The insular cortex, also known as the insula and insular lobe, is a portion of the cerebral cortex folded deep within the lateral sulcus.

It sits in the fissure separating the temporal lobe from the parietal and frontal lobes, within each hemisphere of the mammalian brain.

The insulae are involved in consciousness and play a role in diverse emotions or the regulation of the body’s homeostasis. 

The insula is critically involved in the processing, integration, and cortical representation of visceral and interoceptive information. 

The insula is a hub region because its  an high number of connections with other brain areas, suggesting it may be important for an integration of lower-level physiological information and salience.

Its functions include compassion and empathy, taste, perception, motor control, self-awareness, cognitive functioning, and interpersonal experience. 

The insula is involved in psychopathology.

The insular cortex is divided into two parts: the anterior insula and the posterior insula.

The cortical area overlying the insula toward the lateral surface of the brain is the operculum.

The opercula are formed from parts of the enclosing frontal, temporal, and parietal lobes.

The anterior part of the insula is subdivided by shallow sulci into three or four short gyri.

The anterior insula receives a projection from the basal part of the ventral medial nucleus of the thalamus and a large input from the central nucleus of the amygdala. 

The anterior insula itself projects to the amygdala: to the anterior amygdaloid area as well as the medial, the cortical, the accessory basal magnocellular, the medial basal, and the lateral amygdaloid nuclei.

The posterior insula projects to the dorsal aspect of the lateral and to the central amygdaloid nuclei. 

The posterior part of the insula is formed by a long gyrus.

The posterior insular connects in a reciprocal fashion with the secondary somatosensory cortex and receives input from spinothalamically activated ventral posterior inferior thalamic nuclei. 

The posterior insular receives inputs from the posterior part of the thalamus highly specialized to convey homeostatic information such as pain, temperature, itch, local oxygen status, and sensual touch.

The  anterior insula is interconnected to regions in the temporal and occipital lobe, opercular and orbitofrontal cortex, triangular and opercular parts of the inferior frontal gyrus. 

The ‘circular sulcus of insula’ separates the insula from the neighboring gyri of the operculum in the front, above, and behind.

The insular cortex is considered a separate lobe of the telencephalon by some, the  temporal lobe, or as a limbic lobe by others.

Functional imaging studies indicate  activation of the insula during audio-visual integration tasks.

The anterior insula is part of the primary gustatory cortex.

The anterior insular cortex (AIC) represents  cognitive feelings which arise from the moment-to-moment integration of homeostatic information from the body. 

The spindle neurons in the right frontal insular cortex are also found in the anterior cingulate cortex are involved in cognitive emotional processes such as empathy and emotional feelings. 

The right frontal insula function is correlated with the ability to feel one’s own heartbeat, or to empathize with the pain of others.

The insula in conveys homeostatic information to consciousness.

The right anterior insula aids interoceptive awareness of body states: timing  one’s own heartbeat. 

Right anterior insular gray matter volume correlates with increased accuracy in the sense of the inner body, and with negative emotional experience, and is involved in the control of blood pressure, in particular during and after exercise.

Right anterior insular gray matter activity correlates  with the amount of effort a person believes he/she is exerting.

The Lamina I spinothalamic and vagal afferents project to the brainstem and thalamus and to the posterior and mid dorsal insula respectively. 

The posterior and mid-insula, contain information which combines visceral and somatosensory information.

The insula is also activated during a variety of exteroceptive and affective tasks. 

The insular cortex judges sensation of pain and its degree.

The insula is where one imagines pain when seeing images of painful events and  thinking about their happening to one’s own body.

In patients with irritable bowel syndrome there is. abnormal processing of visceral pain in the insular cortex related to dysfunctional inhibition of pain within the brain.

The right anterior insula perceives the degree of nonpainful warmth or nonpainful coldness of a skin sensation. 

Internal sensations processed by the insula include stomach or abdominal distension, and a full bladder also activates the insular cortex.

The perception of dyspnea is processed in the right human anterior insula and amygdala.

The cerebral cortex processes vestibular sensations that extend into the insula: small lesions in the anterior insular cortex being able to cause loss of balance and vertigo.

Other noninteroceptive perceptions of the insula include passive listening to music, laughter, and crying, empathy and compassion, and language.

The insula contributes to hand-and-eye motor movement, swallowing, gastric motility, and speech articulation.

The insula is a central command site that ensures that heart rate and blood pressure increase at the onset of exercise.

Its capacity includes that of long and complex spoken sentences, motor learning, and motor recovery from stroke.

It maintains a role in homeostatic functions related to basic survival needs,: taste, visceral sensation, and autonomic control. 

The insula controls autonomic functions through the regulation of the sympathetic and parasympathetic systems..

It helps regulate the immune system, and  has a role in the experience of bodily self-awareness, sense of agency, and sense of body ownership.

The anterior insula processes the sense of disgust to smells and to the sight of contamination and mutilation: even if just imagining the experience.

The insula allows an association  with a mirror neuron-like link between external and internal experiences.

The insula is involved in the processing of norm violations, emotional processing, empathy, and orgasms.

The insula is active during social decision making. 

Individuals with high emotional intelligence functional MRI scores have left insular activation when processing fearful faces, individuals with low scores had left insular activation when processing angry faces.

The insular cortex, is limbic-related.  

The insula has a major role in body representation and subjective emotional experience. 

The  anterior insula is related more to olfactory, gustatory, viscero-autonomic, and limbic function, whereas the posterior insula is related more to auditory-somesthetic-skeletomotor function. 

Functional MR imaging experiments have revealed that the insula has an important role in pain, emotions, including anger, fear, disgust, happiness, and sadness.

The anterior insular cortex is responsible for emotional feelings, including maternal and romantic love, anger, fear, sadness, happiness, sexual arousal, disgust, aversion, unfairness, inequity, indignation, uncertainty, disbelief, social exclusion, trust, empathy, sculptural beauty, a Union with God, and hallucinogenic states, and implicated in conscious desires, such as food craving and drug craving.

The insula effects emotional states is that change the body in some way and are associated with highly salient subjective qualities. 

The insula integrates information relating to bodily states into higher-order cognitive and emotional processes. 

The insula receives information from afferent sensory pathways via the thalamus and sends output to a number of other limbic-related structures, such as the amygdala, the ventral striatum, and the orbitofrontal cortex, as well as to motor cortices.

The right anterior insula is significantly thicker in people that meditate.

There is increased grey matter concentrations in this and other areas of the brain in experienced meditators.

The insula is involved in two types of salience. 

Interoceptive information processing that links interoception with emotional salience to generate a subjective representation of the body. 

There is a general salience network : environmental monitoring, response selection, and skeletomotor body orientation that involves all of the insular cortex and the mid-cingulate cortex.

The insular cortex is involved in auditory perception, and response  to the emotional contents of the auditory stimuli.

Progressive expressive aphasia is the deterioration of normal language function that causes individuals to lose the ability to communicate fluently while still being able to comprehend single words and intact other non-linguistic cognition. 

Progressive expressive aphasia is found in degenerative neurological conditions including:  Pick’s disease, motor neuron disease, corticobasal degeneration, frontotemporal dementia, and Alzheimer’s disease. 

Progressive expressive aphasia is associated with hypometabolism, and atrophy of the left anterior insular cortex.

The  insular cortex is activated when drug users are exposed to environmental cues that trigger cravings. 

Cigarette smokers with damaged insular cortices, have their addiction to cigarettes practically eliminated. 

There is a significant role for the insular cortex in the neurological mechanisms underlying addiction to nicotine and other drugs.

The insula is activated during the administration of addictive psychoactive drugs, and is activated when drug users are exposed to drug cues, and that this activity is correlated with subjective urges. 

The insula may play a role in memory for the pleasurable interoceptive effects of past drug use, anticipation of these effects in the future, or both. 

Insula effects may give rise to urges that feel as if they arise from within the body, and make addicts feel as if their bodies need to use a drug.

A damaged Insula may result in persons reporting that their bodies have forgotten the urge to use dugs.

The anterior insula, a part of the brain involved in interoception, self-reflection, and in avoiding uncertainty about uncertainty or risk.

The insular cortex has been suggested to have a role in anxiety disorders, emotion and anorexia nervosa.

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