Default-Mode-Like Network Activation in Awake Rodents

Upadhyay, Jaymin; Baker, Scott J.; Chandran, Prasant; Miller, Loan; Lee, Young Lim; Marek, Gerard J.; Sakoğlu, Ünal; Chin, Chih‐Liang; Luo, Feng; Fox, Gerard B.; Day, Mark L.

doi:10.1371/journal.pone.0027839

Cited by 95 publications

(88 citation statements)

References 44 publications

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“…rats [7][8][9] and mice [10]. Moreover since it is shown that both in human [11] and nonhuman primates [12] brain state during rest is not fully comparable with the anesthetized state, new studies increasingly start to study rsfMRI in awake rodents [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Functional MRI and functional connectivity of the visual system of awake pigeons

Groof

Jonckers

Güntürkün

et al. 2013

Behavioural Brain Research

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h i g h l i g h t sFirst study to image the whole brain of awake pigeons. We show a habituation program for MR-sessions under awake and head-fixed conditions. Movement under these conditions is minimal. First measurement of functional connectivity in a non-mammalian species. Analyses of BOLD-response and functional connectivity are feasible. a r t i c l e i n f o b s t r a c tAt present, functional MRI (fMRI) is increasingly used in animal research but the disadvantage is that the majority of the imaging is applied in anaesthetized animals. Only a few articles present results obtained in awake rodents. In this study both traditional fMRI and resting state (rsfMRI) were applied to four pigeons, that were trained to remain still while being imaged, removing the need for anesthesia. This is the first time functional connectivity measurements are performed in a non-mammalian species. Since the visual system of pigeons is a well-known model for brain asymmetry, the focus of the study was on the neural substrate of the visual system. For fMRI a visual stimulus was used and functional connectivity measurements were done with the entopallium (E; analog for the primary visual cortex) as a seed region. Interestingly in awake pigeons the left E was significantly functionally connected to the right E. Moreover we compared connectivity maps for a seed region in both hemispheres resulting in a stronger bilateral connectivity starting from left E then from right E. These results could be used as a starting point for further imaging studies in awake birds and also provide a new window into the analysis of hemispheric dominance in the pigeon.

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Section: Introductionmentioning

confidence: 99%

Functional MRI and functional connectivity of the visual system of awake pigeons

Groof

Jonckers

Güntürkün

et al. 2013

Behavioural Brain Research

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“…Direct demonstrations of the DMN activations during fMRI scans in awake animals are complicated by methodological issues such as restraint, noisy environments, and interpretational aspects (e.g., the cingulate cortex is known to be activated during anxiety) (17). Nevertheless, some evidence in awake rats suggests an emergence of a DMN-like brain state after animals have habituated to the fMRI environment (18).…”

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confidence: 99%

Basal forebrain contributes to default mode network regulation

Nair

Klaassen

Arató³

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The default mode network (DMN) is a collection of cortical brain regions that is active during states of rest or quiet wakefulness in humans and other mammalian species. A pertinent characteristic of the DMN is a suppression of local field potential gamma activity during cognitive task performance as well as during engagement with external sensory stimuli. Conversely, gamma activity is elevated in the DMN during rest. Here, we document that the rat basal forebrain (BF) exhibits the same pattern of responses, namely pronounced gamma oscillations during quiet wakefulness in the home cage and suppression of this activity during active exploration of an unfamiliar environment. We show that gamma oscillations are localized to the BF and that gamma-band activity in the BF has a directional influence on a hub of the rat DMN, the anterior cingulate cortex, during DMNdominated brain states. The BF is well known as an ascending, activating, neuromodulatory system involved in wake-sleep regulation, memory formation, and regulation of sensory information processing. Our findings suggest a hitherto undocumented role of the BF as a subcortical node of the DMN, which we speculate may be important for switching between internally and externally directed brain states. We discuss potential BF projection circuits that could underlie its role in DMN regulation and highlight that certain BF nuclei may provide potential target regions for up-or down-regulation of DMN activity that might prove useful for treatment of DMN dysfunction in conditions such as epilepsy or major depressive disorder.gamma suppression | anterior cingulate cortex | granger causality A highly consistent finding across a wide range of functional imaging studies in humans is that a network of brain regions, referred to as the "default mode network" (DMN), increases its activity during passive mental states compared with the performance of cognitive tasks. This was initially shown in a metaanalysis of several PET studies (1), in which a distribution of brain regions broadly including the medial prefrontal, retrosplenial, and anterior cingulate cortex (ACC), as well as lateral parietal and temporal cortices, was shown to be activated when subjects were in a state of quiet restfulness. The DMN areas are thought to form a cohesive set of intrinsically coupled brain regions, such that fMRI activations in its component regions exhibit similar time courses, allowing them to be identified reliably using seed-region analysis (2-4). Activity in the DMN exhibits anticorrelation with a complementary, largely nonoverlapping, set of fronto-parietal brain areas known as the "dorsal attention network" (DAN) (5). It should be noted, however, that particular brain structures may harbor functionally heterogeneous elements and thus may contribute to multiple functions, as was shown for the ACC (6). During wakefulness, the human brain thus alternates between DAN-and DMN-dominated activation states, corresponding to effortful cognitive task performance on the one hand and quiet restful...

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“…Bilateral cingulate cortex and retrosplenial cortex were simultaneously allocated into this module only under Mediso. This modular organization was very similar to the default-mode network (DMN) previously reported in rats (Upadhyay et al, 2011a;Lu et al, 2012) and mice Stafford et al, 2014;Liska et al, 2015;Zerbi et al, 2015). Therefore, it was named as DMN-like module.…”

Section: Modulessupporting

confidence: 76%

“…It was reported by some previous rodent rs-fMRI studies with variations in the involved brain areas (Upadhyay et al, 2011b;Lu et al, 2012;Schwarz et al, 2013;Sforazzini et al, 2014;Stafford et al, 2014;Liska et al, 2015;Zerbi et al, 2015). However, anterior cingulate cortex was only assigned into the DMN-like module in Mediso group, which is more in line with most DMN studies.…”

Section: Similar Modules Were Detected Across Agentssupporting

confidence: 76%

Functional network study on the wild type and DISC1 transgenic mice

Wu¹

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Major mental disorders such as schizophrenia (SZ), bipolar disorder and major depression create a heavy social burden and remain poorly treated. Recent reports examining the genetic and molecular structure of brain disorders discovered the gene Disrupted-in-Schizophrenia 1 (DISC1) to be significantly associated with these disorders and plays a substantial role in influencing a range of shared endophenotypes underlying these disorders. This has led to a powerful gateway to explore the underlying pathology and to achieve better diagnosis and treatments of major mental diseases. Characterising the phenotypes of DISC1 in brain functions would provide valuable insights into the mechanism of how this gene influences the brain.Resting-state fMRI (rs-fMRI) is a powerful technique being applied to more than 30 different kinds of brain disorders and different species. Findings from rs-fMRI studies on humans provide ample evidence of abnormal functional patterns in patients with mental illnesses. Specifically, altered functional connectivity (FC) and network topologies are proposed to be plausible imaging endophenotypes of psychotic disorders. However, little is known about the direct effects of gene dysfunction, such as DISC1 mutations, on restingstate brain activations. One aim of this thesis is to investigate the impacts of DISC1 on variations of resting-state functional networks (RSNs) in anaesthetized mouse brains using DISC1 transgenic mice and rs-fMRI.Before characterizing disease phenotypes in mouse models, it is necessary to understand how the mouse brain functions in normal states. Anaesthesia is currently an integrated part of most mouse rs-fMRI experiment. However, it influences blood-oxygenation-leveldependent (BOLD) fMRI signals via modulation of neurovascular coupling and brain metabolism, and therefore alters FC and topologies of RSNs. Investigating FC and its changes associated with genes therefore initially requires an understanding of the anaesthetics. Furthermore, various anaesthetic protocols are adopted by different labs leading to difficulties in result comparisons. The brain is a complex and hierarchical system, whereby its RSN architecture can be characterised from mutiple perspectives at regional or global levels. Previous mouse rs-fMRI studies have focused on long-distance FC, however, given the non-uniform influence of anaesthesia on the brain, mapping functional activations across scales in mice under different anaesthetics remain sparsely explored. Establishing this relationahsip would provide a reliable reference to study mouse brain functions in abnormal states and facilitate comparisons across laboratories. | P a g eIn the first aim of this thesis, I investigated the local connectivity in wide type (WT) mice under six commonly used anaesthetic regimens. I identified that the regional connectivity altered across the brain as a function of the expression density of receptors relative to specific agents. In addition, the depth of anaesthesia influences local synchronization.In the seco...

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Default-Mode-Like Network Activation in Awake Rodents

Cited by 95 publications

References 44 publications

Functional MRI and functional connectivity of the visual system of awake pigeons

Functional MRI and functional connectivity of the visual system of awake pigeons

Basal forebrain contributes to default mode network regulation

Functional network study on the wild type and DISC1 transgenic mice

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