<p>The <a href="https://en.wikipedia.org/wiki/Default_mode_network" rel="nofollow noreferrer">default mode network (DMN)</a> is a collection of brain structures identified in human functional neuroimaging.</p>
<p>Specifically, a type of neuroimaging called <a href="https://en.wikipedia.org/wiki/Blood-oxygen-level-dependent_imaging" rel="nofollow noreferrer">BOLD</a> indirectly measures local metabolism in the brain; the assumption is that areas with a strong BOLD signal are active.</p>
<p>It's typical to use <a href="https://en.wikipedia.org/wiki/Pearson_correlation_coefficient" rel="nofollow noreferrer">Pearson correlations</a> of the BOLD signal over time between different brain regions to measure what is called <a href="https://psychology.stackexchange.com/questions/24705/functional-vs-synaptic-connectivity/24711#24711">&quot;functional connectivity&quot;</a>: regions are said to be functionally connected if they have high metabolism at the same time, and low metabolism at the same time. In other words, if their BOLD signals are positively correlated, they are said to be functionally connected.</p>
<p>The DMN is a particular collection of brain regions found to have high correlations among each other = high functional connectivity <em>at rest</em>, when people sit in the scanner doing nothing else. This is an <em>observation</em> that is very consistent and reliable in &quot;normal&quot; participants in fMRI studies.</p>
<p>Given this reliable signal, scientists have sought to connect the DMN to psychiatric disorders. If someone says &quot;DMN hypoconnectivity in (condition A)&quot;, what they typically mean is &quot;we measured Pearson correlations of BOLD signals in brain regions that people know are usually highly connected at rest; we found the strength of those connections was weaker in (condition A) than in participants without that condition&quot;. Hyperconnectivity would mean the opposite: higher correlations in (condition B) than in a control population.</p>
<p>Those are both examples of <em>intraconnectivity</em> in terms of the DMN: connections within=intra that network. It's possible to break the rest of the brain into other networks, or just one broad &quot;not-DMN&quot; network. If a paper talks about &quot;interconnectivity&quot; with the DMN, they are talking about the relationship between parts of the brain that are in the DMN and other parts of the brain.</p>
<p>Everything that comes after that is pure speculation, or needs to be supported by something else. In one of the papers you link, the authors write:</p>
<blockquote>
<p>Constant overengagement of the default network could lead to an exaggerated focus on one's own thoughts and feelings as well as an ambiguous integration between one's own thoughts and feelings with events in the environment. Thus, neutral events would seem to be imbued with exaggerated self-relevance, and the boundary between the internal world of reflection and feeling and the external world of perception and action would be weakened. Indeed, many symptoms of schizophrenia involve an exaggerated sense of self-relevance in the world, such as paranoid ideation that individuals and groups are conspiring against the patient, and a blurring of internal reflection and external perception, such as hallucinations.</p>
</blockquote>
<p>That's all just the authors' speculation (which is perfectly appropriate for a discussion section; that's what they're doing, discussing the results). They are interpreting the result they found (DMN hyperconnectivity) in terms of other things they already know about the psychiatric condition they are interested in.</p>

CC BY-SA 4.0
2022-03-18T23:29:02.027Z
This is incredibly helpful Bryan. Thank you very much for the prompt and succinct yet not reductive answer. I will follow up with the links you have provided and do further reading into the subject matter. Again, thank you very much.
TheMatureNeuro
CC BY-SA 4.0
2022-03-18T23:13:19.863Z
2022-03-18T23:13:19.863Z
Bryan Krause
<p>I have been reading into DMN and its relationship to psychopathology. However, in some papers I have noticed terminology that mentioned hypo-,hyper-,inter-, and intra<em>connectivity</em>. While I understand what the prefixes mean, I fail to understand the actual functional relationship to the DMN. Could someone please provide me with the definition for each and an example which includes each of the terms?</p>
<p>I link some of the articles which mention hyperconnectivity in Schizophrenia and others.</p>
<p>Edit:</p>
<p>Upon recommendation from one of the comments, I will redefine the specific aspect of the question which I struggle with. What is hyperconnectivity (and the other 3 terms) in terms of DMN? What does the hyperconnectivity (to choose as an example from the selection) relate to?</p>
<p>A second question is, what does hypo-, and hyperconnectivity mean in terms of the relationship between ASD and DMN?</p>
<p><a href="https://www.ncbi.nlm.nih.gov/sites/ppmc/articles/PMC2633557/" rel="nofollow noreferrer">https://www.ncbi.nlm.nih.gov/sites/ppmc/articles/PMC2633557/</a></p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8112713/" rel="nofollow noreferrer">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8112713/</a></p>

CC BY-SA 4.0
2022-03-18T22:29:05.283Z
Can you explain a bit more what exactly it is that you're not understanding? Possibly a specific quote from one of the papers would help. Is it the meaning of *connectivity*? Why DMN is relevant to a mental illness like schizophrenia? Is it the meaning of prefixes like hypo/hyper/inter/intra?
Bryan Krause
CC BY-SA 4.0
2022-03-18T22:54:29.603Z
Hi @BryanKrause thank you for the recommendation. I have now inserted an edit to specify what I struggle with.
TheMatureNeuro
<cognitive-psychology><neuroscience><abnormal-psychology><cognitive-modeling><clinical-psychology>
Default Mode Network and: hyper-connectivity, hypo-connectivity, interconnectivity and intraconnectivity
TheMatureNeuro
# Default Mode Network and: hyper-connectivity, hypo-connectivity, interconnectivity and intraconnectivity

(Asked by: username_0 on 2022-03-18)

I have been reading into DMN and its relationship to psychopathology. However, in some papers I have noticed terminology that mentioned hypo-,hyper-,inter-, and intra*connectivity*. While I understand what the prefixes mean, I fail to understand the actual functional relationship to the DMN. Could someone please provide me with the definition for each and an example which includes each of the terms?

I link some of the articles which mention hyperconnectivity in Schizophrenia and others.

Edit:

Upon recommendation from one of the comments, I will redefine the specific aspect of the question which I struggle with. What is hyperconnectivity (and the other 3 terms) in terms of DMN? What does the hyperconnectivity (to choose as an example from the selection) relate to?

A second question is, what does hypo-, and hyperconnectivity mean in terms of the relationship between ASD and DMN?

<https://www.ncbi.nlm.nih.gov/sites/ppmc/articles/PMC2633557/>

<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8112713/>

**Tags:** cognitive-psychology, neuroscience, abnormal-psychology, cognitive-modeling, clinical-psychology

> **Comments:**
> **username_1**: Can you explain a bit more what exactly it is that you're not understanding? Possibly a specific quote from one of the papers would help. Is it the meaning of *connectivity*? Why DMN is relevant to a mental illness like schizophrenia? Is it the meaning of prefixes like hypo/hyper/inter/intra?  
> **username_0**: Hi @BryanKrause thank you for the recommendation. I have now inserted an edit to specify what I struggle with.  

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## 1 answers

### Answer by username_1 on 2022-03-18. Score: 3 | Accepted answer

The [default mode network (DMN)](https://en.wikipedia.org/wiki/Default_mode_network) is a collection of brain structures identified in human functional neuroimaging.

Specifically, a type of neuroimaging called [BOLD](https://en.wikipedia.org/wiki/Blood-oxygen-level-dependent_imaging) indirectly measures local metabolism in the brain; the assumption is that areas with a strong BOLD signal are active.

It's typical to use [Pearson correlations](https://en.wikipedia.org/wiki/Pearson_correlation_coefficient) of the BOLD signal over time between different brain regions to measure what is called ["functional connectivity"](https://psychology.stackexchange.com/questions/24705/functional-vs-synaptic-connectivity/24711#24711): regions are said to be functionally connected if they have high metabolism at the same time, and low metabolism at the same time. In other words, if their BOLD signals are positively correlated, they are said to be functionally connected.

The DMN is a particular collection of brain regions found to have high correlations among each other = high functional connectivity *at rest*, when people sit in the scanner doing nothing else. This is an *observation* that is very consistent and reliable in "normal" participants in fMRI studies.

Given this reliable signal, scientists have sought to connect the DMN to psychiatric disorders. If someone says "DMN hypoconnectivity in (condition A)", what they typically mean is "we measured Pearson correlations of BOLD signals in brain regions that people know are usually highly connected at rest; we found the strength of those connections was weaker in (condition A) than in participants without that condition". Hyperconnectivity would mean the opposite: higher correlations in (condition B) than in a control population.

Those are both examples of *intraconnectivity* in terms of the DMN: connections within=intra that network. It's possible to break the rest of the brain into other networks, or just one broad "not-DMN" network. If a paper talks about "interconnectivity" with the DMN, they are talking about the relationship between parts of the brain that are in the DMN and other parts of the brain.

Everything that comes after that is pure speculation, or needs to be supported by something else. In one of the papers you link, the authors write:

> Constant overengagement of the default network could lead to an exaggerated focus on one's own thoughts and feelings as well as an ambiguous integration between one's own thoughts and feelings with events in the environment. Thus, neutral events would seem to be imbued with exaggerated self-relevance, and the boundary between the internal world of reflection and feeling and the external world of perception and action would be weakened. Indeed, many symptoms of schizophrenia involve an exaggerated sense of self-relevance in the world, such as paranoid ideation that individuals and groups are conspiring against the patient, and a blurring of internal reflection and external perception, such as hallucinations.

That's all just the authors' speculation (which is perfectly appropriate for a discussion section; that's what they're doing, discussing the results). They are interpreting the result they found (DMN hyperconnectivity) in terms of other things they already know about the psychiatric condition they are interested in.

> **Comments:**
> **username_0**: This is incredibly helpful Bryan. Thank you very much for the prompt and succinct yet not reductive answer. I will follow up with the links you have provided and do further reading into the subject matter. Again, thank you very much.  

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