Figure showing the insular cortex (circled) in a coronal section indicated by the blue line in the inset, Modified from Original Image by John Beal PhD, Dep’t. of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center Shreveport, CC-BY
In this series of posts I am describing the process of building a model of the Insular Cortex. I thought the most straightforward way to develop such a model is to begin with a narrative. This informs a top-down approach where an overview is gained before the details are filled out. Although this model is specific to the Insular Cortex, the approach can be applied to other brain regions. I have described this as an open model – one which uses the principles of the web which is collaboration. There have been numerous contributions which I can delineate more clearly once the basic structure starts to take shape.
In the series so far there have been four parts each focusing on a different narrative.
Part 1 – The intensity of emotional experience is dependent on two factors
1. The GABA receptor density in the Anterior Insular Cortex
2. The sensory input to the Anterior Insular Cortex
Furthermore a reduction in emotional experience can lead to difficulties in relationships with others.
Part 2 – Looking at Craig’s work there is a brief look at Craig’s idea that the Von Economo Neurons which are highly interconnected to other widely dispersed neurons, form the basis for conscious experience.
Part 3 – Looking again at Craig’s model of the Insular Cortex he proposes that
1. The Anterior Cingulate Cortex and the Anterior Insular Cortex are tightly linked
2. The Anterior Insular Cortex acts as the Limbic Sensory Cortex
3. The Anterior Cingulate Cortex acts as the Limbic Motor Cortex
4. That emotions are associated with actions
5. The Anterior Cingulate Cortex is the locus for our sense of agency associated with an emotion
6. The Anterior Insular Cortex is the locus for our experience of an emotion
Part 4 – Looking again at Craig’s model, he argues that the Anterior Insular Cortex is the locus for human awareness or consciousness as it is activated in numerous functional Magnetic Resonance Imaging studies.
I argue that this narrative is countered by critiques of functional Magnetic Resonance Imaging methodology where there are alternative explanations for apparent Anterior Insular Cortex activity. Instead consciousness exists as a modular phenomenon which is mapped onto distributed brain regions.
Part 5 – Looking again at Craig’s model, he looks at an evolutionary explanation of the Insular Cortex in which
1. The Hippocampus and Amgygdala received olfactory inputs in early mammals
2. The Anterior Cingulate Cortex initiated actions in response to the processing of these stimuli
3. Mammals organised group behaviours in response to olfactory stimuli
4. They started to respond to autonomic activity which was processed by the Insular Cortex
5. The Insular Cortex expanded and utilised the Anterior Cingulate Cortex to effect motor responses to the autonomic input
There are many other aspects of Craig’s model to examine and a wider body of research literature and comments to incorporate into the model.
Insular Cortex Resources on this Site
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