The insula (or 'island of Reil') is a part of the brain that is deeply folded in the lateral sulcus (Silvian fissure or fissura lateralis), below the surface of the brain on the side. The lateral sulcus is the large ditch between the sleeping lobe, the frontal lobe and wall bone lobe (see picture on the right).

It can be divided into three portions of which the front and the rear part are the best known. The front part is called anterior insular cortex; AIC or simply anterior insula and the posterior is the posterior insula.



By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below) Gray's Anatomy, Plate 731, Public Domain, php? curid = 527111


The left brain lobe cut open to see the insula. Part of the frontal and temporal lobe have been removed in this image.

The Sylvian fissure or lateral sulcus behind which lies the insula.


What does the insula do?

The insula appears to be the brain area where sensory experiences are merged into the emotional context. It is part of the limbic system. The brain areas of the limbic system are involved in emotion, emotional memory, motivation and pleasure. It is also involved in many functions.

The front part of the insula (anterior insula) is related to involuntary control of the intestines, smell, taste, emotion, emotional pleasure, motivation and emotional memory.


The posterior insula is related to sound (auditory function), touch and proprioception / balance (self-perception of how and where your body is or lies through the skeleton and thourgh muscle functions).


The insula is involved in multiple functions and immediately receives information from many areas of the brain, including the thalamus and amygdala and cerebral cortex. In turn, it sends information back to the amygdala, orbitofrontal cortex and ventral striatum.


It is involved in:

  • emotion and motivation
    • disgust
    • fear, surprise, joy and anger
    • emotional awareness, conscious experience of emotions
  • social skills, observing social signals, empathy
  • sense of self, self-awareness, knowing that you are a unique being
  • addiction and compulsive behavior, emotional aspects of an experience
  • speech and language
  • learning by hearing and associating with sound (learning music, learning to speak languages)
  • movements in swallowing, gastric peristalsis, speaking and hand-eye motor skills
  • control of autonomous functions by controlling sympathetic and parasympathetic systems
  • self-awareness on a physical level, awareness of physical information such as pain, heartbeat and body temperature, oxygen status, itching, a full bladder, swollen stomach or stomach and sensual touch, functions related to survival needs. The official words for this are homeostasis and interoception.
  • pain and pain experience, gauge of pain and empathy with pain from others.


Emotion, social skills, empathy and self-awareness

The insula is part of the limbic system that as a whole is involved in emotion and motivation (together with the fornix, amygdala, parts of the thalamus).


The insula, like other areas, is involved in basic emotions such as fear, anger, joy, surprise and sadness, but the insula is the only part of the brain that is active in disgust, according to research. It is also involved in empathy, being able to sympathize with someone else. Furthermore, the emotional consciousness, conscious experience of emotions is set here.

This emotional awareness also means that you can experience that you are a unique being (yourself).


Addiction and compulsive behavior

The insula is involved in addiction and especially in the emotional memory and the conscious feelings (urges) of addiction, which form an important part of an addiction. If someone is addicted, the person is reminded of the drugs if he or she arrives somewhere where the drugs are sold or used. There are stories of smokers who had an acute aversion to smoking and of cigarette smoke due to injuries in the insula.


Speach and language

The insula is part of a linguistic network involved in producing speech and processing language. (Along with the inferior frontal and lateral frontal areas and prefrontal cortex and frontal operculum). Research showed that in bilinguals or multilingualism the insula was thicker, making learning a foreign language easier. It seems to form 'the language lump'.
Injury in this area can give a form of Broca aphasia.


Body information awareness, homeostasis and interoception

The insula receives information from the thalamus and processes this information about the condition of the body, for example how quickly the heart beats, how high the blood pressure is and how the body temperature is, whether you are short of breath and makes it available for emotional and thought processes (homeostasis).


Knowing that the heart rate is rising or observing an increased body temperature is important information for survival. This makes the person aware of tension or the fact that he / she probably has a fever. The insula forwards the information to various structures associated with the limbic system.
Interoceptive awareness is also in the insula, that is the ability to perceive stimuli, signals from within the own body. This includes feeling thirst and a full bladder or feeling your heart pounding in your throat. Signals that sometimes scream for attention and can also overstimulate. The interoceptive sensory system is divided over various intestines.

Pain and pain experience

The insula is also involved in pain and pain experience. Chronic pain can alter the anatomical and functional structures of the insula, which can disrupt thinking and prolonged emotional state (cognitive and affective disorders). For example, this is the case with depression due to pain. Pain can also be influenced and changed by mood, attention and cognition.


Consequences of injury in the insula

  • Lack of disgust,
  • Change or the disappearance of an addiction,
  • Compulsive behavior
  • Difficulty in articulating, speaking fluently
  • Foreign accent syndrome
  • Disruption of awareness of physical conditions that are important to survive, such as heart rate increase, fever, hunger, thirst etc.
  • Disturbance in ability to perceive emotions and understand social situations
  • Disturbance of the sense of self, perception as a unique being, inability to express emotions (alexithymia)
  • Disruption of linking emotion to sensory experience, disruption of perception of pain



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The brain from top to bottom

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