The Insular Cortex Dopamine Center and Its Relationship to Parkinson’s
The idea for the title of my column, “Possibilities with Parkinson’s,” arose from my attempts to understand what was happening to me.
Because I do not display the dramatic motor symptoms of Parkinson’s disease, but have many of the non-motor symptoms, I seek out research that can help explain what I am experiencing. Medical providers who don’t see the classic symptoms often shut down conversations about what is going on in my brain and in my body. It is time for me to take control.
While researching dopamine neurons, I found a new MRI technique out of the Massachusetts Institute of Technology that showed whole brain dopamine utilization. While looking at dopamine release, when the whole brain is scanned, it becomes clear that dopamine affects two cortex regions most significantly.
The first region gives us the classic symptoms involving the motor cortex and connecting midbrain structures. The second is the insular cortex. When not functioning properly, the insular cortex can result in many of the non-motor symptoms associated with Parkinson’s, including many that I experience.
The researchers at MIT are not the first to link the insular cortex to dopamine and Parkinson’s symptoms. A 2014 summary published in the journal Brain about the connection to non-motor Parkinson’s symptoms states that the insular cortex is:
“… highly involved in integrating somatosensory, autonomic and cognitive-affective information to guide behaviour. Thus, it acts as a central hub for processing relevant information related to the state of the body as well as cognitive and mood states. Despite these crucial functions, the insula has been largely overlooked as a potential key region in contributing to non-motor symptoms of Parkinson’s disease. The insula is affected in Parkinson’s disease by alpha-synuclein deposition, disruptions in normal neurotransmitter function, alterations in connectivity as well as metabolic and structural changes. Although research focusing on the role of the insula in Parkinson’s disease is scarce, there is evidence from neuroimaging studies linking the insula to cognitive decline, behavioural abnormalities and somatosensory disturbances.”
A more recent article in the journal Neurology provides another overview of the roles served by the insular cortex:
“The posterior (granular) insula receives inputs from pain, temperature, visceral, vestibular, and other sensory pathways; this multimodal sensory representation is further elaborated in the midinsular (dysgranular) cortex and then conveyed to the anterior (agranular) insula, which further processes this information and interacts with areas involved in cognitive and emotional control. The insula thus provides an interface between bodily sensation and emotion and may have a key role in perceptual awareness, social behavior, and decision making.”
In other words, the insular cortex is involved in states of consciousness, particularly switching between thinking, planning, and emotions. It plays a role in autopilot function, internal body perception such as pain and homeostasis, and emotion management in goal-directed behavior. It serves as a buffer between incoming sensory input and higher cortical functions aimed at goal attainment.
Researchers hypothesize that impairment in insular cortex functioning correlates with a progression in Parkinson’s disease.
Clinical presentation of patients who have damage to the insular cortex can include the following:
- Difficulty moderating emotions, including anxiety and depression
- Hypersensitivity to sound
- Breakdowns in autopilot functioning
- Problems maintaining homeostasis, such as temperature regulation and sweating
- Chronic pain
These are all symptoms present in my clinical portrait.
Science supports the idea that there is a second dopamine production area involved with Parkinson’s disease: the insular cortex. If you are looking for more information, neuroscientist Nadine Gogolla published in the journal Current Biology a nice overview of the insular cortex, including its biology and functions.
What does this mean to you or me or any patient who experiences these symptoms but does not demonstrate profound tremors or shaking? To be fair, the science of Parkinson’s disease is not exact. It is being researched and studied, and for every posited determination of cause, more questions arise. There is so much we don’t know.
I am a strong advocate of science. I was trained in two different domains to ask questions and investigate occurrences, causes, and effects in a systematic manner.
As patients, we seek professional opinions to understand our diseases and to seek treatment for symptoms. Ultimately, we are responsible for our own health. As we cannot assume innocence of knowing what impacts our health adversely, we must be responsible for what we can do better.
Note: Parkinson’s News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Parkinson’s News Today or its parent company, BioNews, and are intended to spark discussion about issues pertaining to Parkinson’s disease.