
Interoception is the collection of
senses
A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as su ...
providing information to the organism about the internal state of the body.
This can be both conscious and subconscious. It encompasses the brain's process of integrating signals relayed from the body into specific subregions—like the
brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...
,
thalamus
The thalamus (: thalami; from Greek language, Greek Wikt:θάλαμος, θάλαμος, "chamber") is a large mass of gray matter on the lateral wall of the third ventricle forming the wikt:dorsal, dorsal part of the diencephalon (a division of ...
,
insula,
somatosensory, and
anterior cingulate cortex—allowing for a complex and highly accurate representation of the physiological state of the body.
This is important for maintaining
homeostatic conditions
in the body and, potentially, facilitating
self-awareness
In philosophy of self, philosophy, self-awareness is the awareness and reflection of one's own personality or individuality, including traits, feelings, and behaviors. It is not to be confused with consciousness in the sense of qualia. While ...
.
Interoceptive signals are projected to the brain via a diversity of
neural pathway
In neuroanatomy, a neural pathway is the connection formed by axons that project from neurons to make synapses onto neurons in another location, to enable neurotransmission (the sending of a signal from one region of the nervous system to ano ...
s, in particular from the lamina I of the spinal cord along the spinothalamic pathway and through the projections of the
solitary nucleus, that allow for the sensory processing and prediction of internal bodily states. Misrepresentations of internal states, or a disconnect between the body's signals and the brain's interpretation and prediction of those signals, have been suggested to underlie conditions such as
anxiety
Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
, depression,
panic disorder,
anorexia nervosa
Anorexia nervosa (AN), often referred to simply as anorexia, is an eating disorder characterized by Calorie restriction, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin.
Individuals wit ...
,
bulimia nervosa
Bulimia nervosa, also known simply as bulimia, is an eating disorder characterized by binge eating (eating large quantities of food in a short period of time, often feeling out of control) followed by compensatory behaviors, such as self-indu ...
,
posttraumatic stress disorder
Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a Psychological trauma, traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster ...
(PTSD),
obsessive compulsive disorder (OCD),
attention deficit hyperactivity disorder
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple con ...
(ADHD),
alexithymia,
somatic symptom disorder, and
illness anxiety disorder.
The contemporary definition of interoception is not synonymous with the term "visceroception".
Visceroception refers to the perception of bodily signals arising specifically from the
viscera
In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...
: the heart, lungs, stomach, and bladder, along with other internal organs in the trunk of the body. This does not include organs like the brain and skin. Interoception encompasses visceral signaling, but more broadly relates to all physiological tissues that relay a signal to the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
about the current state of the body.
Interoceptive signals are transmitted to the brain via multiple pathways including the
lamina I spinothalamic pathway, the classical
viscerosensory pathway, the
vagus nerve
The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibe ...
and
glossopharyngeal nerve
The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper Medulla oblongata, medulla, just anterior (closer to the nose) to t ...
,
chemosensory pathways in the blood, and
somatosensory pathways from the skin.
Interoceptive signals arise from many different physiological systems of the body. The most commonly studied system is
cardiovascular
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart a ...
interoception which is typically measured by directing attention towards the sensation of the heartbeat during various tasks.
Other physiological systems integral to interoceptive processing include the
respiratory system
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...
,
gastrointestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...
and
genitourinary systems,
nociceptive system,
thermoregulatory system,
endocrine
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypotha ...
and
immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
s.
Soft cutaneous touch is another sensory signal often included within the interoceptive processing system.
History and etymology
Early to mid-1900s
The concept of interoception was introduced in 1906 by the Nobel Laureate
Sir Charles S. Sherrington. He did not use the noun ''interoception'', but did describe as ''interoceptive''
those receptors that are within the viscera—what are today called "visceroceptive"—and thus excluded all other receptors and information from the body, which he grouped as either ''exteroceptive'' or ''
proprioceptive''. In Sherrington's model, exteroceptive receptors were those that received information from outward stimuli, like light, touch, sound, and odor. He classified
temperature
Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...
and
nociception
In physiology, nociception , also nocioception; ) is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an organism to receive a pai ...
as exteroceptive sensations as well, though these are now regarded as having interoceptive qualities.
He further divided the internal milieu of the body by its
somatic and
autonomic functions. And proprioceptors were those found in
skeletal tissue that control voluntary movement. For him,
interoceptors (a term which has lost prevalence in modern literature) were thus confined to visceral involuntary
smooth muscle
Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...
(e.g. surrounding blood vessels).
Further work on interoceptive processing after Sherrington was delayed for many years owing to the influential claim by
John Newport Langley that the
autonomic nervous system
The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates viscera, internal organs, smooth muscle and glands. The autonomic nervo ...
used only
efferent (brain-to-body) signaling to implement its functions.
By the 1950s and 1960s, many investigations of interoceptive processing had been conducted, and once it had become apparent that interoceptive receptors are present in many tissues of the body other researchers began to investigate afferent body-to-brain signals, mainly by conducting animal experiments to see if interoceptive conditioning was possible. Using principles of
Pavlovian conditioning, different physiological systems in dogs were perturbed to elicit a conditioned response to food.
For example, in one experiment,
dogs' pelvises were distended using infusions of solution when food was presented to them. After rounds of pairing the two, salivation occurred without presenting food once the pelvis was distended.
Interoceptive conditioning studies like this illustrated that interoceptive sensations may be important for learned behavior and emotion.
Mid-1900s to 2000

The increased interest in interoception during the late 1950s and the 1960s, as evidenced by the number of papers published, has been referred to as the "
biofeedback
Biofeedback is the technique of gaining greater awareness of many physiology, physiological functions of one's own body by using Electronics, electronic or other instruments, and with a goal of being able to Manipulation (psychology), manipulate ...
blip". This was a phase during which many researchers examined humans' ability to gain control over
autonomic functions as a method of treatment for various conditions.
Interoception did not gain widespread popularity within the scientific community until the mid- to late-twentieth century. During that period, some researchers chose to use the terms ''visceroceptor'' and ''interoceptor'' interchangeably, in line with Sherrington's usage,
others combined proprioceptive and visceroceptive information into one category—interoception—based on physiological data about the lack of differences in
nerve impulses, and still others proposed that interoception includes more than just
endogenous
Endogeny, in biology, refers to the property of originating or developing from within an organism, tissue, or cell.
For example, ''endogenous substances'', and ''endogenous processes'' are those that originate within a living system (e.g. an ...
(internal) stimuli.
Exactly which sensory signals could or should be classified as interoceptive remains the subject of ongoing debate.
During the 1980s,
psychophysiologists began to extensively examine cardiovascular interoception, introducing several different experimental tasks for studying the perception of the heartbeat: heartbeat counting,
heartbeat tapping,
and heartbeat detection.
Psychiatrist
A psychiatrist is a physician who specializes in psychiatry. Psychiatrists are physicians who evaluate patients to determine whether their symptoms are the result of a physical illness, a combination of physical and mental ailments or strictly ...
s also began to look at the effects of pharmacological stimulation on the symptoms of
panic disorder. All of this further increased researchers' interest in interoception, including the development of theoretical models of the integration of interoceptive information within the body over time.
2000 and on
The twenty-first century has seen a tremendous increase in publications on the topic of interoception, and to a recognition of its multifaceted nature .
This has led to the emergence of different ideas about interoception. One contemporary definition widens the concept to encompass "the skin and all that is underneath the skin" and the perception and function of bodily activity
to more fully understand psychosomatic processes.
In a similar vein,
neuroanatomists hoping to find the anatomical basis of interoceptive functioning have stated the existence of a
homeostatic pathway from the body to the brain that represents "the physiological status of all tissues in the body," and that this mapping onto the brain provides an individual with subjective feeling states that are critical for human
emotion
Emotions are physical and mental states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavior, behavioral responses, and a degree of pleasure or suffering, displeasure. There is ...
and
self-awareness
In philosophy of self, philosophy, self-awareness is the awareness and reflection of one's own personality or individuality, including traits, feelings, and behaviors. It is not to be confused with consciousness in the sense of qualia. While ...
.
For example, interoception is the fundament of the modern view on
allostasis and
allostatic load
Allostatic load is "the wear and tear on the body" which accumulates as an individual is exposed to repeated or chronic Stress (biology), stress. The term was coined by Bruce McEwen and Eliot Stellar in 1993. It represents the physiological conseq ...
. The regulatory model of allostasis claims that the brain's primary role as an organ is the predictive regulation of internal sensations.
Predictive regulation is the brain's ability to anticipate needs and prepare to fulfill them before they arise. In this model, the brain is responsible for efficient regulation of its internal milieu.
Interoception is sometimes generally referred to as "the perception of internal body states"
although there are many interoceptive processes that are not consciously perceived. Importantly, interoception is made possible through a process of "integrating the information coming from inside the body into the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
". This definition deviates from Sherrington's original proposition, but exemplifies the dynamic and widening breadth of interoception as a concept in modern literature.
Facets of interoception

Although interoception as a term has more recently gained increased popularity, different aspects of it have been studied since the 1950s. These include the features of attention, detection, magnitude, discrimination, accuracy, sensibility, and self-reporting.
Despite not using the word ''interoception'' specifically, many publications in the
physiology
Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
and medical fields have focused on understanding interoceptive information processing in different
organ systems
An organ system is a biological system consisting of a group of organs that work together to perform one or more bodily functions. Each organ has a specialized role in an organism body, and is made up of distinct tissues.
Humans
There ar ...
. Attention describes the ability to observe sensations within the body, it can be directed voluntarily in a "
top down
"Top Down" is a song by American rapper and producer Swizz Beatz, included as the eighth track from his debut studio album ''One Man Band Man'' (2007). "Top Down" contains Sampling (music), samples of swirls and riotous bursts of 1970s-soul horns ...
" manner or it can be attracted involuntarily in a "bottom up" manner.
Detection reflects the presence or absence of a conscious report of interoceptive stimuli, like a heartbeat or growling stomach. Magnitude is the intensity of the stimulus, or how strongly the stimuli is felt. Discrimination describes the ability to localize interoceptive stimuli in the body to specific organs and differentiate them from other bodily stimuli that also occur, like distinguishing between a heart which is beating hard from an upset stomach. Accuracy (or sensitivity) refers to how precisely and correctly an individual can monitor specific interoceptive processes.
Self-reporting is itself multifaceted. It describes the ability to reflect on interoceptive experiences occurring over different periods of time, make judgments about them, and describe them.
Brain-body interactions can also be studied using neuroimaging techniques to map functional interactions between brain and peripheral signals. Although all of these components of interoception have been studied since the mid-twentieth century, they have not been brought together under the umbrella term "interoception" until more recently.
The term "interoceptive awareness" is also frequently used to encompass any (or all) of the different interoception features that are accessible to conscious self-report. This multifaceted approach offers a unified way of looking at interoceptive functioning and its different features, it clarifies the definition of interoception itself, and it informs structured ways of assessing interoceptive experiences in an individual.
Interoceptive physiology
Cardiovascular system
Cardiac interoception has been widely studied as a method of evaluating interoceptive sensation. This is done using different tasks including heartbeat counting,
heartbeat tapping,
heartbeat detection and heartbeat attention
tasks. Heartbeat counting tasks ask participants to count the number of felt heartbeats during short time periods. Their reported count is then compared with the actual count obtained with an
electrocardiogram. This measures the participant's attention to his or her own heartbeat, the accuracy with which that is perceived, and the ability of the participant to report that measurement. However, results can be influenced by the participant's preexisting knowledge of his or her heart rate and an insensitivity to heart rate change.
Heartbeat detection tasks work by providing a participant with a musical tone which is played simultaneously or non-simultaneously with one's heartbeat, asking the participant to report whether it is simultaneous or not with the tones. Heartbeat detection is commonly used because of its ability discern an individual's performance above chance levels, so-called "good detectors". However, such detection rates among participants for this task are usually only 35%.
It also measures the participant's attention, detection, discrimination, accuracy and self-report of the interoceptive process.
Heartbeat attention tasks are the most minimalistic, and involve simply the top-down direction of attention towards an interoceptive sensation such as the heartbeat, breath, or stomach.
Most perceptions of heartbeat sensations usually occur during a time of homeostatic perturbation, such as when the state of the body changes from external or internal influences such as physical exertion or elevated arousal states, e.g., riding a roller coaster, watching a scary movie, public speaking anxiety, or having a panic attack. For this reason, cardiac interoception is also sometimes studied by inducing perturbations of bodily state. This can be done pharmacologically using
adrenaline
Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands a ...
-like drugs, such as
isoproterenol, which mimic activation of the
sympathetic nervous system
The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...
,
resulting in increased heart rate and respiration rate, similar to the
"fight-or-flight" response. This approach provides a physiological basis for understanding
psychiatric and
neurological disorder
Neurological disorders represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These disorders affect the brain, spinal cord, and nerve networks, presenting unique diagnosis, treatment, and ...
s that are characterized by heightened
sympathetic nervous system
The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...
activity.
Respiratory and chemoreceptive system
Respiratory perception can differ from other interoceptive physiological symptoms because of an individual's ability to exert voluntary control over the system with
controlled breathing or breathing exercises.
This system is often measured using restrictive breathing loads and/or inhalation, which are designed to mimic
labored breathing sensations.
Dyspnea, or difficulty breathing, is a commonly felt sensation associated with panic attacks; however, due to the voluntary control of breathing, this domain of interoception usually requires implementation of much more elaborate experimental controls to quantify in comparison to cardiac interoception.
Gastrointestinal and genitourinary systems
Common interoceptive sensations related to the gastrointestinal and genitourinary systems are hunger and fullness. These are
homeostatic signals that tell an individual when to eat and when to stop eating. The dorsal mid-insula appears to be integral in taste processing during gastrointestinal interoceptive attention tasks. Rectal and bladder distensions are used as a method to perturb the homeostatic environment of the
gastrointestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...
and
genitourinary systems, using placement of
balloon catheters which can be inflated to achieve different stimulus intensities.
Associative fear learning paradigms have been used to study how innocuous signals might lead to abnormal states of gastrointestinal hypersensitivity and
anxiety
Anxiety is an emotion characterised by an unpleasant state of inner wikt:turmoil, turmoil and includes feelings of dread over Anticipation, anticipated events. Anxiety is different from fear in that fear is defined as the emotional response ...
.
Biofeedback
Biofeedback is the technique of gaining greater awareness of many physiology, physiological functions of one's own body by using Electronics, electronic or other instruments, and with a goal of being able to Manipulation (psychology), manipulate ...
therapy has been used for individuals with impaired gastrointestinal interoception, showing positive outcomes for some patients.
Nociceptive system
Nociception
In physiology, nociception , also nocioception; ) is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an organism to receive a pai ...
refers to the receiving and processing of pain inducing stimuli by the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
. Functional brain imaging studies during painful stimulation of the skin with heated probes, during mechanical compression, and electric shock have suggested that the
insular cortex
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere ...
is prominently activated during pain processing.
Thus while pain was once thought of as an exteroceptive sensation, based on functional imaging and anatomical evidence it is now understood that it has an interoceptive component.
Thermoregulatory system
Temperature and pain are thought to be represented as "feelings" of coolness and warmness and pleasantness or unpleasantness in the brain. These sensory and affective characteristics of
thermoregulation
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
may motivate certain behavioral responses depending on the state of the body (for example, moving away from a source of heat to a cooler space). Such perturbations in the internal
homeostatic environment of an organism are thought to be key aspects of a motivational process giving rise to
emotional states, and have been proposed to be represented principally by the
insular cortex
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal lobe, parietal and frontal lobes) within each brain hemisphere ...
as feelings.
These feelings then influence drives when the
anterior cingulate cortex is activated.
Endocrine and immune systems
The
endocrine
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypotha ...
and immune systems are necessary body systems that aid in allostasis and homeostatic control. Imbalances in these systems, along with other genetic and social factors, may be linked to interoceptive dysregulation in depression. These increased allostatic changes may cause a hyperawareness of interoceptive signaling and a hypo-awareness of exteroceptive signaling in depression patients.
Affective touch
Affective touch refers to the stimulation of slow, unmyelinated
C tactile afferents. This is accompanied by a sense of pleasantness, and has been likened to other interoceptive modalities like thermoregulation and nociception because of the similarities in anatomical function.
Soft touch activates the
insula rather than the
somatosensory cortex, indicating that it has an affective importance absent in
Aβ fibers. Since soft touch utilizes a separate pathway, it may have a social relevancy, allowing the body to separate the "noise" of outward stimuli from stimuli that evokes an affective feeling.
Neuroanatomical pathways
Multiple neural pathways relay information integral to interoceptive processing from the body to the brain. these include the lamina I
spinothalamic pathway, the visceroceptive pathway, and the
somatosensory pathway.
Lamina I spinothalamic pathway
The lamina I spinothalamic pathway is commonly known for carrying information to the brain about temperature and pain, but it has been suggested to more broadly relay all information about the homeostatic condition of the body.
* Afferent signals enter the spinal cord at the superficial layer of the
dorsal horn
* Second order neurons cross the midline of the
spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...
and project up the opposite side, synapsing on the
nucleus of the solitary tract,
parabrachial nucleus, and
periaqueductal gray in the
brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...
* Third order neurons in the
ventral posteromedial nucleus in the thalamus relay the signal to the dorsal posterior
insula
* The signal is re-represented on either the right or left side
Visceroceptive pathway
The visceroceptive pathway relays information about visceral organs to the brain.
* Afferent signals from the
vagus nerve
The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibe ...
enter the
brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is conti ...
making synaptic connections with the
nucleus of the solitary tract and
parabrachial nucleus
* The signal is relayed to the
ventromedial basal nucleus of the thalamus
* Third order neurons send the signal to the posterior
insula
Somatosensory pathway
The somatosensory pathway relays information about proprioception and
discriminative touch to the brain through different receptors in the skin.
* Afferent signals from the
mechanoreceptor
A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into action potential, electrical signals tha ...
s or proprioceptors enter the spinal cord at the dorsal root ganglia
* Second order neurons cross the midline in the medulla, projecting up the opposite side and synapse on third order neurons in the
ventral posterior lateral nucleus
The ventral posterolateral nucleus (VPL) is one of the subdivisions of the ventral posterior nucleus in the ventral nuclear group of the thalamus. It relays sensory information from the second-order neurons of the neospinothalamic tract and medial ...
or ventromedial posterior nucleus of the thalamus
* Third order neurons in the thalamus relay the signal to the
primary somatosensory cortex in the brain
Cortical processing of interoception
Thalamus
The thalamus receives signals from sympathetic and parasympathetic afferents during interoceptive processing. The
ventromedial posterior nucleus (VMpo) is a subregion of the thalamus which receives sympathetic information from lamina I
spinothalamic neurons. The human VMpo is much larger than that of primates and sub-primates and is important for processing of nociceptive, thermoregulatory, and visceral sensations. The
ventromedial basal nucleus (VMb) receives parasympathetic information from
visceral
In a multicellular organism, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization, hierarchy of life, an organ lies between Tissue (biology), tissue and an o ...
and
gustatory systems.
Insular cortex

The
insula is critically involved in the processing, integration, and cortical representation of visceral and interoceptive information. Lamina I spinothalamic and vagal afferents project via the brainstem and thalamus to the posterior and mid dorsal insula respectively. From there, information travels to the posterior and mid-insula, which combines visceral and somatosensory information.
The insula is also activated during a variety of exteroceptive and affective tasks. The insula is considered to be a "hub" region because it has an extremely high number of connections with other brain areas, suggesting it may be important for an integration of lower-level physiological information and
salience.
Anterior insular cortex
The anterior insular cortex (AIC) is involved in the representation of "cognitive feelings" which arise from the moment-to-moment integration of homeostatic information from the body. These feelings engender self-awareness by creating a sentient being (someone able to feel and perceive) aware of bodily and cognitive processing.
Essentially all subjective bodily feelings are associated with activation in the anterior insula: interoceptive feelings come to awareness in the anterior insula.
PET studies of cool feelings revealed that activiation that correlated with the subjective ratings of cool temperatures on the hand appeared first in the mid-insula, and then it was strongest in the right anterior insula and orbitofrontal cortex. Feelings from the body of heat pain or C-tactile affective touch also produce activation in the posterior, mid-, and anterior insula, and the strongest activation associated with these subjective feelings is in the anterior insula.
One study of heat pain explicitly showed that activation in the dorsal posterior insula correlated with objective painful heat intensity, whereas activation in the right anterior insula correlated with subjective pain intensity ratings. Similarly, subjective ratings of flavors and tastes correlates strongly with activation in the left anterior insula. The available evidence supports the interpretation that feelings from the body is engendered in the anterior insula.
Cytoarchitecture and granulation

The insula contains three major subregions defined by the presence or absence of a granule cell layer:
granular
Granularity (also called graininess) is the degree to which a material or system is composed of distinction (philosophy), distinguishable pieces, granular material, "granules" or grain, "grains" (metaphorically).
It can either refer to the exten ...
, dysgranular (slightly granulated)
agranular. Each of these portions of the insular cortex are important for different levels of functional connectivity. Information from the thalamus is projected to all three regions. Those with increased granulation are considered to be capable of receiving sensory input.
Anterior cingulate cortex
The
anterior cingulate cortex (ACC) plays a significant role in
motivation
Motivation is an mental state, internal state that propels individuals to engage in goal-directed behavior. It is often understood as a force that explains why people or animals initiate, continue, or terminate a certain behavior at a particul ...
and the creation of
emotion
Emotions are physical and mental states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavior, behavioral responses, and a degree of pleasure or suffering, displeasure. There is ...
. An emotion can be seen as comprising both a feeling and a motivation based on that feeling. According to one view, the "feeling" is represented in the insula, while the "motivation" is represented in the ACC.
Many interoceptive tasks activate the insula and ACC together, specifically tasks that elicit strong aversive feeling states like pain.
Somatosensory cortex
The
sensory motor cortex provides an alternative pathway for sensing interoceptive stimuli. Although not following the conventional pathway for
interoceptive awareness, skin afferents which project to the primary and secondary somatosensory cortices provide the brain with information regarding bodily information. This area of the brain is commonly engaged by gastrointestinal distension and nociceptive stimulation, but it likely plays a role in representing other interoceptive sensations as well.
In one study, a patient with bilateral insula and
ACC damage was given
isoproterenol as a method of exciting the
cardiovascular system
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart a ...
. Despite damage to putative interoceptive areas of the brain, the patient was able to perceive his heartbeat with similar accuracy compared to healthy individuals; however, once
lidocaine
Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type. It is also used to treat ventricular tachycardia and ventricular fibrillation. When used for local anae ...
was applied to the patient's chest over the region of maximum cardiac sensation and the test was run again, the patient did not sense any change in heartbeat whatsoever.
This suggested that somatosensory information from afferents innervating the skin outside of the heart may provide information to the brain about the heart's pounding through the somatosensory cortex.
Interoception and emotion
The relationship between interoception and emotional experience is an intimate one. In the late 19th century,
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
noted and discussed the involvement of sensations from the
viscera
In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...
by describing similarities between humans and animals reactions to fear in his book,
''The Expression of Emotions in Man and Animals''.
Later,
William James
William James (January 11, 1842 – August 26, 1910) was an American philosopher and psychologist. The first educator to offer a psychology course in the United States, he is considered to be one of the leading thinkers of the late 19th c ...
and
Carl Lange developed the
James-Lange theory of emotion, which states that bodily sensations provide the critical basis for emotional experience.
The
somatic marker hypothesis, proposed by
Antonio Damasio, expands upon the James-Lange theory and posits that decisions and the ensuing behaviors are optimally guided by physiological patterns of interoceptive and emotional information.
Ensuing models focusing on the neurobiology of feelings states emphasized that the brain's mapping of different physiological body states are the critical ingredients for emotional experience and
consciousness
Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...
. In another model,
Bud Craig argues that the intertwining of interoceptive and homeostatic processes is responsible for initiating and maintaining motivational states and engendering human self-awareness.
Interoception and illness
Interoception and mental illness
Disturbances of interoception occur prominently and frequently in psychiatric disorders. These symptom fluctuations are often observed during the most severe expression of dysfunction, and they figure prominently in diagnostic classification of several psychiatric disorders. A few typical examples are reviewed next.
Panic disorder
Palpitations
Palpitations occur when a person becomes aware of their heartbeat. The heartbeat may feel hard, fast, or uneven in their chest.
Symptoms include a very fast or irregular heartbeat. Palpitations are a sensory symptom. They are often described as ...
and
dyspnea are hallmarks of
panic attack
Panic attacks are sudden periods of intense fear and Comfort, discomfort that may include palpitations, otherwise defined as a Tachycardia, rapid, Arrhythmia, irregular Heart rate, heartbeat, Hyperhidrosis, sweating, chest pain or discomfort, s ...
s. Studies have shown that
panic disorder patients report a heightened experience of
interoceptive sensations, but these studies have failed to clarify whether this is simply due to their systematic bias toward describing such feelings. However, other studies have shown that panic disorder patients feel heartbeat sensations more intensely when the state of the body is perturbed by pharmacological agents, suggesting they exhibit heightened sensitivity to experiencing interoceptive sensations.
Generalized anxiety disorder
Patients with
generalized anxiety disorder
Generalized anxiety disorder (GAD) is an anxiety disorder characterized by excessive, uncontrollable and often irrational worry about events or activities. Worry often interferes with daily functioning. Individuals with GAD are often overly con ...
(GAD) frequently report being bothered by interoceptive feelings of muscle tension, headaches, fatigue, gastrointestinal complaints, and pain.
Posttraumatic stress disorder
Functional neuroimaging
Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions. It is primarily used a ...
studies have shown that
posttraumatic stress disorder
Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a Psychological trauma, traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster ...
(PTSD) patients exhibit a decreased activation in the right anterior insula, a region of the brain that is largely responsible for identifying the mismatch between
cognitive
Cognition is the "mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
and interoceptive states.
Further, because PTSD patients have shown decreased activation within many nodes of the lamina I homeostatic pathway—a pathway through which the thalamus sends interoceptive information to the
anterior insula and
anterior cingulate—it has been suggested that PTSD patients experience reduced interoceptive awareness.
Approaches such as
somatic experiencing use an interoceptive approach to treat PTSD.
Anxiety disorders
The broad consensus of studies investigating the link between interoceptive awareness and anxiety disorders is that people with anxiety disorders experience heightened awareness of and accuracy in identifying interoceptive processes. Functional imaging studies provide evidence that people with anxiety disorders experience heightened interoceptive accuracy, suggested by hyperactivation in the
anterior cingulate cortex—a region of the brain associated with interoception—in several different kinds of anxiety disorders. The insula has been suggested to be abnormal in a large scale study across anxiety disorders in general. Other studies have found that interoceptive accuracy is increased in these patients, as evidenced by their superior ability in heartbeat detection tasks in comparison to healthy controls.
Anorexia nervosa
Anorexia nervosa
Anorexia nervosa (AN), often referred to simply as anorexia, is an eating disorder characterized by Calorie restriction, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin.
Individuals wit ...
(AN) has been associated with interoceptive disturbances. Patients with AN often develop insensitivity to interoceptive cues of hunger, and yet are highly anxious and report disturbed interoceptive experiences, both inside and out.
While AN patients concentrate on distorted perceptions of their body exterior in fear of weight gain, they also report altered physical states ''within'' their bodies, such as indistinct feelings of fullness, or an inability to distinguish emotional states from bodily sensations in general (called
alexithymia).
Bulimia nervosa
Studies suggest that patients with and recovered from
bulimia nervosa
Bulimia nervosa, also known simply as bulimia, is an eating disorder characterized by binge eating (eating large quantities of food in a short period of time, often feeling out of control) followed by compensatory behaviors, such as self-indu ...
(BN) exhibit abnormal interoceptive sensory processing and reduced interoceptive awareness under resting physiological conditions. Specifically, patients with BN report reduced sensitivity to many other kinds of internal and external sensations, exhibiting increased thresholds to heat pain compared to healthy subjects and an increased gastric capacity. Neuroimaging literature suggests a pattern of abnormal interoceptive processing in patients with BN based on increased activity and volume in the insula and
anterior cingulate cortex—regions associated with interoception and taste processing—when looking at food.
Major depressive disorder
Major depressive disorder
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...
(MDD) has been theoretically linked to interoceptive dysfunction. Studies have shown that women with MDD are less accurate on heartbeat counting tasks than are men with MDD and that, in general, patients with MDD are less accurate at counting heartbeat than are patients with panic or anxiety disorders. However, patients with MDD do not always exhibit reduced cardiac interoceptive accuracy; depressed patients experiencing high levels of anxiety will actually be more accurate on heartbeat detection tasks than depressed patients with lower levels of anxiety.
Somatic symptom disorders
Patients with
somatic symptom disorders score lower on heartbeat detection tasks than healthy controls, suggesting that interoceptive accuracy is poor in psychosomatic disorders. It has also been found that patients with
psychosomatic disorders who are anxious or stressed report physical symptom discomfort at lower heart rates during exercise treadmill tests, implying poorer interoceptive distress tolerance in somatic symptom disorders with comorbid psychiatric conditions.
Obsessive compulsive disorder
Results from a study investigating the relationship between obsessive compulsive disorder (OCD) and internal body signals found that patients with OCD were more accurate on a heartbeat perception task than healthy controls and anxiety patients heightened interoceptive awareness.
Autism spectrum disorder
Patients with
autism spectrum
Autism, also known as autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by differences or difficulties in social communication and interaction, a preference for predictability and routine, sensory processing d ...
disorder (ASD) may have poorer interoceptive awareness than control subjects. It is hypothesized that this decrease in interoceptive accuracy is due to
alexithymia, which is often associated with ASD.
However, it has also been found that children with ASD actually show greater interoceptive sensitivity than control subjects when measured over a long period of time.
Further investigation into the relationship between interoception and ASD is needed in order to fully understand the interoceptive aspect of the disorder.
Interoception and other illness
Fibromyalgia
A 2024 study found that some
FM people had higher interoception signals.
Current theories of interoceptive processing
Embodied predictive interoception coding (EPIC)
The EPIC model proposes a method of understanding the brain's response to stimuli contrary to the classic "stimulus-response" model. The classical view of information processing is that when a peripheral stimulus provided information to the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
, it was processed in the brain, and a response was elicited. The EPIC model
deviates from this and proposes that the brain is involved in a process of
active inference, that is, assiduously making predictions about situations based on previous experiences. These predictions, when coupled with incoming sensory signals, allow the brain to compute a prediction error. Interoceptive prediction errors signal the occurrence of discrepancies within the body, which the brain attempts to minimize. This can be done by modifying the predictions through brain-related pathways, altering the body position/location in order to better align incoming sensory signals with the prediction, or altering the brain's method of receiving incoming stimuli.
Interoceptive prediction error signals are a key component of many theories of interoceptive dysfunction in physical and mental health.
Research and treatments

As attention on interoception increases among the scientific community, new research methods and treatment tactics are beginning to emerge. Because there currently is not a clear consensus as to what exactly interoception is, or the best ways in which to measure it, most research and questionnaires on the subject only measure individual facets of interoception. The convergence and interrelatedness of the questionnaire items between the constructs has been found to be low.
Ongoing research in interoception has shown the importance of perturbing interoceptive systems.
This allows researchers the ability to document the effects of non-baseline states, which occur during times of panic or anxiety. It also provides the participant the ability to gauge the intensity of sensations within the body. This can be done through pharmacological interventions, balloon distensions, or respiratory breathing loads depending on the interoceptive system of interest.
Another research method used to study interoception is specialized
flotation environments.
[Oaklander, Mandy. "Float Hopes". ''Time''. Time, n.d. Web. 29 June 2017.] Floating removes external stimuli so that individuals can more easily focus on the interoceptive sensations within their bodies. One idea with floating is that over many float sessions, patients with different kinds of disorders may learn to become more attuned or tolerant of their interoceptive sensations not only in the
float tank but also in their everyday lives.
Whole body
hyperthermia
Hyperthermia, also known as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme te ...
may provide a new treatment technique for
major depressive disorder
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...
. It is thought that reducing one of the bodily symptoms of depression, which is increased
inflammation
Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...
, using whole body hyperthermia will also reduce depressive feelings represented in the brain. In theory, these techniques will help patients better attune themselves to their interoceptive sensations, allowing them a better understanding of what occurs in their bodies.
Acupuncture
Acupuncture is a form of alternative medicine and a component of traditional Chinese medicine (TCM) in which thin needles are inserted into the body. Acupuncture is a pseudoscience; the theories and practices of TCM are not based on scientif ...
is an alternative treatment type for many people with anxiety and depression. Typically, it is self-prescribed by patients; however, results are inconclusive on its ability to manage symptoms of
depression. Recently,
Massage
Massage is the rubbing or kneading of the body's soft tissues. Massage techniques are commonly applied with hands, fingers, elbows, knees, forearms, feet, or a device. The purpose of massage is generally for the treatment of body stress or pa ...
therapy has been shown to have the ability to reduce symptoms of generalized anxiety disorder.
Meditation
Meditation is a practice in which an individual uses a technique to train attention and awareness and detach from reflexive, "discursive thinking", achieving a mentally clear and emotionally calm and stable state, while not judging the meditat ...
and
mindfulness have been looked into as possible techniques to enhance interoceptive awareness based on their tendency to redirect focus within oneself. Studies show that meditation and mindfulness practices promote attention to interoceptive sensations. In reality, with all the benefits of mindfulness, many may be ascribed to an increase in interoception. However, interoceptive awareness and accuracy in specific domains such as breath or body monitoring, may be more independent from a broad improvement in interoceptive accuracy. Meditation and mindfulness practices have been shown to modify the insula, which is considered central to our interoceptive abilities.
Attention is also being given to the
subtle body
A subtle body is a "quasi material" aspect of the human body, being neither solely physical nor solely spiritual, according to various Western esotericism, esoteric, occultism, occult, and mysticism, mystical teachings. This contrasts with th ...
and its function as a CNS map in traditional Tibetan and Indian medicine.
[Loizzo JJ. "The subtle body: an interoceptive map of central nervous system function and meditative mind-brain-body integration". ''Ann N Y Acad Sci.'' 2016 Jun;1373(1):78-95. . Epub 2016 May 10. .]
Although a universal definition of interoception has not been reached, research on interoception and
psychiatric disorders
A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
has shown a link between interoceptive processing and mental disorders. It has been proposed that
exposure therapy, a commonly employed treatment for
anxiety disorder
Anxiety disorders are a group of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal functions are significantly impaired. Anxiety may cause phys ...
s, may provide a basis for a model of
interoceptive exposure therapy that could be incorporated into treatment plans of different psychiatric disorders.
One proposal states that multiple interoceptive challenges assessing different physiological systems could provide diagnosticians with the ability to create an "interoceptive profile" for a specific individual, creating a patient-specific treatment plan.
See also
*
Inflammatory reflex
*
Proprioception
Proprioception ( ) is the sense of self-movement, force, and body position.
Proprioception is mediated by proprioceptors, a type of sensory receptor, located within muscles, tendons, and joints. Most animals possess multiple subtypes of propri ...
References
{{reflist
External links
Interoception Libraryat
Center for Open Science
Laureate Institute for Brain Research Interoception Summit 2016on YouTube
Human body
Human physiology
Human anatomy