A Diversion into the Limbic System Building a Model of the Insular Cortex – Part 16

A Model of the Insular Cortex

In this series we are looking to build a model of the Insular Cortex in terms of emotional regulation. Along the way we have seen that a number of other brain circuits are involved in emotions as reflected in the diagram above. In this post I have taken a diversion into the Limbic System to better contextualise the role of the Insular Cortex in emotions.

We can ask the question what is the role of the Limbic System in emotions that would distinguish it from the Insular Cortex? In order to begin to answer this question we would need to better understand the Limbic System itself. In this post I’m looking at a review article about the Hippocampus, a key part of the Limbic System. The paper is titled ‘Decoding information in the Human Hippocampus: A User’s Guide‘ by Chadwick, Bonnici and Maguire.

The authors look at a neat statistical analytical technique known as multi-voxel pattern analysis (MPVA) which is increasingly being used in fMRI analysis. In fMRI analysis, the brain is divided up into voxels which are volume units. This facilitates analysis of the activity detected by the scanner. Much of the analysis has involved region of interest analysis where activity in a region of the brain is analysed in relation to the experimental variables of interest.

The problem inherent in this technique is that it makes an assumption about brain activity which then constrains the subsequent analysis. The analysis assumes that the region is involved in the activity rather than discrete areas within multiple regions or even discrete areas within brain regions. However if activity occurs within discrete networks within a single region, then a region of interest analysis will overlook this activity which is lost in the averaged data.

MVPA divides voxels into groups and assesses activity against the experimental variables of interest. In a simple example it would be state A or B. There are multiple groups which allow multiple tests of the data. The analysis uses the number of experimental states to facilitate an assessment of the accuracy of the analysis in predicting activity-state correlates.

The paper then summarises some of the research that has been done using this approach and the results are very interesting. Check the paper for more details (including a few missing steps based on frequency maps to get to some of the results below) but what some of the research is suggesting is that

1. The Hippocampus works by separating out patterns that are presented to it and turning them into unique events. A crude example would be separating out apples and oranges that are presented in sequence. Components of both apples and oranges such as red, orange, peel and shape would be utilised to discriminate one from the other. This has been suggested from previous research but some of the experimental evidence here is quite neat.

The Hippocampus

2. The Hippocampus stores information about scenes according to spatial location distributed amongst different memories. Based on research by Hassabis and colleagues there was also a suggestion that the Posterior Parahippocampal Cortex played a role in storing different aspects of environments in a way which was possibly complementary to the Hippocampus

The Parahippocampal Gyrus

3. Episodic memories were likely to be stored in the Hippocampus, Parahippocampal Cortex and Entorhinal Cortex with Hippocampal activity appearing to be better correlated with these memories.

4. That the Hippocampus may form memories based on principles utilised in neural networks. The story here however is less straightforward. Rather than simple attractor networks it looks as though the Hippocampus creates/stores simple networks and then generates modified networks based on novel but slight different patterns. To me this sounded a bit like the process of induction.

5. Activity in the Hippocampus was correlated with higher level decision making based on classifying patterns.

Perhaps the fifth point is one of the most important ones as it suggests that the Hippocampus as part of the Limbic System could be playing a central role in decision making on the basis of received sensory information/perception. This easily lends itself to a discussion of the emotions.

Related Resources on this Site

Developing a Model of the Insular Cortex and Emotional Regulation: Part 1

Building a Model of the Insular Cortex – Part 2: Reviewing a Model by Craig – Part 1

Building a Model of the Insular Cortex – Part 3: Reviewing a Model by Craig – Part 2

Building a Model of the Insular Cortex – Part 4: Reviewing a Model by Craig – Part 3

Building a Model of the Insular Cortex – Part 5: The Evolution of the Insular Cortex

Building a Model of the Insular Cortex – Part 6: A Recap

Building a Model of the Insular Cortex – Part 7: The James-Lange Theory

Building a Model of the Insular Cortex – Part 8: The Cannon-Bard Thalamic Theory of Emotions

Building a Model of the Insular Cortex – Part 9: Charles Darwin on the Expression of the Emotions

Building a Model of the Insular Cortex – Part 10: The Limbic System

Building a Model of the Insular Cortex – Part 11: A Second Recap

Building a Model of the Insular Cortex – Part 12: GABA receptors and Emotions

Building a Model of the Insular Cortex – Part 13: GABA receptors and Nematode Worms

Building a Model of the Insular Cortex – Part 14: Are GABA Receptors Related to Anxiety in Humans Because Worms Wriggle?

Building a Model of the Insular Cortex – Part 15: Another Recap

What does the Insular Cortex Do Again?

Insular Cortex Infarction in Acute Middle Cerebral Artery Territory Stroke

The Insular Cortex and Neuropsychiatric Disorders

The Relationship of Blood Pressure to Subcortical Lesions

Pathobiology of Visceral Pain

Interoception and the Insular Cortex

A Case of Neurogenic T-Wave Inversion

Video Presentations on a Model of the Insular Cortex

MR Visualisations of the Insula

The Subjective Experience of Pain

How Do You Feel? Interoception: The Sense of the Physiological Condition of the Body

How Do You Feel – Now? The Anterior Insula and Human Awareness

Role of the Insular Cortex in the Modulation of Pain

The Insular Cortex and Frontotemporal Dementia

A Case of Infarct Connecting the Insular Cortex and the Heart

The Insular Cortex: Part of the Brain that Connects Smell and Taste?

Stuttered Swallowing and the Insular Cortex

YouTubing the Insular Cortex (Brodmann Areas 13, 14 and 52)

New Version of Video on Insular Cortex Uploaded

Contributors to the Model (links are to the posts in which contributions were made – these links may contain further links directly to the contributors)

Ann Nonimous

The Neurocritic


Index: There are indices for the TAWOP site here and here Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.


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