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Attention and Insight
Published in Lisa Heschong, Visual Delight in Architecture, 2021
First the researchers noticed that for any given type of task, brain activity was rarely limited to one precise location; rather, many areas of the brain would all light up simultaneously. Therefore, rather than looking for particular locations, they started looking for patterns and how the patterns shifted with different types of tasks. And then, secondly, they began to recognize one pattern of brain activity that occurred frequently and repeatedly during all the tests, universally across all types of task assignments. This brain activation pattern was named the default mode network (DMN), since it was initially hypothesized that it was some kind of resting or idle mode that the brain returned to in-between working on the task assignment. However, that hypothesis was put to rest, so to speak, once researchers discovered that the default mode network used at least as much, if not more, energy than any of the task-specific activity patterns.
Brain Imaging Data
Published in Atsushi Kawaguchi, Multivariate Analysis for Neuroimaging Data, 2021
Figure 2.2 is called task-related research, which is conducted with various stimuli and tasks, and conversely, resting state research, which is conducted in a resting state without any stimuli. In recent years, network analysis has been widely used to evaluate the functional connectivity between resting sites. Please refer to Chapter 5 for the analysis. The medial prefrontal cortex and the anterior cuneiform and posterior cingulate gyrus are a network of brain regions called the default mode network (DMN), and they are more active when the subject is awake but not doing anything (Raichle et al., 2001). This neural activity consumes 60–80% of the energy in the brain. However, on the other hand, the energy expenditure of neural activity is only 0.5–1.0% in the brain while performing some kind of task. The DMN has been studied in various psychiatric disorders as it is believed to be involved in internal thought processes and the control of external stimuli (Joo et al., 2016; Liu et al., 2017). In addition to the DMN, several other networks showing activity at rest have been identified and resting-state fMRI is thought to contain a lot of information about individual brain function. Tavor et al. (2016) showed that an individual’s functional connectivity pattern of resting fMRI can predict the pattern of fMRI activity while performing a task.
Mapping the Injured Brain
Published in Yu Chen, Babak Kateb, Neurophotonics and Brain Mapping, 2017
Chandler Sours, Jiachen Zhuo, Rao P. Gullapalli
An additional area of active research concerns the deactivation of the default mode network (DMN), a group of regions that are known to display reduced activation during task-related activities while demonstrating increased activity during rest conditions (Greicius et al., 2003; Raichle et al., 2001). It has been proposed that the failure to successfully deactivate the DMN during goal-directed behavior results in an interference in cognitive processing due to the intrusion of internal thoughts. This failure to deactivate these regions manifests itself as a lapse in attention and reduced behavioral performance (Sonuga-Barke and Castellanos, 2007). Further research suggests the balance between activation of the TPN and deactivation of the DMN is associated with reduced cognitive performance in healthy controls (Sala-Llonch et al., 2012; Weissman et al., 2006) and is disrupted in aging (Prakash et al., 2012; Sambataro et al., 2010), sleep deprivation (De Havas et al., 2012), schizophrenia (Woodward et al., 2011), and ADHD (Castellanos et al., 2009). Most importantly, groups have reported reduced deactivation of DMN regions during task execution in severe or mixed TBI populations (Bonnelle et al., 2011; Sharp et al., 2011), as well as mTBI patients in the subacute stage (Mayer et al., 2012).
Are episodic memories special? On the sameness of remembered and imagined event simulation
Published in Journal of the Royal Society of New Zealand, 2018
The brain’s DMN includes the medial temporal lobes, medial aspects of the frontal and parietal cortices, inferior lateral parietal cortex and lateral temporal cortex. Although this same set of brain regions has been described previously as the autobiographical retrieval network (Maguire 2001), the recollection network (Rugg & Vilberg 2013) and the common core network (i.e. common to both remembering past events and imagining future events; Schacter & Addis 2007), it is now widely known as the DMN because of its ubiquitous activity when individuals are not engaged in a cognitive task requiring external attention (e.g. reading words). It has become increasingly apparent, however, that DMN activity is not really about the absence of a cognitive task, but rather the mind wandering to the past and the future when not otherwise occupied (Spreng 2012). In other words, our simulation system is engaged when we are in our default mode and mind-wandering, and this network can be modulated according to whether the cognitive task at hand requires simulation (e.g. episodic memory tasks; Spreng 2012).
Discriminant subgraph learning from functional brain sensory data
Published in IISE Transactions, 2022
Lujia Wang, Todd J. Schwedt, Catherine D. Chong, Teresa Wu, Jing Li
Interpretations: From Figure 4, we can see that the partial correlation matrix of each class shows strong positive correlations between the left and right hemisphere for the same ROI. This phenomenon has been previously reported for both healthy and diseased brains (Chong et al., 2019). Some of these correlations have no significant difference between the EM and control classes, whereas some others do. A significant difference is also observed between other ROIs. Furthermore, it is interesting that several ROIs in the subgraph found by DSL are part of well-known functional networks or anatomical regions. For example, the left and right anterior cingulate cortex (3, 4), the left and right posterior cingulate cortex (9, 10) and the bilateral ventromedial are all regions involved in the Default Mode Network (DMN). This functional network shows synchronous activity when a person is at rest and not actively partaking in an activity. The DMN is involved in self-reflection and mind-wandering (Raichle et al., 2001) and results of several imaging studies have shown abnormal functional connectivity amongst regions of the DMN in patients with migraine (Yu et al., 2012; Tessitore et al., 2013; Faragó et al., 2017). Other ROIs that are important in our model include regions of the limbic system such as the left and right amygdala (27, 28), the left and right thalamus (11, 12). In accordance with our results, Hadjikhani et al. (2013) found stronger functional connectivity between the thalamus and the amygdala in those who experience migraines relative to patients with other chronic pain disorders, indicating that aberrant functional connectivity between these regions might be unique to migraine patients.