How the Insular Cortex Works: 7 Functions of the Insular Cortex

The insular cortex (also known as the “insula”) is a structure located within the brain’s lateral sulcus, which separates the frontal and parietal lobes from the temporal lobe. The insula is covered by an operculum and split in two by the central insular sulcus, which divides it into the anterior and posterior insula. The anterior insula comprises short insular gyri, whereas the posterior insula is made of long insular gyri. This cortical hub connects different brain areas through a network of cortices and subcortices. For example, the insula connects with the anterior cingulate cortex (ACC), the orbitofrontal cortex, and the medial prefrontal cortex, as well as the limbic system, which includes the amygdala, thalamus, hypothalamus, and parahippocampal regions, all of which have their own roles within the structure of the brain.

There are a variety of functions associated with the insular cortex, such as:

1. 1. Sensory processing: The insula’s role extends to filtering and interpreting information taken in by the senses: sound, smell, taste, sight, and touch. The insula takes in auditory, olfactory, gustatory, visual, and somatosensory cues via thalamic and horizontal cortical afferents from inside the body (also known as interoception) to determine the senses we perceive. Interoceptive processes help you identify what’s happening in your body, including whether you are hungry or full, cold or hot, or have a full bladder.
2. 2. Motor control: Hand-eye coordination, the physical function of the gastrointestinal tract, and speech articulation are motor functions aided by the human insula. It also controls blood pressure and heart rate at the beginning of exercise.
3. 3. Self-awareness: The insula and other brain regions play an essential role in our sense of self. Our self-awareness and how we perceive our bodies, feelings, and the outside world are due to the insula’s functional connectivity, the anterior cingulate cortex, and the medial prefrontal cortex.
4. 4. Decision-making: Some neuroimaging studies have established a link between damage to the insula and a person’s ability to weigh the values of choices to make the right decision.
5. 5. Nervous system functionality: The insula is involved in a variety of autonomic functions. Homeostasis, or physiological stability, is controlled by the insula, as well as immune system regulation.
6. 6. Emotion: Functional magnetic resonance imaging (fMRI) studies have shown that the insula plays a vital role in the emotions we feel, such as happiness, sadness, disgust, fear, and anger. Specifically, the anterior insular cortex (AIC) is responsible for feelings like trust, resentment, sexual arousal, love, and disbelief. It is also responsible for social cognition that helps us generate empathy—our ability to relate to others on an emotional level. Scientific studies have shown that the insula plays a major role in the process of feeling emotions, and the brain stem may factor into how we experience feelings.
7. 7. Conscious desires: Brain imaging studies show a link between emotional states and how they change the body. Since the insula is heavily involved in processing the information related to our bodily conditions, it also plays a role in our cravings.

Due to the insula’s deeply embedded location within the brain, it has long been challenging to study. However, in more recent years, there have been some successful studies showing how faulty activation of the insula (due to damage or lesions) correlates to a change in a person’s emotional processing and behavior:

1. 1. Sensory problems: Insular cortex damage can cause a wide array of issues to sensory perception. People with a malfunctioning insula will still experience their senses, but may not generate an appropriate response to them. For instance, taste aversion, which is our body’s way of telling us to avoid foods that might be bad or poisonous, may be affected by insula damage. The insula may also impact the ability to generate an appropriate response to feeling pain.
2. 2. Lack of judgment: Those with impairment to their insular cortex show an abnormal expression of trust. For example, they cannot recognize risk and judge others correctly, often placing trust in untrustworthy people and not trusting (or violating) someone they should.
3. 3. Insular epilepsy: One of the leading causes of epilepsy is a malfunction of the frontal or temporal lobe. In rare cases, the insula may be responsible for an occurrence of epileptic seizures, making it difficult to treat, as surgeries to the temporal or frontal lobe are usually unsuccessful in mitigating the symptoms of insular epilepsy.
4. 4. Frontotemporal dementia (FTD): People with FTD often experience a loss of empathy, repetitive, compulsive behaviors, lack of inhibition, poor judgment, speech changes, and inappropriate social behavior, processes aided by the insular cortex. This condition may be due to atrophy or degeneration of the dorsal and ventral insula, along with the anterior cingulate cortex (ACC), and a network of other cortical areas.

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