NeuroImage
June 13, 2008
Peter Fransson, Guillaume Marrelec
1,236 citations
Functional connectivity within the default mode network was assessed during rest and a continuous working memory task using partial correlation analysis. The precuneus/posterior cingulate region showed strong interactions with the rest of the network, while the left and right medial temporal lobes interacted strongly with each other but weakly with other regions. Strong interactions were also found between the precuneus/posterior cingulate cortex and the left inferior parietal lobe, and between dorsal and ventral sections of the medial prefrontal cortex. These findings support a pivotal role for the precuneus/posterior cingulate cortex in the default mode network.
NeuroImage
May 24, 2014
Nia Goulden, Aygul Khusnulina, Nicholas J. Davis et al.
828 citations
The salience network drives switching between the default mode network (DMN), active when the brain is not focused on a task, and the central executive network (CEN), active during attention-demanding tasks. Combining dynamic causal modelling with independent component analysis, this work tested network switching in resting-state data from two independent datasets. The results confirm that the salience network is responsible for this switching and demonstrate the repeatability of the novel technique.
NeuroImage
February 15, 2016
Christopher G. Davey, Jesus Pujol, Ben J. Harrison
576 citations
The brain's default mode network (DMN) is linked to self-referential thought during rest, but it also serves other functions, and self-reference involves regions outside the DMN. In 88 participants, self-referential and resting-state brain activity were compared to identify DMN areas common to both conditions that also show specialization for self-reference. The 'core-self' DMN regions—medial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobule—were analyzed with dynamic causal modeling. The optimal model indicated that self-related processes are driven by posterior cingulate activity and moderated by the medial prefrontal cortex. This confirms these regions' importance for self-reference and clarifies their specialized roles.
NeuroImage
April 11, 2010
Kaustubh Supekar, Lucina Q. Uddin, Katherine E. Prater et al.
548 citations
The default-mode network (DMN) undergoes significant developmental changes in functional and structural connectivity from childhood to adulthood, but these changes are not uniform across all DMN nodes. The connection between the posterior cingulate cortex (PCC) and medial prefrontal cortex (mPFC) along the cingulum bundle is the most immature link in children. Structural connectivity between PCC and left medial temporal lobe is weak or non-existent in children, yet functional connectivity does not differ from adults. Gray matter volume differences and macrostructural and microstructural differences in the dorsal cingulum bundle also appear. Maturation of PCC-mPFC structural connectivity likely supports self-related and social-cognitive functions emerging during adolescence.
NeuroImage
May 15, 2009
Catie Chang, Gary H. Glover
510 citations
Negative correlations between the default-mode network and the task-positive network are present in most individual subjects both with and without physiological noise correction. Physiological noise correction increased the spatial extent and magnitude of these negative correlations, yielding negative correlations within task-positive regions at the group level (p<0.05, uncorrected; no regions at the group level were significant at FDR=0.05). Correction also caused region-specific decreases in positive correlations within the default-mode network, reducing apparent false positives. The low-frequency respiratory volume and cardiac rate regressors used in the correction algorithm shared significant but not total variance with the global signal, offering a model-based alternative to global signal removal.
NeuroImage
June 25, 2014
Aaron Kucyi, Karen D. Davis
381 citations
Daydreaming is linked to how brain networks fluctuate over time, not just their average connectivity. In healthy adults, those who daydreamed more showed less stable connectivity between the posterior cingulate cortex and a part of the default mode network involved in future thinking. However, greater moment-to-moment variability in that same network's connectivity predicted more mind-wandering during a sensory task. The findings suggest that dynamic, rather than static, brain network activity reflects the conscious experience of daydreaming.
NeuroImage
October 4, 2013
Andreas Horn, Dirk Ostwald, Marco Reisert et al.
375 citations
Voxels in the default mode network (DMN) show the highest agreement between structural and functional connectivity in the human brain. Using fMRI and DTI data, structural connectivity was measured with probabilistic and global fiber-tracking, while functional connectivity used full and partial correlations of voxel timecourses. Bilateral precuneal and inferior parietal regions were identified by all methods; global tracking additionally revealed medial prefrontal cortices and early visual areas. Full and partial correlations yielded no significant differences. The DMN appears to use the most direct structural connections, suggesting the brain's anatomy shapes its functional repertoire.
NeuroImage
August 19, 2011
Jack A. De Havas, Sarayu Parimal, Chun Siong Soon et al.
371 citations
Sleep deprivation reduces functional connectivity within the brain's Default Mode Network and weakens its anti-correlation with the task-positive network. These effects occur both at rest and during a visual attention task, indicating a robust alteration in intrinsic brain network organization. The study involved 26 healthy participants scanned after a normal night of sleep and after about 24 hours of total sleep deprivation.
NeuroImage
January 11, 2019
Michele Colombo, Martino Napolitani, Melanie Boly et al.
359 citations
During anesthesia, people may still be conscious even though they do not respond. A marker of consciousness based on the decay rate of the power spectral density (PSD) of resting EEG—measured by the spectral exponent β—was tested in healthy participants under xenon, propofol, or ketamine anesthesia (n=5 per group). Delayed reports indicated whether consciousness was present or absent. Xenon and propofol, which abolish consciousness, caused a steeper PSD decay (more negative β) compared to wakefulness. Ketamine, which preserves consciousness, showed a PSD decay similar to wakefulness overall but a flattening in high frequencies (20–40 Hz). The spectral exponent correlated strongly with the Perturbational Complexity Index (PCI), supporting its use as a marker of consciousness.
NeuroImage
December 17, 2009
Zhigang Qi, Xia Wu, Zhiqun Wang et al.
328 citations
People with amnestic mild cognitive impairment (aMCI), a transitional stage between healthy aging and Alzheimer's disease, show altered brain activity in the default mode network (DMN) compared to healthy older adults. Using resting-state fMRI, 14 healthy elderly participants showed increased activity in DMN regions including the bilateral precuneus/posterior cingulate cortex, right inferior parietal lobule, and left fusiform gyrus, with a trend toward increased right medial temporal lobe activity. The 14 aMCI patients showed increased activity in the left prefrontal cortex, inferior parietal lobule, and middle temporal gyrus, which may reflect compensatory processes. These abnormal DMN activity patterns could serve as an imaging biomarker for diagnosing and monitoring aMCI.
NeuroImage
January 15, 2009
K. Jann, T. Dierks, C. Boesch et al.
290 citations
Synchronous oscillations in the brain, particularly alpha-band activity observed in EEG, are linked to resting state networks (RSNs) seen in fMRI BOLD signals. This study reports evidence that global EEG synchronization in the alpha frequency band correlates with BOLD activity in brain areas involved in specific RSNs, such as the default mode network. The results confirm that specific RSNs are organized by long-range synchronization in the alpha band. Overlap was found between areas where BOLD correlates of global EEG synchronization and associated RSNs are located, suggesting that the spatio-temporal organization of EEG rhythms, not just spectral dynamics, is important for understanding brain network coordination.
NeuroImage
January 12, 2018
Charlotte Murphy, Elizabeth Jefferies, Shirley-Ann Rueschemeyer et al.
288 citations
The default mode network supports cognition independent of immediate environment and higher-order conceptual representations. A novel paradigm manipulated perceptual information availability and representational complexity during decision-making. Brain regions including left and right angular gyri and left middle temporal gyrus responded when cognition combined stimulus independence with multi-modal information. These default mode network sites showed stronger response to demanding memory judgments than easier perceptual tasks, contradicting the view they support automatic cognition. These regions were at the extreme end of a macroscale gradient from sensorimotor to transmodal cortex, suggesting functional distance from sensory input enables conceptually rich cognitive states in absence of input.
NeuroImage
August 1, 2019
Lukasz Smigielski, Milan Scheidegger, Michael Kometer et al.
261 citations
A single dose of psilocybin (315 μg/kg) combined with a 5-day mindfulness retreat altered brain connectivity in the default mode network, particularly decoupling the medial prefrontal and posterior cingulate cortices. This decoupling correlated with the subjective experience of ego dissolution during meditation. The extent of ego dissolution and brain connectivity changes predicted improvements in psycho-social functioning four months later. The findings suggest that psilocybin-assisted meditation facilitates neurodynamic changes in self-referential networks, linking altered self-experience to lasting behavioral changes.
NeuroImage
January 17, 2008
Andrew C.N. Chen, Weijia Feng, Huixuan Zhao et al.
261 citations
In 15 right-handed healthy college females, high-density EEG recorded during 3 minutes of eyes-closed and 3 minutes of eyes-open resting states revealed distinct spatial patterns of brain activity across frequency bands. Delta (0.5-3.5 Hz) power increased and expanded over the prefrontal area from eyes-closed to eyes-open. Theta (4-7 Hz) power decreased and shifted forward over the fronto-central area. Alpha-1 (7.5-9.5 Hz), alpha-2 (10-12 Hz), and beta-1 (13-23 Hz) powers all decreased over posterior areas. High-frequency beta-2 and gamma bands showed no change. Delta and theta powers showed strong correlation between the two states. Large individual variability in alpha power was observed, especially during eyes-closed. The findings characterize a baseline electrophysiological default mode network for resting brain activity.
NeuroImage
March 19, 2016
Kwun Kei Ng, June C. Lo, Joseph K.W. Lim et al.
237 citations
In healthy older adults, functional connectivity within brain networks (executive control and default mode networks) declines over four years, indicating a loss of functional specialization with aging. Between these networks, connectivity initially increases (greater segregation) but later decreases, following a u-shaped trajectory. The rate of this later loss in segregation is linked to a decline in processing speed. These brain connectivity changes are independent of gray matter volume loss. The findings connect age-related changes in brain network function to age-related cognitive decline.
NeuroImage
September 18, 2012
Dimitrios Kapogiannis, David A. Reiter, Auriel A. Willette et al.
212 citations
The balance of excitatory and inhibitory neurotransmitters in a key brain region strongly predicts how well the brain's default mode network (DMN) communicates internally. In 20 healthy men, glutamate and GABA levels in the posteromedial cortex (a central DMN node) explained about half of the variation in the network's intrinsic functional connectivity. Glutamate correlated positively and GABA correlated negatively with DMN connectivity; the glutamate/GABA ratio also correlated positively. Age had no independent effect. No other brain network showed this relationship. The findings suggest that local neurotransmitter concentrations within a network hub can predict the functional integrity of that entire network.
NeuroImage
October 29, 2009
Stefan J. Teipel, Arun L.w. Bokde, Thomas Meindl et al.
205 citations
Resting state functional connectivity in the default mode network (DMN) of the human brain is linked to underlying white matter microstructure. Combining diffusion tensor imaging and resting state fMRI in 20 healthy elderly adults aged 56 to 83, the authors found that functional connectivity between the posterior cingulate and hippocampus was associated with white matter integrity in the cingulate bundle and related fiber tracts. A data-driven analysis confirmed a pattern of white matter tracts resembling the hypothesis-driven findings and linked to DMN connectivity. The results support the idea that DMN functional connectivity is grounded in distinct anatomical connections within cerebral white matter.
NeuroImage
September 1, 2020
Frederick S Barrett, Samuel R Krimmel, Roland R Griffiths et al.
191 citations
Psilocybin, a serotonin 2A receptor partial agonist, alters claustrum function in humans. In 15 healthy participants, psilocybin decreased the amplitude of low-frequency fluctuations and variance of BOLD signal in the left and right claustrum. It also changed functional connectivity: right claustrum connectivity with auditory and default mode networks decreased, while connectivity with the fronto-parietal task control network increased; left claustrum connectivity with the fronto-parietal task control network decreased. Subjective effects predicted these neural changes. The findings provide the first empirical evidence that 5-HT2A receptor signaling significantly modulates claustrum activity, suggesting a role for the claustrum in psilocybin's subjective and therapeutic effects.
NeuroImage
February 15, 2021
Andrea I Luppi, Robin L Carhart-Harris, Leor Roseman et al.
186 citations
LSD alters brain network dynamics non-uniformly over time, making globally segregated connectivity states more complex and weakening the link between functional and anatomical connectivity. The drug reduces functional connectivity in the anterior medial prefrontal cortex specifically during states of high segregation. Ego dissolution was predicted by increased small-world organization during a state of high global integration. These temporally-specific effects reveal a more nuanced picture of psychedelic-induced changes in brain connectivity and complexity than previously reported.
NeuroImage
July 26, 2015
D. Vatansever, D.K. Menon, A.E. Manktelow et al.
157 citations
The default mode network, long thought to be deactivated during focused tasks and to interfere with performance, may actually help fulfill cognitive demands. In a finger-tapping task with functional MRI, the network showed task-specific changes in its topography. Faster reaction times were predicted by stronger connectivity between the posterior cingulate cortex and the left superior frontal gyrus. The network's connections reconfigured dynamically during the task, maintaining efficient small-world organization while supporting higher-level parallel processing. These results suggest the default mode network does not disengage but may contribute to task-relevant processing.
NeuroImage
October 3, 2017
Federico Cavanna, Martina G. Vilas, Matías Palmucci et al.
151 citations
A review of dynamic neuroimaging research suggests that the brain's spontaneous activity fluctuates in a non-trivial, structured way, compatible with exploring a discrete repertoire of states. This supports the hypothesis of a dynamic core—a constantly evolving but transiently stable set of coordinated neurons that forms the physical substrate for each conscious experience. Studies indicate that metastability in brain dynamics may underlie this repertoire and that it can be modified during altered states of consciousness. The review proposes that linking metastability to the level of consciousness could lead to a mechanistic understanding of altered states using dynamical systems theory and statistical physics.
NeuroImage
January 18, 2017
Hannah Scheibner, Carsten Bogler, Tobias Gleich et al.
136 citations
Focused attention meditation is linked to reduced activity in the default mode network (DMN) compared to mind-wandering, regardless of whether attention is directed internally or externally. In twenty meditation-naïve adults who practiced mindfulness of sound and breathing for four days, brain scans showed that during mindful attention, regions like the medial prefrontal cortex, posterior cingulate cortex, and left temporoparietal junction were less active than during mind-wandering. Deactivation in the posterior cingulate cortex was stronger during internal attention than external attention. Refocusing after mind-wandering engaged the left inferior frontal gyrus. These findings suggest that mindful attention, not the focus of attention, drives DMN reduction.
NeuroImage
July 1, 2008
Jacob M Hooker, Youwen Xu, Wynne Schiffer et al.
106 citations
Salvinorin A, the psychoactive component of the mint plant Salvia divinorum, is a uniquely potent agonist at kappa-opioid receptors. Positron emission tomography (PET) studies in 6 adult female baboons showed extremely rapid brain uptake, reaching a peak of 3.3% of the total administered dose within 40 seconds and clearing with a half-life of 8 minutes. The compound distributed throughout the brain, with highest concentration in the cerebellum and notable concentration in the visual cortex, which may account for visual hallucinations when smoked. Naloxone did not reduce overall concentration or alter regional distribution. The rapid brain kinetics match the brief time-course of visual hallucinations, and effects may occur at less than 10 micrograms in the human brain, emphasizing its remarkable potency.
NeuroImage
July 12, 2017
Candace R. Lewis, Katrin H. Preller, Rainer Kraehenmann et al.
105 citations
Psilocybin, the active compound in psychedelic mushrooms, acts on serotonin receptors. In a placebo-controlled, double-blind study with 58 healthy participants, two oral doses of psilocybin (0.160 mg/kg and 0.215 mg/kg) were given. After adjusting for global brain perfusion, psilocybin increased relative perfusion in right frontal and temporal regions and the anterior insula, while decreasing it in left parietal and temporal cortices and left subcortical regions. However, absolute perfusion was reduced across frontal, temporal, parietal, and occipital lobes, and in bilateral amygdalae, anterior cingulate, insula, striatal regions, and hippocampi. The findings show consistency with both the hyperfrontal hypothesis and recent studies showing decreased perfusion, depending on analysis method.
NeuroImage
April 5, 2019
Duan Li, George A. Mashour
103 citations
Ketamine produces dose-dependent effects on the brain's spatiotemporal complexity. At a subanesthetic dose, ketamine elevates complexity relative to baseline, while an anesthetic dose initially causes alternating low and high complexity levels before stabilizing at a high level comparable to baseline. These findings reveal that ketamine-induced state transitions blend features of general anesthesia, normal consciousness, and altered states, advancing understanding of its pharmacological and neurophysiological properties.