internal feeling of a heartbeat has the subliminal power to alter the way we perceive our own memories.

Lead author Chris Fiacconi, a post-doc at Western University’s Brain and Mind Institute, Canada, thinks that subtle signals from within our organs might influence our experiences. He believes his research shows that “bodily sensations may […] accompany the activation of memories in experiences that we traditionally describe as feelings.”

To investigate this pairing, the team presented participants with images of faces at different stages of their cardiac cycle. Some faces were presented during the systolic phase as the heart contracts and others during the diastolic phase when the heart is relaxed.

As blood is ejected from the heart into the aorta during systole, pressure receptors in the aorta (a large blood vessel that leaves the heart) register an increase in pressure and feed this back to the brainstem, where the information is used to monitor and control blood pressure. These signals are also fired into higher brain regions, informing it about the general state of our physiology at any given moment.

During the experiment, the study group was asked to rate the faces they were presented with as familiar or unfamiliar. The results showed that people were significantly more likely to rate faces as familiar if they were presented to them while the heart was undergoing a systolic contraction.

In other words, when the heart was working, and aortic pressure was at its height, feelings of familiarity were increased.

Stefan Köhler, principal investigator and psychology professor at Western University’s Brain and Mind Institute, says:

These new findings suggest that signals from the body not only shape our emotional feelings, but also affect more broadly our memory experience, such as feelings of familiarity, and perhaps other aspects of memory that are linked to intuition.”

The results seem counterintuitive to someone unfamiliar with this field of investigation. Medical News Today asked Fiacconi whether he was surprised by the findings.

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Feelings of familiarity are intimately tied to our hearts.

He said: “Although the rationale for our study, as well as our predictions, were well supported by prior research, we were indeed surprised with how clear and orderly our results were.”

He also stressed that connections between the brain and heart are well-documented, so some level of communication is to be expected.

MNT asked Fiacconi if he had any theories as to why such a mechanism might have evolved in humans. He posited that when humans were living in the wild, knowing whether a specific person, creature or object was safe to approach was vital for survival.

He believes feelings of familiarity can be considered an “approach signal.”

He theorizes that the cardiac-brain neural linkages might be used in these emotions of “familiarity.” When the researchers presented images at specific points in the cardiac cycle, they “tricked” the brain into the “familiarity” state of mind.

MNT asked whether the team plans to carry out more work along similar lines, Fiacconi said that they are already running follow-up experiments and have more planned. One question they hope to answer in the future is “how the brain regions that receive input from the cardiovascular system interface with other regions known to play an important role in memory.”

To this end, he would like the chance to use measures of cardiac function, such as ECG (electrocardiogram), alongside MRI (functional magnetic imaging) brain scanning technology. This could uncover deeper connections between the two organs and the timings of any communication.

Another question the researchers plan to investigate is “how feedback to the brain from the cardiovascular system may be altered in cardiovascular disease, and whether memory deficits commonly seen in neurological disease are related to problems integrating bodily information with stored memory traces.”

As mentioned in the introduction, this field of research has been discussed historically, but it is only now that solid data is being harvested. It seems that our gut feelings are not only confined to our guts.

MNT recently covered research showing that people who follow their instincts might be more trustworthy.