Do you consider yourself to be emotionally intelligent? Are you empathic, able to read other people's feelings even when they try to hide or swallow them? Or do friends rib you about your social cluelessness? Do people see you as spiritually grounded, emotionally balanced, a rock? Or do they say youre repressed, tactless, juvenile? If you werent in good touch with your own emotional inner world, how would you ever know?

Several years ago nine women and eight men came to Hugo Critchley's laboratory at the Institute for Cognitive Neuroscience at University College London to explore their level of emotional sensitivity. Critchley, an expert on brain mapping who is now at the University of Sussex in England, was interested in the relation between emotional intelligence and a brain function called interoception--your ability to read and interpret sensations arising from within your own body.

Pretend you are a participant in such an experiment. You lie down in a brain scanner, put on headphones and place your left middle finger on a pad that monitors your heart rate. Your right hand rests on another pad with two buttons. As the scanner monitors your brain activity, you listen through the headphones to several series of 10 beeps. After each 10-beep sequence there is a pause, and you are asked to make a choice: press one button if you think the beeps were in time with your own heartbeats or press the other button if you think the beeps were slightly out of sync with your heart. Critchley repeats these sequences, sometimes in sync, sometimes not. Can you tell the difference?

Four of Critchley's subjects were supremely confident about when the pulse was synchronous or asynchronous with their heart. They could feel the difference, accurately, every time. Two subjects were veritably heart-blind. They never had a clue about whether the pulses were in or out of sync and could only guess at random. The others fell in between.

The brain scans revealed significant activity in several brain regions, notably the insula and anterior cingulate cortex. Both these regions are crucial centers of emotional cognition, and as this study makes clear, they are also necessary for attending to feelings that arise from your body.

But the most significant finding in Critchley's study involved just one brain region, the right frontal insula. This area showed the greatest activity in those who were best at following their heartbeats. Moreover, these were the people who scored highest on a standardized questionnaire to probe their empathy levels. So the better you are at tracking your own heartbeats, Critchley says, the better you are at experiencing the full gamut of human emotions and feelings. The more viscerally aware, the more emotionally attuned you are.

In a follow-up study, Critchley found that people with greater empathy have more gray matter in their right frontal insula. That is, the thicker this part of your insula, the better you are at reading feelings in yourself and in others. The fact that some people are more emotionally aware than others has a neural, physical basis.

Internal Maps
These experiments are a window into some of your most important and fascinating body maps--those that deal in interoception and emotion. (Just as a road atlas is full of maps that represent real-world locations, your brain is full of body maps that represent aspects of your self, inside and out.) In contrast, the main goal of exteroception, externally oriented perception, is to create maps and models of your body, the world around your body, and your body's relation to the world. Your brain creates and maintains maps of your skin surface, limb position, joint movement and musculoskeletal system so that you can move about and interact with objects and people. You have distinct fibers in your spinal cord that carry such information in both directions: up from your body to your sensory maps and back down from your motor maps to your muscles.

Interoception is a separate realm of somatic sensation that is oriented inward. It has two sources. The first is the internally mapped state of your body. Bring your attention to the sensations these maps are generating in you right at this moment. Think about your heart, lungs, stomach, intestines, rectum, larynx, throat. Try to feel their activity if you can. All your innards have receptors that send information up to your brain for mapping your "gut" feelings of hunger, thirst, air hunger and other visceral sensations.

The second source of your interoceptive maps consists of a different class of receptors found on your body's surface, including your teeth, gums and tongue. Unlike the touch receptors that deal in pressure and vibration and are tied mainly to deliberate touch and action, these other receptors carry information about the "homeostatic" condition of your body--temperature, pain, itch, muscle ache, sexual arousal, crude touch and sensual touch. Homeostasis refers to your body's ability to maintain internal balance. Your spinal cord contains an evolutionarily older set of fibers that carries this information to and from your brain.

This may seem strange at first, because many of your body parts end up being mapped by both systems. If someone pinches your arm, the pressure and pain will be represented in your primary touch map. But the pain will be rerepresented in your insula. Why is pain from one pinch mapped in two places? Because your insular maps serve a different function from your primary touch and motor maps. They are the command center for homeostatic self-regulation. For example, to run your body's thermostat properly--to keep your body temperature constant--your brain needs to know not just about your core temperature but also about air touching your skin. Pain in your muscles, lungs and joints is important for marshaling your body's resources during exertion, but so are sensations of strain and movement and resistance in your joints and skin. So the primary brain maps for homeostatic signals from your body surface--about itch, sharp pain, dull pain, burning pain, tickle, sensual touch, heat and cold--as well as the sensations arising from your body's interior, are mapped in your insula, not in your primary touch cortex. You use these feelings less to deal with the outside world than to seek balance within your body and put your internal sensations in context.

And as Critchley's results imply, interoception does far more for you than just letting you know you are hungry or exhausted or sexually sated. It is also a crucial ingredient in some of the most important aspects of human beingness: sentiment, sentience and emotional awareness.

The Sting of a Bee and of a Rebuke
Your interoceptive maps are a souped-up version of neural circuitry that had already become highly advanced in the primate line. In lower vertebrates--a frog, say--sensory information is integrated in the primitive base of the brain. These animals do not have a cortex, the mantle of higher thought and awareness. So a frog's vision, for example, is extremely primitive and robotic in function. It is keyed to buglike motions made by small, dark, dotlike objects. When the frog "sees" such a stimulus, a targeted tongue attack reex is triggered. This is just about the only way the frog has to visually identify its food. When a frog is placed in a terrarium and surrounded by dead insects suspended on strings, it will starve to death. Its cortex-free vision just does not have the power to recognize individual features of its prey, such as legs or wings.

The greatest evolutionary innovation of mammals was the expansion of the cortex to tremendous size. The cortex imbues the mammalian mind with the capacity to form highly detailed and versatile representations of sights, sounds and actions. So a rat, for example, has a rich understanding of the space around its head, thanks to its sensitive whiskers and well-developed body and whisker maps. And even though rats do not have particularly good vision, they can still tell an insect from a wad of used dental oss at a glance because they have cortical vision maps.

But in the rat--and, for that matter, in all other mammals aside from primates--the homeostatic information from the body does not form a rich interoceptive map in the insula. Rats do have insular maps, to be sure, but they are rudimentary. In a rat, pain, itch, sensual touch and that whole ancient group of somatic senses are primarily integrated in the base of the brain and in subcortical emotional centers. Their interoception, then, is more reminiscent of the frog's automatonlike vision than of the primate's keen, knowing eye.

The same goes for cats, dogs, horses and other four-legged animals. Because of this difference in mapping, some experts claim that their sensory experiences must be profoundly different from ours, even though we are often tempted to attribute human emotions and intentions to our pets. Whereas a dog may show "shame" through its body language, it does not feel what you feel when you are ashamed. Dogs are clearly emotional and self-aware, but they are not in the same league as you.

In primates, interoceptive information is elaborated through a rich set of mappings in the insular cortex. And in humans, it is richer still. Thus, you have a little insular map for sharp pain, another for burning pain, one for itching, one for aching, one for overexerted muscles, and so on, along with visceral homunculi (body maps) that represent the state of your lungs, heart and the rest of your innards.

And even that is just the beginning of what your brain does with this information. After reading off the internal state of the body from both the left and right insulas, the human brain--and only the human brain--performs yet another level of integration. The information from both your insulas is routed to the right frontal insula, the same region Critchley found to correspond closely in size and metabolic vigor to a person's empathic talent.

Your right frontal insula "lights up" when you feel all the quintessential human emotions--love, hate, lust, disgust, gratitude, resentment, self-confidence, embarrassment, trust, distrust, empathy, contempt, approval, disdain, pride, humiliation, truthfulness, deceit, atonement, guilt. It also lights up when you feel strong sensations, from physical pain to a uttery stomach to tingling loins.

If your right frontal insula is damaged by a stroke, you will not be able to detect or feel disgust. If you look at someone who takes a bite of food, spits it out, and makes a retching sound with a disgusted look on his face, you will just smile, take a bite of the same food, and declare it delicious.

This dual physical-emotional sensitivity is not just a coincidence. The right frontal insula is where conscious physical sensation and conscious emotional awareness co-emerge. Consider this amazing fact: the right frontal insula is active both when you experience literal physical pain and when you experience the psychic "pain" of rejection or the social exclusion of being shunned. It lights up when you feel someone is treating you unfairly. Scanning experiments have proved all this, and the results are profound.

Reason Runs Hot
Arthur "Bud" Craig is a neuroanatomist at the Barrow Neurological Institute in Phoenix and the first person to figure out how interoception is uniquely wired in the human brain. He is the kind of superintense scientist who unapologetically spouts rapid-fire jargon--ventrolateral prefrontal cortex, solitary tract nucleus, posterior ventral medial nucleus. But for those who listen and translate, Craig is telling a story that drastically revises our scientific understanding of how bodily sensations are mapped in the human brain and turned into feelings, motivations, pain and sentience.

The right frontal insula is the focal point of all this activity, according to Craig, because it literally connects the state of your body to the state of your brain. By "your brain," in this context, he means the sensory perceptions, abstract thoughts, linguistic processing and motivations that occur elsewhere throughout your cortex. Your right frontal insula gives rise to the map of "the emotional me" and "the emotional now" by integrating homeostatic information from both your body and your brain. This is a profoundly important insight. You detect the state of your body and the state of your mind together in the right frontal insula. It is here that mind and body unite. It is the foundation for emotional intelligence.

If your mirror neurons are activated by another person's emotional state, your right frontal insula lights up. [For more on mirror neurons, see "A Revealing Reflection," by David Dobbs; Scientific American Mind, April/May 2006.] If you sense fear in a crowd, crave drugs or see someone cheat, your right frontal insula lights up. If you have schizophrenia, your right frontal insula is deformed.

Your right frontal insula integrates your mind and body through strong connections with three other brain regions. One is the amygdala, a lower brain area that plays a key role in linking strong emotions to experiences, people and things. Another is the orbitofrontal cortex, a region that is critical for self-discipline and for setting plans and priorities in relation to rewards and punishments. And finally, it is linked to the anterior cingulate cortex, which allows you to monitor your behavior for mistakes, correct and avoid errors, evaluate context, and plan and carry out actions that have emotional and motivational significance. The anterior cingulate also contains a mapping of your body, with your head at one end and your feet at the other, but so far as is known, the orbitofrontal cortex and amygdala do not.

In every brain-imaging study ever done of every human emotion, the right frontal insula and anterior cingulate cortex light up together, Craig says. He takes this to mean that in humans, emotions, feelings, motivations, ideas and intentions are combined to a unique degree, and that this is a key element of our humanity.

Actually, the idea that we sense our emotions from our bodies has been around for more than a century. Two psychologists, William James and Carl Georg Lange, long ago developed a theory that emotion arises when you perceive changes in your body. When you run from a bear in the woods, you are afraid not because of your rational assessment that you are about to be eaten but because your heart is racing, your stomach and sphincter are clenched, and you are running as fast as you can. In the wake of an argument, as long as your heart is still racing you still feel angry. There is an aspect of this that has bearing on many relationships: in women, according to Stanford University neuroscientist Robert Sapolsky, the autonomic nervous system ramps down more slowly than in men. As Sapolsky likes to say to his wife after a spat, "Honey, dont forget the half-life of the autonomic nervous system!"

This theory explains why people with whole-body paralysis often complain that their passions and emotions have become blunted. It is why psychopaths, who often have trouble feeling sensations from their body, feel no guilt, remorse or anxiety about their actions. It is also why taking a beta blocker--a drug that quiets your sympathetic, or "fight or flight," nervous system--can banish the butteries from your stomach, still your quivering limbs, turn off your drenching stage-fright sweats, and allow you to speak or perform calmly in public. In other words, the fear is more in your body than in your mind. Dampen your interoceptive signals, and you dampen the fear.

Antonio R. Damasio, a neuroscientist who heads the Brain and Creativity Institute at the University of Southern California, has updated and revised James and Lange's idea with his somatic marker hypothesis--the notion that your feelings strongly contribute to even the most "rational" decision making in everyday life. Scientists used to assume that reason and emotion were qualitatively different psychic spheres. Clearly, these spheres could inuence each other, yet most believed that the thinking, knowing, reasoning part of the mind was in some fundamental way distinct from the mind's feeling, sensing, emotional and more primitive aspects. But James and Lange, and now Damasio, Craig and others who follow the neuroscience, argue that it is just not possible to separate them at a deep level.

Emotion is never truly divorced from decision making, even when it is channeled aside by an effort of will. Even a mathematician pursuing the trail of a new proof is driven by a blend of personal ambition, curiosity and the sometimes spine-tingling Platonic beauty of the math itself. Even a judge who renders a verdict that the law supports but that he finds personally distasteful is being driven by a moral emotion about the principle of the rule of law. Even a terrorist coolly gearing up for a suicide attack is spurred by an intensely felt motivation inspired by his love of God and God's favored people, who also happen to be his own.

Interoception, then, is the font of your complex emotionality. It breathes life into your cortex, which is otherwise rather machinelike in character. Interoception is the fire under the kettle of consciousness; remove the heat, and the system settles into tepid equilibrium.