Large-Scale Brain Networks and Psychopathology: A Unifying Triple Network Model -Menon

What is small-world architecture? Is it present in the brain? How about social networks?

1. A small-world architecture = graph in which most nodes are NOT neighbors of one another, but the neighbors of any given node are likely to be neighbors of each other and most nodes can be reached from every other node by a small number of hops to steps. It is a dense local clustering of connections between neighboring nodes and a short path length between nodes. Small-world networks are cost-effective wiring without losing any data. 2. Yes, this is present in the brain of healthy adults, and deviance from them is a sign of significant global deficiency in brain organization. 3. Yes, strangers are connected to other strangers by other people around them

What measures can one use to describe a dysfunctional brain organization? The author mentions five of them. Don't memorize the list, but be able to recognize and explain each of the measures

1. Abnormal small-world architecture → sign of significant global deficits in brain organization Measures: path length between nodes, clustering coefficient, and cumulative metric sigma (ratio of normalized clustering coefficient to the characteristic path length, a measure of small-world organization) 2. Dysfunctional subsystems → examine functional organization in key subdivisions of the brain. Examining the global connectivity of regions with known structural pathology can help identify disrupted subnetworks and cognitive systems differently impacted by each disorder 3. Compensatory subsystems → Regional and subnetwork analysis can provide evidence for compensatory subsystems 4. Identification of dysfunctional hubs → When one hub has abnormal connections. Ex: PCC hub usually has processing disruptions in patients with AD (Alzheimer's disease) 5. Disease identification, onset, and progression → network metrics can be used as biomarkers to distinguish between disease stages

What are the three core neurocognitive networks (according to Dr. Vinod Menon)? What brain structures are they anchored in?

1. Central executive network (CEN) = frontoparietal system anchored in dlPFC and the lateral PPC 2. Default Mode Network (DMN) = typically deactivated during most stimulus-driven cognitive tasks. Anchored in the PCC and mPFC, with prominent nodes in the medial temporal lobe (MTL) and angular gyrus 3. Salience network (SN) = a cingulate-frontal operculum system anchored in the dorsal anterior cingulate cortex (dACC) and frontoinsular cortex (FIC) Is involved in detecting, integrating, and filtering relevant interoceptive, autonomic and emotional information

What is unique about the insula from the network perspective? Where is it located?

1. The insula is unique in that it's situated at the interface of the cognitive, homeostatic, and affective systems of the human brain, providing a link between stimulus-driven processing and brain regions involved in monitoring the internal milieu and interoceptive awareness of physiological changes in the body. Connects two nodes. 2. The two nodes are the amygdala and nucleus acumens

What are the nodes and edges in a brain network? (In graph theory, nodes can also be called vertices.)

A node (vertices) = brain regions An edge = functional interactions between two brain regions Dysfunctional nodes or edges result in aberrant signaling which can then propagate to the whole network or subnetworks across the brain

What is the recent paradigm shift in the study of brain dysfunction? (Don't itemize; extract the main idea.)

Focuses on understanding how disturbances in distributed brain areas operating within large-scale networks contribute to cognitive and affective dysfunction Changed to believing intrinsic function is essential to brain function

What is graph theory?

Graph theory = the study of graphs, which are mathematical structures used to model pairwise relations between objects and are data structures that have nodes and edges that link the nodes It can be used to analyze any large-scale network.

Which of the three networks may act as a switch for the other two?

SN The crucial role of the SN for initiating network switching leading the engagement of the CEN and disengagement of the DMN

From the network perspective, what is the fundamental difference between the anterior cingulate cortex (ACC) and the posterior cingulate cortex (PCC), and between the dorsolateral PFC (dlPFC) and the ventromedial PFC (vmPFC)?

SN Key nodes = AI and ACC CEN Key nodes= DlPFC and PPC DMN Key nodes = vmPFC and PCC Basically, the ACC is in the SN and the PCC is in the DMN. The dlPFC is in the CEN, the vmPPFC is in the DMN. They are in different systems

Which of the three networks is involved in the processing of pain and the empathy for pain?

The SN (salience network) → both AI (anterior insula) and dAAC (dorsal anterior cingulate cortex)

Which of the three networks is closely associated with the amygdala, the substantia nigra, and the ventral tegmental area (VTA)?

The SN (salience network); They are used for emotions and rewards

What is a brain hub?

a node with a number of link that greatly exceed the average