Many phrases and metaphors relate to the heart and the brain: “Follow your heart.” “Mind over matter.” “He has a cold heart.” “She has a steel mind.”
This sometimes makes it seem that the heart and the brain are separate, each living in its own world, without connection to the other. Research shows, however, that the heart and the brain are interconnected, with one organ passing information along to the other. Importantly, we can recognize — and manipulate — our heart and brain through our heartbeats.
At the University of Sussex, Dr. Sarah Garfinkel tells the story of how emotions and cognition are embodied: how your heartbeats and awareness can shape your emotional state, ranging from anxiety levels to decision-making. These internal signals report back on the homeostatic state of the body, alerting the person to states like hunger and thirst, anxiety, and pain. This awareness is called “interoception”: the sensing of physiological signals, including heart rate. Most of us know this ability as your “gut feeling.”
One way the body and brain communicate is via baroreceptors, which are sensitive to pressure and stretch in the heart and arteries. Every time the heart ejects blood, the baroreceptors analyze the strength and timing of each heartbeat, and send the information to the brain via the vagus and glossopharyngeal nerves. This is the major mechanism for fast- and short-term blood pressure regulation. It is also the primary way the body communicates the ever-changing state of the heart to the brain.
Every time the heart beats, the brain flashes, and the brain’s flashes coincide with how fast and how hard the heart is beating. The brain changes alongside the heart’s dynamic state, that is, the amygdala and thalamus — regions associated with fear and pain — affected by this heart-brain relationship. Your brain, therefore, is its own entity, but it also represents the body’s activity, including that of other organs. How your organs react to stimuli can dictate how your brain responds.
The brain and body shouldn’t be separated; instead, the brain should be seen as being enmeshed with the body. This is important in offering ways of treating anxiety or behavioral and emotional issues. Making people more aware of their bodily sensations can make them more aware of emotions, and more empathetic toward others.
This is why engaging in meditation or yoga, which increases awareness of bodily sensations, can help develop emotional intelligence. When practicing yoga poses regularly, people become more attuned to how their body feels in the poses. This makes them aware not only of their body in space, but also of the state of their body, that is, interoception. Being more “interoceptive” — more aware of the body — also gives people a chance to change their internal state.
Heartbeats are frequent, distinct, and can be easily counted within a time frame, or associated with changes in external stimuli. In other words, heartbeats can be noted in a variety of situations and provide easily obtained quantitative data. Therefore by measuring a person’s awareness of their heartbeats, one can measure interoceptive awareness.
Those affected by autism spectrum conditions (ASC) have trouble recognizing and regulating emotions. In a study published in Biological Psychology, Garfinkel’s team decided to study those with autism, since they also to tend to have accompanying anxiety. They found that those with ASC have trouble with interoception. They are less accurate and more sensitive in processing bodily signals; they’re less aware of their own heartbeats. This can be related to the higher rates of anxiety that those with autism tend to suffer from, and the reduced ability they have in being able to recognize their emotions and the emotions of others.
But the inability to recognize interoceptive activity is not relegated only to those with autism or anxiety. When changes in the heart’s state pass a threshold, it becomes a cue to the brain and the person. However, when there are bodily sensations that aren’t accounted for by the person, or easily understood by them to be related to certain stimuli, it can come out as anxiety.
When interoception relates to heart rate, two instances are noted: “systole” and “diastole.” Cardiac systole is when blood is pushed out of the heart as it contracts, and cardiac diastole is when the heart refills with blood as it relaxes. In a study published in The Journal of Neuroscience, Garfinkel and her colleagues examined how faces are processed emotionally. They found that fearful faces were detected more easily and felt more intensely at systole than at diastole. This corresponded with greater amygdala responses to fearful stimuli presented at systole rather than diastole. At the neural level, baroreceptor effects are associated in the processing of threatening stimuli and are involved in the engagement of brain systems related to emotional processing, such as the amygdala.
This is especially important when someone has to make a threat assessment in a fraction of a second. In a study published in Nature Communications, the University of London’s Dr. Ruben Azevedo and his colleagues found that negative racial stereotypes of black people are exaggerated at systole. His study participants were more likely to say that a black man was holding a gun rather than the phone or wallet he was actually holding.
As troubling as this might be, there’s hope, though. These studies lend credence to the idea of interoception being a viable way of increasing empathy. If someone is in a stressful situation, but can recognize their internal state and how it is contributing to their feelings they may be better able to control their reactions to stimuli.
Heartbeat-awareness training is possible. Interoception may be taught, increasing people’s accuracy in awareness of their bodily sensations. This can help people become more aware of their internal state in response to stimuli, for example, a black man holding a cellphone. If a person sees a black person and feels a threat response, being interoceptive may give them the moment they need to collect their thoughts and respond less negatively.
Interoception can also reduce anxiety by decreasing the amount of unrecognized bodily sensations. Staying “cool as a cucumber” can keep your brain from setting itself metaphorically on fire — and keep you connected with yourself and others.
This article was originally published in Brain World Magazine’s Summer 2018 issue.