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Disturbed sleep is a key symptom in major depressive disorder (MDD). REM sleep alterations are well described in the current literature, but little is known about non-REM sleep alterations. Additionally, sleep disturbances relate to a variety of cognitive symptoms in MDD, but which features of non-REM sleep EEG contribute to this, remains unknown. We comprehensively analyzed non-REM sleep EEG features in three independently collected datasets (N=284). These included MDD patients with a broaddoi:10.1101/2021.03.19.436132 fatcat:dpookrgecvco7a6o4yghjo3d7i
more »... range, varying duration and severity of depression, unmedicated or medicated, age- and gender-matched to healthy controls. We explored changes in sleep architecture including sleep stages and cycles, spectral power, sleep spindles, slow waves (SW), and SW-spindle coupling. Next, we analyzed the association of these sleep features with acute measures of depression severity and overnight consolidation of procedural memory. Overall, no major systematic alterations in non-REM sleep architecture were found in patients compared to controls. For the microstructure of non-REM sleep, we observed a higher spindle amplitude in unmedicated patients compared to controls, and after the start of antidepressant medication longer SWs with lower amplitude and a more dispersed SW-spindle coupling. In addition, long-term, but not short-term medication seemed to lower spindle density. Overnight procedural memory consolidation was impaired in medicated patients and associated with lower sleep spindle density. Our results suggest that alterations in non-REM sleep EEG might be more subtle than previously reported. We discuss these findings in the context of antidepressant medication intake and age.
In order to obtain insight into the structural flexibility of chloroplast targeting sequences, the Silene pratensis preferredoxin transit peptide was studied by circular dichroism and nuclear magnetic resonance spectroscopy. In water, the peptide is unstructured, with a minor propensity towards helix formation from Val-9 to Ser-12 and from Gly-30 to Ser-40. In 50% (v/v) trifluoroethanol, structurally independent N-and C-terminal helices are stabilized. The N-terminal helix appears to bedoi:10.1016/s0014-5793(99)00653-5 pmid:10405168 fatcat:ebtnszmp4vbqpg7zfy6tmqqzri
more »... hic, with hydrophobic and hydroxylated amino acids on opposite sides. The C-terminal helix comprises amino acids Met-29^Gly-50 and is destabilized at Gly-39. No ordered tertiary structure was observed. The results are discussed in terms of protein import into chloroplasts, in which the possible interactions between the transit peptide and lipids are emphasized. z 1999 Federation of European Biochemical Societies. Abbreviations: CD, circular dichroism; HSQC, heteronuclear single quantum correlation spectroscopy; MGDG, monogalactosyl diacylglycerol; NOESY, nuclear Overhauser enhancement spectroscopy; preFd, precursor of the Silene pratensis protein ferredoxin; preSSU, precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase from pea; TFE-d 3 , [ 2 H 3 ]tri£uoroethanol; TOCSY, total correlation spectroscopy; trFd, the 47 amino acid transit peptide of preFd followed by the amino acids Ala-48-Ser-49-Gly-50-Leu-51-Pro-52 FEBS 22112 FEBS Letters 453 (1999) 318^326
Depression is a debilitating disorder with high prevalence and socioeconomic cost, but the central processes that are altered during depressive states remain largely elusive. Here, we build on recent findings in macaques that indicate a direct causal relationship between pupil dilation and anterior cingulate cortex mediated arousal during anticipation of reward. Using pupillometry and concurrent fMRI in a sample of unmedicated participants diagnosed with major depression and healthy controls,doi:10.1101/2020.03.03.20030478 fatcat:7ctd37sk6jctplp5av5nlsz5ie
more »... observed reduced pupil dilation during reward anticipation in depressed participants with acute symptomatology. We further observed that individual differences in arousal during reward anticipation track the load and impact of depressive symptoms, a correlation that we replicated in a second sample of unmedicated depressed participants. Moreover, these group differences and correlations were mirrored at the neural level. The upregulation and maintenance of arousal during reward anticipation is a translational and well-traceable process that could prove a promising gateway to a physiologically informed patient stratification.
Frontal and parietal regions are associated with some of the most complex cognitive functions, and several frontoparietal resting-state networks can be observed in wakefulness. We used functional magnetic resonance imaging data acquired in polysomnographically validated wakefulness, light sleep, and slow-wave sleep to examine the hierarchical structure of a low-frequency functional brain network, and to examine whether frontoparietal connectivity would disintegrate in sleep. Whole-braindoi:10.3389/fneur.2012.00080 pmid:22629253 pmcid:PMC3354331 fatcat:i5w4aismlnfy7lr45rcagivlse
more »... with hierarchical cluster analysis on predefined atlases were performed, as well as regression of inferior parietal lobules (IPL) seeds against all voxels in the brain, and an evaluation of the integrity of voxel time-courses in subcortical regions-of-interest. We observed that frontoparietal functional connectivity disintegrated in sleep stage 1 and was absent in deeper sleep stages. Slow-wave sleep was characterized by strong hierarchical clustering of local submodules. Frontoparietal connectivity between IPL and superior medial and right frontal gyrus was lower in sleep stages than in wakefulness. Moreover, thalamus voxels showed maintained integrity in sleep stage 1, making intrathalamic desynchronization an unlikely source of reduced thalamocortical connectivity in this sleep stage. Our data suggest a transition from a globally integrated functional brain network in wakefulness to a disintegrated network consisting of local submodules in slow-wave sleep, in which frontoparietal inter-modular nodes may play a role, possibly in combination with the thalamus.
Stress is an everyday experience and maladaptive responses play a crucial role in the etiology of affective disorders. Despite its ubiquity, the neural underpinnings of subjective stress experiences have not yet been elucidated, particularly at an individual level. In an important advance, Goldfarb et al. showed recently that subjective stress and arousal levels in response to threatening stimuli were successfully predicted based on changes in hippocampal connectivity during the task using adoi:10.1101/2020.11.16.380220 fatcat:6gpuwttt3jatlis4z6gxdvtfyq
more »... hine learning approach. Crucially, stress responses were predicted by interpretable hippocampal connectivity networks, shedding new light on the role of the hippocampus in regulating stress reactivity. However, the authors induced stress by displaying aversive pictures, while stress research often relies on the extensively validated Trier social stress task (TSST). The TSST incorporates crucial factors such as unpredictability of success and the social-evaluative threat of the stressor thereby eliciting cortisol responses more robustly compared to threatening images. Towards generalization, cross validation within a sample as conducted by Goldfarb et al. or independent replications are important steps, but the generalizability to different stressors allows to draw broader conclusions about the potential use of hippocampal connectivity to predict subjective stress. Arguably, translating these findings to clinical applications would require a broad generalization of the results or the prediction algorithm to psychosocial stress. Here, we assessed the predictive performance of Goldfarb et al.'s algorithm for subjective stress in an independent sample using an MR adaption of the TSST. In line with Goldfarb et al., we observed robust stress-induced changes in hippocampal connectivity. However, the spatial correlation of the changes in connectivity was low indicating little convergence across alleged stress paradigms. Critically, stress-induced changes of hippocampal connectivity were not robustly predictive of subjective stress across a multiverse of analyses based on connectivity changes. Collectively, this indicates that the generalizability of the reported stress connectivity fingerprint to other stressors is limited at best, suggesting that specific tasks might require tailored algorithms to robustly predict stress above chance levels.
Please be advised that this information was generated on 2021-08-15 and may be subject to change. Article Mnemonic Training Reshapes Brain Networks to Support Superior Memory Highlights d Memory champions show distributed functional brain network connectivity changes d Mnemonic strategies for superior memory can be learned by naive subjects d Mnemonic training induces similarity with memory champion brain connectivity d Brain network dynamics of this effect differ between task and resting statedoi:10.1016/j.neuron.2017.02.003 pmid:28279356 pmcid:PMC5439266 fatcat:wcfzgcvarbfm5iamdirb4tfnpe
more »... SUMMARY Memory skills strongly differ across the general population; however, little is known about the brain characteristics supporting superior memory performance. Here we assess functional brain network organization of 23 of the world's most successful memory athletes and matched controls with fMRI during both task-free resting state baseline and active memory encoding. We demonstrate that, in a group of naive controls, functional connectivity changes induced by 6 weeks of mnemonic training were correlated with the network organization that distinguishes athletes from controls. During rest, this effect was mainly driven by connections between rather than within the visual, medial temporal lobe and default mode networks, whereas during task it was driven by connectivity within these networks. Similarity with memory athlete connectivity patterns predicted memory improvements up to 4 months after training. In conclusion, mnemonic training drives distributed rather than regional changes, reorganizing the brain's functional network organization to enable superior memory performance.
In most multidimensional nuclear magnetic resonance experiments a single and distinct coherence transfer pathway is selected by phase cycling or by pulsed field gradients. It was shown that simultaneously exploiting more than one coherence transfer pathway could increase the overall sensitivity of NMR experiments. However, sensitivity enhancement schemes described to date introduce additional delays in the pulse schemes, resulting in considerable decrease of the expected sensitivity gain whendoi:10.1006/jmre.1999.2003 pmid:10698664 fatcat:57i7id22bjhsjotauyakaqsvw4
more »... plied to biomolecules due their fast transverse relaxation. A novel sensitivity enhancement principle which increases sensitivity of an experiment by simultaneously exploiting two completely independent coherence pathways in a single NMR pulse scheme is presented in this paper. As an example an improved HNCA experiment, the HNCA ؉ , is presented, which combines the "out-andback" coherence transfer pathway used in HNCA with an "out-and-stay" experiment, analogous to HCANH, without adding any time periods compared to the conventional HNCA pulse sequence. The applicability of the HNCA ؉ was theoretically evaluated with regard to different sizes of peptides or proteins, which showed that the experimental time can be reduced twofold in ideal cases. The application of this novel experiment to a 7-kDa protein showed a 20% sensitivity gain of HNCA ؉ when compared to conventional HNCA.
Participants of the annual World Memory Championships regularly demonstrate extraordinary memory feats, such as memorising the order of 52 playing cards in 20 s or 1000 binary digits in 5 min. On a cognitive level, memory athletes use well-known mnemonic strategies, such as the method of loci. However, whether these feats are enabled solely through the use of mnemonic strategies or whether they benefit additionally from optimised neural circuits is still not fully clarified. Investigating 23doi:10.1007/s00429-017-1556-2 pmid:29138923 pmcid:PMC5869896 fatcat:2crmqehb3ng4jifl7cafgr324e
more »... ding memory athletes, we found volumes of their right hippocampus and caudate nucleus were stronger correlated with each other compared to matched controls; both these volumes positively correlated with their position in the memory sports world ranking. Furthermore, we observed larger volumes of the right anterior hippocampus in athletes. Complementing these structural findings, on a functional level, fMRI resting state connectivity of the anterior hippocampus to both the posterior hippocampus and caudate nucleus predicted the athletes rank. While a competitive interaction between hippocampus and caudate nucleus is often observed in normal memory function, our findings suggest that a hippocampal-caudate nucleus cooperation may enable exceptional memory performance. We speculate that this cooperation reflects an integration of the two memory systems at issue-enabling optimal combination of stimulus-response learning and map-based learning when using mnemonic strategies as for example the method of loci.
Nuclear-encoded, chloroplast-destined proteins are synthesized with transit sequences that contain all information to get them inside the organelle. Different proteins are imported via a general protein import machinery, but their transit sequences do not share amino acid homology. It has been suggested that interactions between transit sequence and chloroplast envelope membrane lipids give rise to recognizable, structural motifs. In this study a detailed investigation of the structural,doi:10.1021/bi000110i pmid:10889029 fatcat:6ve4mvmotrdavnidglbfuhdmse
more »... al, and topological features of an isolated transit peptide associated with mixed micelles is described. The structure of the preferredoxin transit peptide in these micelles was studied by circular dichroism (CD) and multidimensional NMR techniques. CD experiments indicated that the peptide, which is unstructured in aqueous solution, obtained helical structure in the presence of the micelles. By NMR it is shown that the micelles introduced ill-defined helical structures in the transit peptide. Heteronuclear relaxation experiments showed that the whole peptide backbone is very flexible. The least dynamic segments are two N-and C-terminal helical regions flanking an unstructured proline-rich amino acid stretch. Finally, the insertion of the peptide backbone in the hydrophobic interior of the micelle was investigated by use of hydrophobic spin-labels. The combined data result in a model of the transit peptide structure, backbone dynamics, and insertion upon its interaction with mixed micelles. † This work is part of the program Chloroplast Protein Import and was carried out under auspices of the Foundation of Life Sciences (SLW) with financial aid from The Netherlands Foundation for Scientific Research (NWO). Part of this research was supported by a grant in a program between NWO and the Russian Federation (NL-RF 047.006.004). The dynamic light scattering experiments were performed at
Conventional T2 *-weighted functional magnetic resonance imaging (fMRI) is performed with echo-planar imaging (EPI) sequences that create substantial acoustic noise. The loud acoustic noise not only affects the activation of the auditory cortex, but may also interfere with resting state and task fMRI experiments. To demonstrate the feasibility of a novel, quiet, T2 *, whole-brain blood oxygenation level-dependent (BOLD)-fMRI method, termed Looping Star, compared to conventional multislicedoi:10.1002/jmri.27073 pmid:32073206 fatcat:hf7io43ixnfglmdso2nogcgebq
more »... nt-echo EPI. Prospective. Glover stability QA phantom; 10 healthy volunteers. 3.0T: gradient echo (GE)-EPI and T2 * Looping Star fMRI. Looping Star fMRI was presented and compared to GE-EPI with a working memory (WM) task and resting state (RS) experiments. Temporal stability and acoustic measurements were obtained for both methods. Functional maps and activation accuracy were compared to evaluate the performance of the novel sequence. Mean and standard deviation values were analyzed for temporal stability and acoustic noise tests. Activation maps were assessed with one-sample t-tests and contrast estimates (CE). Paired t-tests and receiver operator characteristic (ROC) were used to compare fMRI sensitivity and performance. Looping Star presented a 98% reduction in sound pressure compared with GE-EPI, with stable temporal stability (0.09% percent fluctuation), but reduced temporal signal-to-noise ratio (tSNR) (mean difference = 15.9%). The novel method yielded consistent activations for RS and WM (83.4% and 69.5% relative BOLD sensitivity), which increased with task difficulty (mean CE 2-back = 0.56 vs. 0-back = 0.08, P < 0.05). A few differences in spatial activations were found between sequences, leading to a 4-8% lower activation accuracy with Looping Star. Looping Star provides a suitable approach for whole-brain coverage with sufficient spatiotemporal resolution and BOLD sensitivity, with only 0.5 dB above ambient noise. From the comparison with GE-EPI, further developments of Looping Star fMRI should target increased sensitivity and spatial specificity for both RS and task experiments. 2. 1.
Copyright © 2018 Almeida-Corrêa, Czisch and Wotjak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). ...doi:10.3389/fncir.2018.00042 pmid:29887796 pmcid:PMC5981681 fatcat:df2nfrl3xjewha326ye3bcf25e
The selective breeding for extreme behavior on the elevated plus-maze (EPM) resulted in two mouse lines namely high-anxiety behaving (HAB) and low-anxiety behaving (LAB) mice. Using novel behavioral tests we demonstrate that HAB animals additionally exhibit maladaptive escape behavior and defensive vocalizations, whereas LAB mice show profound deficits in escaping from approaching threats which partially results from sensory deficits. We could relate these behavioral distortions to tonicdoi:10.1101/385823 fatcat:m42yslycrfck7brosesiwpz5le
more »... in brain activity within the periaqueductal gray (PAG) in HAB mice and the superior colliculus (SC) in LAB mice, using in vivo manganese-enhanced MRI (MEMRI) followed by pharmacological or chemogenetic interventions. Therefore, midbrain-tectal structures govern the expression of both anxiety-like behavior and defensive responses. Our results challenge the uncritical use of the anthropomorphic terms anxiety or anxiety-like for the description of mouse behavior, as they imply higher cognitive processes, which are not necessarily in place.
Near-Infrared Spectroscopy Topography Concentration changes of oxygenated (D[HbO], upper panel) and deoxygenated hemoglobin (D[HbR] These authors contributed equally to this work *Correspondence: czisch ...doi:10.1016/j.cub.2011.09.029 pmid:22036177 fatcat:fsb7uffwafeutca5cioymp2swm
Citation: Czisch M, Wehrle R, Stiegler A, Peters H, Andrade K, et al. (2009) Acoustic Oddball during NREM Sleep: A Combined EEG/fMRI Study. PLoS ONE 4(8): e6749. ...doi:10.1371/journal.pone.0006749 pmid:19707599 pmcid:PMC2727699 fatcat:ocmg4dj6kbh5zn6jc7ihukdnpq
Human Brain Mapping
Elbau, Michael Czisch and Philipp G. Sämann: validated the paradigm and procedure. Anne Kühnel: performed the data analysis and Nils B. Kroemer: contributed to analyses. ...doi:10.1002/hbm.25106 pmid:32597537 pmcid:PMC7469805 fatcat:q2x4bcrhhvg4xeivnwemspefmy
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