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The brain has long been seen as the only place where thinking happens. But a broad review of research from body science, neuroscience, transplant surgery, public health and environmental engineering argues that the brain does not work alone. Organs inside the body, including the heart, lungs, stomach, intestines, liver, kidneys and even the bladder, can affect memory, voluntary actions, awareness and how we understand other people. These abilities are often seen as key parts of the human mind. Sensors throughout the body constantly track things such as heart rate, how deeply we breathe and how the stomach contracts. They send this information through the vagus nerve and pathways in the spinal cord to the brainstem, thalamus and outer layers of the brain. For decades, brain researchers treated much of this information as background noise that the brain needed to ignore. But the authors say important studies from the past ten years have changed this view. They show that interoception—the ability to sense what is happening inside the body—does much more than keep basic body functions running. It can also affect complex thinking.
The researchers draw on many kinds of evidence. At the body level, electrocardiography measures heart activity, electrogastrography records stomach contractions, swallowable pills track acidity, temperature and pressure inside the digestive system, and wearable sensors measure breathing rate and gases in exhaled air. In the brain, electroencephalography and magnetoencephalography detect patterns of electrical and magnetic activity, including brain responses linked to heartbeats and breathing. Functional magnetic resonance imaging shows brain networks that follow stomach and breathing rhythms. Tests and questionnaires also measure how people sense their bodies. The review divides interoception into three parts: interoceptive accuracy, or how well someone can detect signals such as heartbeats or breaths; interoceptive sensibility, or how much attention someone says they pay to these signals; and interoceptive awareness, or how closely a person's reported feelings match their measured ability. The authors group the ways internal organs affect thinking into three pathways. In the first, activity in an organ directly changes how the brain processes information. In the second, one organ affects another organ, which then influences thinking. In the third, activity inside the body changes the brain's or body's overall state.
The heart appears to have a strong influence on memory. Signals from pressure sensors that occur during systole, the part of the heartbeat when the heart contracts, seem to activate noradrenergic pathways involved in memory. People who were less accurate at sensing their internal signals had more trouble remembering words shown during systole than words shown during diastole, when the heart relaxes. People who counted their heartbeats more accurately were less affected by this problem. Greater accuracy in sensing heartbeats, feedback timed to systole and increased activity in the cardiovascular system were also linked to better learning of frightening images or events. Fearful memories formed during systole led to stronger skin conductance responses, which measure changes in the skin linked to the body's response to emotion. In a virtual threat study, heart rate and skin conductance during the threat were related to how strongly people later remembered feeling aroused. This suggests that emotional memories can preserve patterns of physical arousal present when the memory was formed. Logical memory and verbal learning, which depend on the hippocampus, also improved with better heartbeat-sensing accuracy. This points to brain systems that may be shared by interoception and memory.
Heart signals are also linked to awareness and the sense of self. Brain responses to heartbeats, measured before people viewed a faint pattern of lines, helped predict whether they consciously saw it. People found visual signals harder to detect when they appeared in time with their heartbeats, and the signals produced weaker activity in the insular cortex, a brain area involved in sensing the body's internal state. This effect, called cardio-visual suppression, disappears after damage to the anterior insula. In people with disorders of consciousness, changes in the timing of the heartbeat, heart-rate variability and brain responses to heartbeats can help distinguish a minimally conscious state from a vegetative state, even when patients show no clear outward signs of awareness. Brain activity linked to heartbeats is also related to thoughts about oneself. Spontaneous self-focused thoughts were associated with heartbeat-related brain responses in the ventral precuneus and ventromedial prefrontal cortex. Recordings made directly inside the brain linked thoughts about oneself as a subject to responses in the right anterior insula. When virtual bodies or rubber hands flash in time with a person's heartbeat, the person is more likely to feel that they belong to them. This effect is stronger in people who are better at sensing their heartbeats.
The heart also appears to influence voluntary actions and decisions. People who count their heartbeats more accurately show stronger intentional binding, which is the feeling that the time between an action and its result is shorter than it really is. This effect becomes stronger during systole. Better interoception is linked to less impulsive decision-making without careful planning, less risky behavior involving the body and better control over automatic responses. However, it is also linked to a lower willingness to start voluntary movements during systole. People with poorer interoception tend to show more impulsive behavior. Studies of people with Tourette's syndrome have also found signs of less accurate heartbeat sensing alongside stronger and less predictable bodily sensations linked to their urges before tics. Heart signals may even affect financial decisions. In a study of financial traders who made many trades each day, those who counted their heartbeats more accurately earned more money and were more likely to remain active in the market. People who had attempted suicide performed worse on a heartbeat-tapping task and showed less activity in the insula when focusing on heart sensations. The authors link this pattern to reduced awareness of internal signals and extreme risk-taking.
Social thinking also appears to change with the heartbeat. During systole, when signals from the heart and the perception of threats are strongest, White participants in one study were more likely to mistake tools for weapons after seeing Black faces. They were also more likely to shoot unarmed Black targets in a simulation. These effects were not found during diastole. Faces shown in time with systole were judged to be less trustworthy. People with better interoception also showed a stronger tendency to assume that other people felt the same emotions they themselves were feeling. In an ultimatum game, listening to their own heartbeat made people feel that offers were more unfair and made them more likely to make unfair offers themselves. Feelings of social pain were weaker during systole. The link also works in the other direction. Expecting to speak seems to improve people's ability to sense their bodies, while being left out socially makes them less accurate at sensing their heartbeats. The researchers suggest that this may be a way to draw attention away from painful thoughts about oneself.
The review finds that breathing also plays an important role in mental activity. Air moving through the nose helps coordinate activity in the amygdala, hippocampus and piriform cortex, which are brain areas involved in emotion, memory and smell. Activity in these areas tends to peak around inhalation. People also seem to remember information better when they learn or recall it during inhalation rather than exhalation. The stage of breathing can affect conscious perception too. Breathing changes patterns of brain activity in the posterior alpha frequency band and affects the chance that people notice faint visual targets. In immersive virtual reality, silhouettes that flashed in time with a person's breathing created an illusion that the silhouettes were part of the person's own body. This effect was disrupted when researchers caused participants to experience dyspnoea, or difficult breathing, but not when breaths were delivered mechanically. In an illusion called 'embreathment,' people felt more connected to virtual characters that breathed in time with them than to characters that breathed out of sync. Breathing also affected the feeling that the virtual body belonged to them almost as much as the character's appearance did. Breathing may also influence when people act. They are much more likely to press a button spontaneously during the later part of exhalation than during inhalation. One possible explanation is that exhaling reduces competition between the brain signals controlling breathing and those controlling movement.
Problems with breathing and lung health can also affect thinking. People who recovered from COVID-19 showed difficulties with attention, working memory and problem-solving. These problems became more severe as the amount of medical help they needed for breathing problems increased. In the most severe cases, their difficulties were greater than those caused by a stroke. Sleep-related breathing disorders were linked to a 26 percent higher risk of cognitive impairment. Lung transplantation can improve breathing, but it has also been associated with problems in planning, decision-making and verbal memory. Air quality matters as well. In a controlled study, office workers' scores on complex decision-making tasks improved by 61 percent in an environment with low levels of volatile organic compounds (VOCs). Their scores improved by 101 percent when low VOC levels were combined with high levels of outdoor air ventilation. As carbon dioxide levels rose, performance fell in a roughly straight-line pattern, by as much as 50 percent. Another study that followed workers for twelve months found that employees in buildings with more airborne particles and poorer ventilation performed worse on Stroop tests, which measure attention and control over automatic responses, and on arithmetic tasks.
The gut sends important signals of its own. In a water-load test, the ability to sense stomach activity was linked to better logical memory, which depends on the hippocampus. Researchers combined electroencephalography with electrogastrography and found that the brain's natural alpha rhythm changed in step with slow waves of activity in the stomach. This connection became weaker as people's view of their own bodies became more negative. Using wireless pills that could be swallowed, the researchers also found that people's sense of their own bodies in virtual reality was linked to gut activity. A more acidic stomach, a less acidic intestine or higher body temperatures were associated with a stronger sense of being located in one's body and a weaker feeling of being separated from it. Stomach acidity was also linked to emotions. People with higher stomach acidity felt stronger disgust and fear after watching emotional video clips. Other organs also appear to affect thinking. Up to half of people who receive a liver transplant develop problems with thinking after surgery. Chronic kidney disease can harm cognitive function through effects on blood vessels in the brain and through dialysis-related factors. Ovarian hormones, including estradiol, influence memory circuits in the hippocampus and prefrontal cortex. Excessive heat can also slow thinking and reduce working memory in young adults.
To bring these findings together, the authors suggest a theory they call 'deep embodiment.' It challenges brain reductionism, the idea that mental activity comes entirely from nerve cells and supporting glial cells in the brain. It also goes beyond 'shallow' theories of embodiment, which focus mainly on the body's outer parts. The authors argue that repeating signals from internal organs help connect thinking to a person's sense of self. Systole and inhalation appear to encourage a more self-centered way of thinking, with more self-focused behavior toward others, less social pain and a stronger sense that one's actions caused their results. Diastole and exhalation appear to encourage a less self-centered state. The authors call the balance between these states cognitive homeostasis. They also point out important limits to the evidence. Research into how internal body signals affect complex thinking is still at an early stage, and most studies show links rather than proving that one thing causes another. Standard tests that ask people to count their heartbeats have been criticized on methodological grounds, and few studies measure both conscious and unconscious forms of interoception at the same time. Future research could record signals from several organs together, use exercise, fasting, medicines or vagus nerve stimulation to test cause and effect, and develop artificial-intelligence digital twins of the heart and lungs to predict how people might think and behave in different physical states. From this point of view, the mind is not simply connected to the body. It is deeply shaped by it: it moves with the heartbeat, reacts to the gut and follows the rhythm of breathing.
Subject of Research: How activity in internal organs and the ability to sense it affect complex thinking and mental abilities
Article Title: The Mind From Within: Visceral Roots of Human Cognition
Article References: Monti, A., & Aglioti, S. M. (2026). The Mind From Within: Visceral Roots of Human Cognition. Advanced Science, 13(59), Article e24184. https://doi.org/10.1002/advs.202524184
Image Credits: AI Generated
Keywords: sensing internal body signals, brain responses to heartbeats, heartbeat cycle, breathing, gut-brain connection, memory, consciousness, social thinking, deep embodiment, voluntary action, organ transplantation, air quality