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"default network"

Benjamin W Mooneyham, Michael D Mrazek, Alissa J Mrazek, Kaita L Mrazek, Dawa T Phillips, Jonathan W Schooler
During tasks that require continuous engagement, the mind alternates between mental states of focused attention and mind-wandering. Existing research has assessed the functional connectivity of intrinsic brain networks underlying the experience and training of these mental states using "static" approaches that assess connectivity across an entire task. To disentangle the functional connectivity between brain regions as the mind fluctuates between discrete brain states, we employed a dynamic functional connectivity approach that characterized brain activity using a sliding window...
October 25, 2016: Journal of Cognitive Neuroscience
Elisa C K Steinfurth, Manuela G Alius, Julia Wendt, Alfons O Hamm
The current experiments tested neural and physiological correlates of worry and rumination in comparison to thinking about neutral events. According to the avoidance model-stating that worry is a strategy to reduce intense emotions-physiological and neurobiological activity during worried thinking should not differ from activation during neutral thinking. According to the contrast avoidance model-stating that worry is a strategy to reduce abrupt shifts of emotions-activity should be increased. To test these competing models, we induced worry and neutral thinking in healthy participants using personal topics...
October 21, 2016: Psychophysiology
Antonello Baldassarre, Lenny E Ramsey, Joshua S Siegel, Gordon L Shulman, Maurizio Corbetta
PURPOSE OF REVIEW: An important challenge in neurology is identifying the neural mechanisms underlying behavioral deficits after brain injury. Here, we review recent advances in understanding the effects of focal brain lesions on brain networks and behavior. RECENT FINDINGS: Neuroimaging studies indicate that the human brain is organized in large-scale resting state networks (RSNs) defined via functional connectivity, that is the temporal correlation of spontaneous activity between different areas...
October 5, 2016: Current Opinion in Neurology
Linda Douw, Daniel G Wakeman, Naoaki Tanaka, Hesheng Liu, Steven M Stufflebeam
The brain is a dynamic, flexible network that continuously reconfigures. However, the neural underpinnings of how state-dependent variability of dynamic functional connectivity (vdFC) relates to cognitive flexibility are unclear. We therefore investigated flexible functional connectivity during resting-state and task-state functional magnetic resonance imaging (rs-fMRI and t-fMRI, resp.) and performed separate, out-of-scanner neuropsychological testing. We hypothesize that state-dependent vdFC between the frontoparietal network (FPN) and the default mode network (DMN) relates to cognitive flexibility...
September 28, 2016: Neuroscience
Kieran C R Fox, Jessica R Andrews-Hanna, Kalina Christoff
Investigation of the neural basis of self-generated thought is moving beyond a simple identification with default network activation toward a more comprehensive view recognizing the role of the frontoparietal control network and other areas. A major task ahead is to unravel the functional roles and temporal dynamics of the widely distributed brain regions recruited during self-generated thought. We argue that various other neuroscientific methods - including lesion studies, human intracranial electrophysiology, and manipulation of neurochemistry - have much to contribute to this project...
October 29, 2016: Neuroscience
Aviva Berkovich-Ohana, Michal Harel, Avital Hahamy, Amos Arieli, Rafael Malach
FMRI data described here was recorded during resting-state in Mindfulness Meditators (MM) and control participants (see "Task-induced activity and resting-state fluctuations undergo similar alterations in visual and DMN areas of long-term meditators" Berkovich-Ohana et al. (2016) [1] for details). MM participants were also scanned during meditation. Analyses focused on functional connectivity within and between the default mode network (DMN) and visual network (Vis). Here we show data demonstrating that: 1) Functional connectivity within the DMN and the Visual networks were higher in the control group than in the meditators; 2) Data show an increase for the functional connectivity between the DMN and the Visual networks in the meditators compared to controls; 3) Data demonstrate that functional connectivity both within and between networks reduces during meditation, compared to the resting-state; and 4) A significant negative correlation was found between DMN functional connectivity and meditation expertise...
September 2016: Data in Brief
Justin S Lawley, Jamie H Macdonald, Samuel J Oliver, Paul G Mullins
Hypoxia causes an increase in global cerebral blood flow, which maintains global cerebral oxygen delivery and metabolism. Yet neurological deficits are abundant under hypoxic conditions. We investigated regional cerebral microvascular responses to acute (2 h) and prolonged (10 h) poikilocapnic normobaric hypoxia. We found that 2 h of hypoxia caused an expected increase in frontal cortical grey matter perfusion, but unexpected perfusion decreases in regions of the brain normally associated with the "default mode" or "task negative" network...
August 9, 2016: Journal of Physiology
Maria Luisa Mandelli, Eduard Vilaplana, Jesse A Brown, H Isabel Hubbard, Richard J Binney, Suneth Attygalle, Miguel A Santos-Santos, Zachary A Miller, Mikhail Pakvasa, Maya L Henry, Howard J Rosen, Roland G Henry, Gil D Rabinovici, Bruce L Miller, William W Seeley, Maria Luisa Gorno-Tempini
Neurodegeneration has been hypothesized to follow predetermined large-scale networks through the trans-synaptic spread of toxic proteins from a syndrome-specific epicentre. To date, no longitudinal neuroimaging study has tested this hypothesis in vivo in frontotemporal dementia spectrum disorders. The aim of this study was to demonstrate that longitudinal progression of atrophy in non-fluent/agrammatic variant primary progressive aphasia spreads over time from a syndrome-specific epicentre to additional regions, based on their connectivity to the epicentre in healthy control subjects...
August 6, 2016: Brain: a Journal of Neurology
Mariana Babo-Rebelo, Craig G Richter, Catherine Tallon-Baudry
UNLABELLED: The default network (DN) has been consistently associated with self-related cognition, but also to bodily state monitoring and autonomic regulation. We hypothesized that these two seemingly disparate functional roles of the DN are functionally coupled, in line with theories proposing that selfhood is grounded in the neural monitoring of internal organs, such as the heart. We measured with magnetoencephalograhy neural responses evoked by heartbeats while human participants freely mind-wandered...
July 27, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
R Nathan Spreng, W Dale Stevens, Joseph D Viviano, Daniel L Schacter
Anticorrelation between the default and dorsal attention networks is a central feature of human functional brain organization. Hallmarks of aging include impaired default network modulation and declining medial temporal lobe (MTL) function. However, it remains unclear if this anticorrelation is preserved into older adulthood during task performance, or how this is related to the intrinsic architecture of the brain. We hypothesized that older adults would show reduced within- and increased between-network functional connectivity (FC) across the default and dorsal attention networks...
September 2016: Neurobiology of Aging
Elena Bertossi, Elisa Ciaramelli
Mind-wandering, an ubiquitous expression of humans' mental life, reflects a drift of attention away from the current task towards self-generated thoughts, and has been associated with activity in the brain default network. To date, however, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated whether the ventromedial prefrontal cortex (vmPFC) is critically involved in mind-wandering, by studying the propensity to mind-wander in patients with lesion to the vmPFC (vmPFC patients), control patients with lesions not involving the vmPFC, and healthy individuals...
July 21, 2016: Social Cognitive and Affective Neuroscience
Elizabeth Andersen
The purpose of clinical practicums is to help nursing students learn from real clinical experiences. In clinical settings, nursing instructors set-aside time at the end of each clinical day for reflective, debriefing discussions that are designed to draw the students' attention to relevant information and help them understand their beliefs and experiences. The students' competence and decision-making skills are enhanced when they are able to reflect on critical incidents or everyday practice events. It is sometimes difficult, however, for instructors to engage students meaningfully in discussions and promote reflection when students are fatigued...
July 2016: Nurse Education in Practice
Joshua L Roffman, Alexandra S Tanner, Hamdi Eryilmaz, Anais Rodriguez-Thompson, Noah J Silverstein, New Fei Ho, Adam Z Nitenson, Daniel B Chonde, Douglas N Greve, Anissa Abi-Dargham, Randy L Buckner, Dara S Manoach, Bruce R Rosen, Jacob M Hooker, Ciprian Catana
Local prefrontal dopamine signaling supports working memory by tuning pyramidal neurons to task-relevant stimuli. Enabled by simultaneous positron emission tomography-magnetic resonance imaging (PET-MRI), we determined whether neuromodulatory effects of dopamine scale to the level of cortical networks and coordinate their interplay during working memory. Among network territories, mean cortical D1 receptor densities differed substantially but were strongly interrelated, suggesting cross-network regulation. Indeed, mean cortical D1 density predicted working memory-emergent decoupling of the frontoparietal and default networks, which respectively manage task-related and internal stimuli...
June 2016: Science Advances
David Maillet, Daniel L Schacter
During cognitive tasks requiring externally directed attention, activation in the default-network (DN) typically decreases below baseline levels ('deactivation'). Healthy aging is associated with reduced deactivation, which is usually attributed to a failure to suppress DN processes. Recent evidence instead suggests that older adults may be more reliant on DN than young adults when performing these tasks.
September 2016: Trends in Cognitive Sciences
Xiaojun Huang, Zhening Liu, Tumbwene E Mwansisya, Weidan Pu, Li Zhou, Chang Liu, Xudong Chen, Robert Rohrbaugh, Carla Marienfeld, Zhimin Xue, Haihong Liu
PURPOSE: To explore the acute effect of betel quid (BQ) use on functional network connectivity by comparing the global functional brain networks and their subsets before and immediately after BQ chewing. MATERIALS AND METHODS: Resting-state functional magnetic resonance imaging (fMRI) was performed in 27 healthy male participants before and just after chewing BQ on a 3.0T scanner with a gradient-echo echo planar imaging sequence. Independent component analysis (ICA) was used to determine components that represent the brain's functional networks and their spatial aspects of functional connectivity...
May 26, 2016: Journal of Magnetic Resonance Imaging: JMRI
Mark C Eldaief, Stephanie McMains, R Matthew Hutchison, Mark A Halko, Alvaro Pascual-Leone
Communication between cortical regions is necessary for optimal cognitive processing. Functional relationships between cortical regions can be inferred through measurements of temporal synchrony in spontaneous activity patterns. These relationships can be further elaborated by surveying effects of cortical lesions upon inter-regional connectivity. Lesions to cortical hubs and heteromodal association regions are expected to induce distributed connectivity changes and higher-order cognitive deficits, yet their functional consequences remain relatively unexplored...
May 25, 2016: Cerebral Cortex
Bradley C Taber-Thomas, Santiago Morales, Frank G Hillary, Koraly E Pérez-Edgar
BACKGROUND: Extreme shyness in childhood arising from behavioral inhibition (BI) is among the strongest risk factors for developing social anxiety. Although no imaging studies of intrinsic brain networks in children with BI have been reported, adults with a history of BI exhibit altered functioning of frontolimbic circuits and enhanced processing of salient, personally relevant information. BI in childhood may be marked by increased coupling of salience (insula) and default (ventromedial prefrontal cortex [vmPFC]) network hubs...
April 19, 2016: Depression and Anxiety
Ling-Li Zeng, Yang Liao, Zongtan Zhou, Hui Shen, Yadong Liu, Xufeng Liu, Dewen Hu
With great progress of space navigation technology, it becomes possible to travel beyond Earth's gravity. So far, it remains unclear whether the human brain can function normally within an environment of microgravity and confinement. Particularly, it is a challenge to figure out some neuroimaging-based markers for rapid screening diagnosis of disrupted brain function in microgravity environment. In this study, a 7-day -6° head down tilt bed rest experiment was used to simulate the microgravity, and twenty healthy male participants underwent resting-state functional magnetic resonance imaging scans at baseline and after the simulated microgravity experiment...
April 2016: Cognitive Neurodynamics
Benjamin W Mooneyham, Michael D Mrazek, Alissa J Mrazek, Jonathan W Schooler
A broad set of brain regions has been associated with the experience and training of mindfulness. Many of these regions lie within key intrinsic brain networks, including the executive control, salience, and default networks. In this paper, we review the existing literature on the cognitive neuroscience of mindfulness through the lens of network science. We describe the characteristics of the intrinsic brain networks implicated in mindfulness and summarize the relevant findings pertaining to changes in functional connectivity (FC) within and between these networks...
April 2016: Annals of the New York Academy of Sciences
Lili Long, Ling-Li Zeng, Yanmin Song, Hui Shen, Peng Fang, Linlin Zhang, Lin Xu, Jian Gong, Yun-Ci Zhang, Yong Zhang, Pinting Zhou, Sha Huang, Si Chen, Yuanyuan Xie, Dewen Hu, Bo Xiao
OBJECTIVE: The pathogenesis of benign adult familial myoclonic epilepsy (BAFME) remains unknown, although cerebellar pathologic changes and brain hyperexcitability have been reported. We used resting-state functional magnetic resonance imaging (fMRI) to examine the functional connectivity between the cerebellum and cerebrum in a Chinese family with BAFME for the first time. METHODS: Eleven adults with BAFME and 15 matched healthy controls underwent resting-state blood oxygen level-dependent (BOLD) fMRI scanning...
June 2016: Epilepsia
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