Articles de revues : « HEMISPHERIC ASYMMETRY ANALYSES »

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van Orden, Karl F., et John F. House. « Spatial Frequency-Dependent Asymmetry of Visual Evoked Potential Amplitudes ». Perceptual and Motor Skills 82, n^o 3 (juin 1996) : 1011–18. http://dx.doi.org/10.2466/pms.1996.82.3.1011.

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The extent to which pattern reversal evoked potential amplitudes are distributed symmetrically over the scalp was investigated as a function of stimulus spatial frequency. Nine right-handed male subjects viewed sinusoidal grating stimuli of 4.0 and 0.5 c/deg phase reversed every 900 msec. A visual half-field configuration enabled selective stimulation of the right- or left-hemisphere visual cortex. Evoked responses were recorded from the 2 cm above the inion (Oz) and at 7 and 13 cm lateral to Oz. Analyses of normalized evoked response amplitudes showed a significant asymmetry for the 4.0 c/deg stimulus; right-hemisphere amplitudes declined as a function of distance from the midline, while left-hemisphere amplitudes were greatest at the 7 cm recording site. No hemispheric differences were observed for the 0.5 c/deg stimulus; amplitudes for both hemispheres declined as a function of distance from the midline. The data are discussed in terms of hemispheric differences in morphology and functional asymmetries at early levels of sensory processing.

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Cao, Rui, Huiyu Shi, Xin Wang, Shoujun Huo, Yan Hao, Bin Wang, Hao Guo et Jie Xiang. « Hemispheric Asymmetry of Functional Brain Networks under Different Emotions Using EEG Data ». Entropy 22, n^o 9 (26 août 2020) : 939. http://dx.doi.org/10.3390/e22090939.

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Despite many studies reporting hemispheric asymmetry in the representation and processing of emotions, the essence of the asymmetry remains controversial. Brain network analysis based on electroencephalography (EEG) is a useful biological method to study brain function. Here, EEG data were recorded while participants watched different emotional videos. According to the videos’ emotional categories, the data were divided into four categories: high arousal high valence (HAHV), low arousal high valence (LAHV), low arousal low valence (LALV) and high arousal low valence (HALV). The phase lag index as a connectivity index was calculated in theta (4–7 Hz), alpha (8–13 Hz), beta (14–30 Hz) and gamma (31–45 Hz) bands. Hemispheric networks were constructed for each trial, and graph theory was applied to quantify the hemispheric networks’ topological properties. Statistical analyses showed significant topological differences in the gamma band. The left hemispheric network showed significantly higher clustering coefficient (Cp), global efficiency (Eg) and local efficiency (Eloc) and lower characteristic path length (Lp) under HAHV emotion. The right hemispheric network showed significantly higher Cp and Eloc and lower Lp under HALV emotion. The results showed that the left hemisphere was dominant for HAHV emotion, while the right hemisphere was dominant for HALV emotion. The research revealed the relationship between emotion and hemispheric asymmetry from the perspective of brain networks.

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Bhowmik, Prantika. « Polar flux imbalance at the sunspot cycle minimum governs hemispheric asymmetry in the following cycle ». Astronomy & ; Astrophysics 632 (décembre 2019) : A117. http://dx.doi.org/10.1051/0004-6361/201834425.

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Aims. Hemispheric irregularities of solar magnetic activity is a well-observed phenomenon, the origin of which has been studied through numerical simulations and data analysis techniques. In this work we explore possible causes generating north-south asymmetry in the reversal timing and amplitude of the polar field during cycle minimum. Additionally, we investigate how hemispheric asymmetry is translated from cycle to cycle. Methods. We pursued a three-step approach. Firstly, we explored the asymmetry present in the observed polar flux and sunspot area by analysing observational data of the last 110 years. Secondly, we investigated the contribution from various factors involved in the Babcock–Leighton mechanism to the evolution and generation of polar flux by performing numerical simulations with a surface flux transport model and synthetic sunspot input profiles. Thirdly, translation of hemispheric asymmetry in the following cycle was estimated by assimilating simulation-generated surface magnetic field maps at cycle minimum in a dynamo simulation. Finally, we assessed our understanding of hemispheric asymmetry in the context of observations by performing additional observational data-driven simulations. Results. Analysis of observational data shows a profound connection between the hemispheric asymmetry in the polar flux at cycle minimum and the total hemispheric activity during the following cycle. We find that the randomness associated with the tilt angle of sunspots is the most crucial element among diverse components of the Babcock–Leighton mechanism in resulting hemispheric irregularities in the evolution of polar field. Our analyses with dynamo simulations indicate that an asymmetric poloidal field at the solar minimum can introduce significant north-south asymmetry in the amplitude and timing of peak activity during the following cycle. While observational data-driven simulations reproduce salient features of the observed asymmetry in the solar cycles during the last 100 years, we speculate that fluctuations in the mean-field α-effect and meridional circulation can have finite contributions in this regard.

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Vyazovskiy, V. V., et I. Tobler. « Handedness Leads to Interhemispheric EEG Asymmetry During Sleep in the Rat ». Journal of Neurophysiology 99, n^o 2 (février 2008) : 969–75. http://dx.doi.org/10.1152/jn.01154.2007.

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Sleep electroencephalographic (EEG) slow-wave activity is increased after wakefulness and decreases during sleep. Regional sleep EEG differences are thought to be a consequence of activation of specific cortical neuronal circuits during waking. We investigated the relationship between handedness and interhemispheric brain asymmetry. Bilateral EEG recordings were obtained from the frontal and occipital cortex in rats with a clear paw preference in a food-reaching task (right, n = 5; left, n = 5). While still naïve to the task, no waking or sleep EEG asymmetry was present. During the food-reaching task, the waking EEG showed significant, substantial power increases in the frontal hemisphere contralateral to the dominant paw in the low theta range (4.5–6.0 Hz). Moreover, the non-REM sleep EEG following feeding bouts was markedly asymmetric, with significantly higher power in the hemisphere contralateral to the preferred paw in frequencies >1.5 Hz. No asymmetry was evident in the occipital EEG. Correlation analyses revealed a positive association between the hemispheric asymmetry during sleep and the degree of preferred use of the contralateral paw during waking in frequencies <9.0 Hz. Our findings show that handedness is reflected in specific, regional EEG asymmetry during sleep. Neuronal activity induced by preferential use of a particular forelimb led to a local enhancement of EEG power in frequencies within the delta and sigma ranges, supporting the hypothesis of use-dependent local sleep regulation. We conclude that inherent laterality is manifested when animals are exposed to complex behavioral tasks, and sleep plays a role in consolidating the hemispheric dominance of the brain.

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Nepomnyashchikh, Alexander, Sudip Mandal, Dipankar Banerjee et Leonid Kitchatinov. « Can the long-term hemispheric asymmetry of solar activity result from fluctuations in dynamo parameters ? » Astronomy & ; Astrophysics 625 (mai 2019) : A37. http://dx.doi.org/10.1051/0004-6361/201935224.

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Context. The hemispheric asymmetry of sunspot activity observed possesses a regular component varying on a timescale of several solar cycles whose origin and properties are currently debated. Aims This paper addresses the question of whether the long-term hemispheric asymmetry can result from random variations of solar dynamo parameters in time and latitude. Methods. Scatter in the observed tilt angles of sunspot groups was estimated to infer constraints on fluctuations in the dynamo mechanism for poloidal field regeneration. A dynamo model with fluctuations in the Babcock-Leighton type α-effect was designed in accordance with these constraints and then used to compute a large number of magnetic cycles for statistical analyses of their hemispheric asymmetry. Results Hemispheric asymmetry in the simulated dynamo results from the presence of an equator-symmetric part in the oscillating magnetic field. The sub-dominant quadrupolar oscillations are stochastically forced by dominant dipolar oscillations via the equator-symmetric part of the fluctuating α-effect. The amplitude and sense of the asymmetry of individual cycles varies on a timescale of the order of four dynamo-cycle periods. The variations are irregular and not periodic. The model suggests that asymmetry in the polar magnetic fields in the solar minima can be used as a precursor for asymmetry of sunspot activity in the following solar cycle.

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Proverbio, Alice Mado, et Alberto Zani. « Hemispheric Asymmetry in Visual Processing : An ERP Study on Spatial Frequency Gratings ». Symmetry 13, n^o 2 (23 janvier 2021) : 180. http://dx.doi.org/10.3390/sym13020180.

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A hemispheric asymmetry for the processing of global versus local visual information is known. In this study, we investigated the existence of a hemispheric asymmetry for the visual processing of low versus high spatial frequency gratings. The event-related potentials were recorded in a group of healthy right-handed volunteers from 30 scalp sites. Six types of stimuli (1.5, 3 and 6 c/deg gratings) were randomly flashed 180 times in the left and right upper hemifields. The stimulus duration was 80 ms, and the interstimulus interval (ISI) ranged between 850 and 1000 ms. Participants paid attention and responded to targets based on their spatial frequency and location. The C1 and P1 visual responses, as well as a later selection negativity and a P300 component of event-related potentials (ERPs), were quantified and subjected to repeated-measure analyses of variance (ANOVAs). Overall, the performance was faster for the right visual field (RVF), thus suggesting a left hemispheric advantage for the attentional selection of local elements. Similarly, the analysis of the mean area amplitude of the C1 (60–110 ms) sensory response showed a stronger attentional effect (F+L+ vs. F−L+) at the left occipital areas, thus suggesting the sensory nature of this hemispheric asymmetry.

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Amodio, R., A. Prinster, A. M. Monteleone, F. Esposito, A. Canna, E. Cantone, U. Volpe et P. Monteleone. « Interhemispheric functional connectivity in anorexia and bulimia nervosa ». European Psychiatry 41, S1 (avril 2017) : S551. http://dx.doi.org/10.1016/j.eurpsy.2017.01.781.

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IntroductionThe functional interplay between brain hemispheres is fundamental for behavioral, cognitive and emotional control. Several pathophysiological aspects of eating disorders (EDs) have been investigated by the use of functional Magnetic Resonance Imaging (fMRI).ObjectivesThe objective of the study was to investigate functional brain asymmetry of resting-state fMRI correlations in symptomatic patients with anorexia nervosa (AN) and bulimia nervosa (BN).AimsWe aimed at revealing whether brain regions implicated in reward, cognitive control, starvation and emotion regulation show altered inter-hemispheric functional connectivity in patients with AN and BN.MethodsUsing resting-state fMRI, voxel-mirrored homotopic connectivity (VMHC) and regional inter-hemispheric spectral coherence (IHSC) analyses in two canonical slow frequency bands (“Slow-5”, “Slow-4”) were studied in 15AN and 13BN patients and 16 healthy controls (HC). Using T1-weighted and diffusion tensor imaging MRI scans, regional VMHC values were correlated with the left-right asymmetry of corresponding homotopic gray matter volumes and with the white matter callosal fractional anisotropy (FA).ResultsCompared to HC, AN patients exhibited reduced VMHC in cerebellum, insula and precuneus, while BN patients showed reduced VMHC in dorso-lateral prefrontal and orbito-frontal cortices. The regional IHSC analysis highlighted that the inter-hemispheric functional connectivity was higher in the ‘Slow-5′Band in all regions except the insula. No group differences in left-right structural asymmetries and in VMHC vs callosal FA correlations were found.ConclusionsThese anomalies indicate that AN and BN, at least in their acute phase, are associated with a loss of inter-hemispheric connectivity in regions implicated in self-referential, cognitive control and reward processing.Disclosure of interestThe authors have not supplied their declaration of competing interest.

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Ambrosini, Ettore, et Antonino Vallesi. « Domain-general Stroop Performance and Hemispheric Asymmetries : A Resting-state EEG Study ». Journal of Cognitive Neuroscience 29, n^o 5 (mai 2017) : 769–79. http://dx.doi.org/10.1162/jocn_a_01076.

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The ability to suppress irrelevant information while executing a task, also known as interference resistance ability, is a function of pFC that is critical for successful goal-directed human behavior. In the study of interference resistance and, more generally, executive functions, two key questions are still open: Does pFC contribute to cognitive control abilities through lateralized but domain-general mechanisms or through hemispheric specialization of domain-specific processes? And what are the underlying causes of interindividual differences in executive control performance? To shed light on these issues, here we employed an interindividual difference approach to investigate whether participants' hemispheric asymmetry in resting-state electrophysiological brain dynamics may reflect their variability in domain-general interference resistance. We recorded participants' resting-state electroencephalographic activity and performed spectral power analyses on the estimated cortical source activity. To measure participants' lateralized brain dynamics at rest, we computed the right–left hemispheric asymmetry score for the β/α power ratio. To measure their domain-general interference resistance ability, verbal and spatial Stroop tasks were used. Robust correlations followed by intersection analyses showed that participants with stronger resting-state-related left-lateralized activity in different pFC regions, namely the mid-posterior superior frontal gyrus, middle and posterior middle frontal gyrus, and inferior frontal junction, were more able to inhibit irrelevant information in both domains. The present results confirm and extend previous findings showing that neurophysiological difference factors may explain interindividual differences in executive functioning. They also provide support for the hypothesis of a left pFC hemispheric specialization for domain-independent phasic cognitive control processes mediating Stroop performance.

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Christou, Antonios I., Satoshi Endo, Yvonne Wallis, Hayley Bair, Maurice P. Zeegers et Joseph P. McCleery. « Variation in serotonin transporter linked polymorphic region (5-HTTLPR) short/long genotype modulates resting frontal electroencephalography asymmetries in children ». Development and Psychopathology 28, n^o 1 (20 mai 2015) : 239–50. http://dx.doi.org/10.1017/s0954579415000413.

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AbstractPrevious studies have documented the serotonin transporter linked polymorphic region (5-HTTLPR) as a genetic susceptibility variant that contributes to variability in outcomes related to affective psychopathology, with the short allele associated with negative affectivity and the long allele associated with positive affectivity. In a separate but related line of research, extensive evidence suggests that frontal electroencephalography (EEG) hemispheric asymmetry in the alpha band is also associated with risk for affective psychopathologies, with leftward asymmetry associated with approach-related behavior patterns and rightward frontal EEG asymmetry associated with withdrawn behavioral tendencies. We examined frontal EEG hemispheric asymmetries in relation to 5-HTTLPR genotyping in 70 children between 4 and 6 years of age. Analyses revealed that frontal EEG lateralization interacted with genotype such that children homozygous for the short allele exhibited rightward frontal EEG asymmetries, children who were homozygous for the long allele consistently exhibited a positive pattern of leftward asymmetry, and heterozygotes exhibited equivalent left and right frontal activity. These findings suggest that the 5-HTTLPR short allele may provide a degree of susceptibility for later affective psychopathology in adolescence and adulthood, through mediation of frontal brain activity that is associated with cognitive–behavioral withdrawal tendencies and negative affectivity.

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Shu, Ni, Yaou Liu, Yunyun Duan et Kuncheng Li. « Hemispheric Asymmetry of Human Brain Anatomical Network Revealed by Diffusion Tensor Tractography ». BioMed Research International 2015 (2015) : 1–11. http://dx.doi.org/10.1155/2015/908917.

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The topological architecture of the cerebral anatomical network reflects the structural organization of the human brain. Recently, topological measures based on graph theory have provided new approaches for quantifying large-scale anatomical networks. However, few studies have investigated the hemispheric asymmetries of the human brain from the perspective of the network model, and little is known about the asymmetries of the connection patterns of brain regions, which may reflect the functional integration and interaction between different regions. Here, we utilized diffusion tensor imaging to construct binary anatomical networks for 72 right-handed healthy adult subjects. We established the existence of structural connections between any pair of the 90 cortical and subcortical regions using deterministic tractography. To investigate the hemispheric asymmetries of the brain, statistical analyses were performed to reveal the brain regions with significant differences between bilateral topological properties, such as degree of connectivity, characteristic path length, and betweenness centrality. Furthermore, local structural connections were also investigated to examine the local asymmetries of some specific white matter tracts. From the perspective of both the global and local connection patterns, we identified the brain regions with hemispheric asymmetries. Combined with the previous studies, we suggested that the topological asymmetries in the anatomical network may reflect the functional lateralization of the human brain.

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Byczynski, Gabriel, Kylie Schibli, Gary Goldfield, Gerry Leisman et Amedeo D’Angiulli. « EEG Power Band Asymmetries in Children with and without Classical Ensemble Music Training ». Symmetry 14, n^o 3 (7 mars 2022) : 538. http://dx.doi.org/10.3390/sym14030538.

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Much evidence shows that music training influences the development of functional brain organization and cerebral asymmetry in an auditory-motor integrative neural system also associated with language and speech. Such overlap suggests that music training could be used for interventions in disadvantaged populations. Accordingly, we investigated neurofunctional changes associated with the influence of socially based classical ensemble music (CEM) training on executive auditory functions of children from low socioeconomic status (LSES), as compared to untrained counterparts. We conducted a novel ROI-focused reanalysis of stimulus-locked event-related electroencephalographic (EEG) band power data previously recorded from fifteen LSES children (9–10 years), with and without CEM, while performing a series of auditory Go/No-Go trials (involving 1100 Hz or 2000 Hz tones). An analysis of collapsed Alpha2, Beta1, Beta2, Delta, and Theta EEG bands showed significant differences in increased and decreased left asymmetry between the CEM and the Comparison group in key frontal and central electrodes typically associated with learning music. Overall, in Go trials, the CEM group responded more quickly and accurately. Linear regression analyses revealed both positive and negative correlations between left hemispheric asymmetry and behavioral measures of PPVT score, auditory sensitivity, Go accuracy, and reaction times. The pattern of results suggests that tone frequency and EEG asymmetries may be attributable to a shift to left lateralization as a byproduct of CEM. Our findings suggest that left hemispheric laterality associated with ensemble music training may improve the efficiency of productive language processing and, accordingly, may be considered as a supportive intervention for LSES children and youth.

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Wang, Kai, Xiujun Wang, Raghu Murtugudde, Dongxiao Zhang et Rong-Hua Zhang. « Sensitivity of asymmetric oxygen minimum zones to mixing intensity and stoichiometry in the tropical Pacific using a basin-scale model (OGCM-DMEC V1.4) ». Geoscientific Model Development 15, n^o 3 (3 février 2022) : 1017–35. http://dx.doi.org/10.5194/gmd-15-1017-2022.

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Abstract. The tropical Pacific Ocean holds the two largest oxygen minimum zones (OMZs) in the world's oceans, showing a prominent hemispheric asymmetry, with a much stronger and broader OMZ north of the Equator. However, many models have difficulties in reproducing the observed asymmetric OMZs in the tropical Pacific. Here, we apply a fully coupled basin-scale model to evaluate the impacts of stoichiometry and the intensity of vertical mixing on the dynamics of OMZs in the tropical Pacific. We first utilize observational data of dissolved oxygen (DO) to calibrate and validate the basin-scale model. Our model experiments demonstrate that enhanced vertical mixing combined with a reduced O:C utilization ratio can significantly improve our model capability of reproducing the asymmetric OMZs. Our study shows that DO concentration is more sensitive to biological processes over 200–400 m but to physical processes below 400 m. Applying an enhanced vertical mixing causes a modest increase in physical supply (1–2 mmol m−3 yr−1) and a small increase (< 0.5 mmol m−3 yr−1) in biological consumption over 200–1000 m, whereas applying a reduced O:C utilization ratio leads to a large decrease (2–8 mmol m−3 yr−1) in both biological consumption and physical supply in the OMZs. Our analyses suggest that biological consumption (greater rate to the south than to the north) cannot explain the asymmetric distribution of mid-depth DO in the tropical Pacific, but physical supply (stronger vertical mixing to the south) plays a major role in regulating the asymmetry of the tropical Pacific's OMZs. This study also highlights the important roles of physical and biological interactions and feedbacks in contributing to the asymmetry of OMZs in the tropical Pacific.

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Keller, Simon S., Neil Roberts, Marta García-Fiñana, Siawoosh Mohammadi, E. Bernd Ringelstein, Stefan Knecht et Michael Deppe. « Can the Language-dominant Hemisphere Be Predicted by Brain Anatomy ? » Journal of Cognitive Neuroscience 23, n^o 8 (août 2011) : 2013–29. http://dx.doi.org/10.1162/jocn.2010.21563.

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It has long been suspected that cortical interhemispheric asymmetries may underlie hemispheric language dominance (HLD). To test this hypothesis, we determined interhemispheric asymmetries using stereology and MRI of three cortical regions hypothesized to be related to HLD (Broca's area, planum temporale, and insula) in healthy adults in whom HLD was determined using functional transcranial Doppler sonography and functional MRI (15 left HLD, 10 right HLD). We observed no relationship between volume asymmetry of the gyral correlates of Broca's area or planum temporale and HLD. However, we observed a robust relationship between volume asymmetry of the insula and HLD (p = .008), which predicted unilateral HLD in 88% individuals (86.7% left HDL and 90% right HLD). There was also a subtle but significant positive correlation between the extent of HLD and insula volume asymmetry (p = .02), indicating that a larger insula predicted functional lateralization to the same hemispheric side for the majority of subjects. We found no visual evidence of basic anatomical markers of HLD other than that the termination of the right posterior sylvian fissure was more likely to be vertical than horizontal in right HLD subjects (p = .02). Predicting HLD by virtue of gross brain anatomy is complicated by interindividual variability in sulcal contours, and the possibility remains that morphological and cytoarchitectural organization of the classical language regions may underlie HLD when analyses are not constrained by the natural limits imposed by measurement of gyral volume. Although the anatomical correlates of HLD will most likely be found to include complex intra- and interhemispheric connections, there is the possibility that such connectivity may correlate with gray matter morphology. We suggest that the potential significance of insular morphology should be considered in future studies addressing the anatomical correlates of human language lateralization.

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Shipkova, Karine M. « Lateralization of Auditory Speech Asymmetry in Aphasic Disorders and the Influence of Its Vector on the Efficiency of Dichotic Listening to a Series of C-V-C Words and the Dynamics of Speech Recovery ». Sibirskiy Psikhologicheskiy Zhurnal, n^o 85 (2022) : 162–73. http://dx.doi.org/10.17223/17267080/85/8.

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The dichotic listening task is commonly used in a wide range of neuropsychological issues for studying interhemispheric asymmetry and interhemispheric interaction mechanisms. The article aims to determine the specific vector of auditory speech asymmetry for efferent motor and acoustic mnestic aphasia and its correlation with the dynamics of speech recovery. The paper studied the frequency of the right and left vectors of auditory speech asymmetry in aphasics with different time post-onset and structural characteristics of lesions. Also, the paper analyses the influence of the ear advantage side on the efficiency index of dichotic listening and quantitative indicators of speech. Material. Patients with acoustic mnestic (n = 52) and efferent motor aphasia (N = 58) of moderate and mild severity. Methods. The dichotic listening task: 16 paired series of 4 monosyllabic words in each. Results. Time post-onset, as well as lesion size, does not influence directly auditory speech laterality in aphasics. The frequency of occurrence of the positive and negative signs of the coefficient of the right ear has no pronounced differences between the different lesion sizes and time post-onset in aphasia. The left hemisphere lesion marks the impairment of the reciprocity in hemispheric interaction. The left ear advantage influences positively the dichotic listening efficiency index. Aphasia recovery does not have a direct conjugacy with the side of lesion or ear advantage. At the same time, the left ear advantage in acoustic mnestic aphasia creates a more pronounced “positive shift” in speech scores than in efferent motor aphasia. Conclusion. It appears that interhemispheric speech reorganization is determined apart from topical, typological, time post-onset and the left-handedness factors by others that needed to be investigated.

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Baybakov, S. E., N. S. Bakhareva, S. V. Chigrin, E. K. Gordeeva, T. R. Yusupov, E. A. Salomatina et D. D. Shevchuk. « Hemispheric Asymmetry Gender Differences in Preadolescent Children ». Innovative Medicine of Kuban, n^o 1 (6 mars 2023) : 53–57. http://dx.doi.org/10.35401/2541-9897-2023-26-1-53-57.

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Background: Investigating various postnatal parameters of cerebral hemispheres is of great practical value.Objective: To study gender differences in hemispheric parameters and interhemispheric interactions in preadolescent children.Materials and methods: The retrospective study assessed archived brain magnetic resonance images of 60 eight-year-old boys and 60 eight-year-old girls. The analyzed parameters were as follows: 1) hemispheric length; 2) hemispheric width; 3) hemispheric height; 4) width-longitudinal index of a hemisphere; 5) altitude-longitudinal index of a hemisphere; 6) length of frontal lobes; 7) length of parietal lobes; 8) length of occipital lobes; 9) length of temporal lobes. Quantitative indicators were assessed for normal distribution using the Kolmogorov–Smirnov test. Source data were accumulated and arranged in Microsoft Excel 2016 spreadsheets. Statistica 10.0 was used for the statistical analysis. The results were considered statistically significant with P < 0.05.Results: The analysis of cephalometric indicators suggests sex-related variation in the cerebral hemispheres. Based on the obtained data we can identify morphometric parameters of interhemispheric variability that may act as one of the morphometric criteria for the brain asymmetry. The study results can be widely used for neuroimaging.Conclusions: We determined cephalometric reference values for various cerebral hemispheres parts in preadolescent children.

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Дубасова, Анжелика. « Лексическая неоднозначность в экспериментальных исследованиях : метаанализ ». Vārds un tā pētīšanas aspekti : rakstu krājums = The Word : Aspects of Research : conference proceedings, n^o 24 (2 décembre 2020) : 43–51. http://dx.doi.org/10.37384/vtpa.2020.24.043.

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The article analyses experimental studies of lexical ambiguity (polysemy and homonymy). In total, 42 papers published between 1981 and 2017 were selected for analysis. Selected works were analyzed from the point of view of a) interaction of the main factors of lexical ambiguity resolution (meaning dominance and context), b) modularity/interactivity of language systems. The choice of these issues was caused by the fact that, despite a significant number of papers addressing them, a common theoretical model of lexical ambiguity resolution is still missing. The analysis concluded that none of the existing models could be chosen as the only true one. I believe that it is more promising to combine all models into one; in this case, we should not talk about “models” but about “algorithms” or “strategies”. This merge is compatible with the results of studies of hemispheric asymmetry, which showed that the right and left hemispheres differently process ambiguous words. This difference is projected on the difference between the two main points of view on language processing, interactive and modular. Also, as a result of the analysis, the properties of meaning dominance and context as the main factors influencing the perception of ambiguity are summarized, and the ways and possibilities of their interaction are determined. These factors can participate in the process of resolving ambiguity autonomously or together, with different functions, speed, and levels of perception.

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Angel, Lucie, Séverine Fay, Badiâa Bouazzaoui et Michel Isingrini. « Two Hemispheres for Better Memory in Old Age : Role of Executive Functioning ». Journal of Cognitive Neuroscience 23, n^o 12 (décembre 2011) : 3767–77. http://dx.doi.org/10.1162/jocn_a_00104.

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This experiment explored the functional significance of age-related hemispheric asymmetry reduction associated with episodic memory and the cognitive mechanisms that mediate this brain pattern. ERPs were recorded while young and older adults performed a word-stem cued-recall task. Results confirmed that the parietal old/new effect was of larger latency and reduced magnitude and less lateralized in the older group than the young group. Correlational and regression analyses indicated that the degree of laterality of brain activity determines the accuracy of memory performance and mediates age-related differences in memory performance among older participants. They also confirmed a cascade model in which the individual level of executive functioning of older adults mediates age-related differences in the degree of lateralization of brain activity, which in turn mediates age-related differences in memory performance.

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Shibahara, Naoki, et Brennis Lucero-Wagoner. « Hemispheric Asymmetry in Accessing Word Meanings : Concrete and Abstract Nouns ». Perceptual and Motor Skills 94, n^o 3_suppl (juin 2002) : 1292–300. http://dx.doi.org/10.2466/pms.2002.94.3c.1292.

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The present experiments investigated hemispheric differences in the brain in accessing concrete and abstract word meanings. For this purpose, an automatic semantic priming paradigm was used with a short stimulus onset asynchrony between prime and target (250 msec.) as well as a low proportion of related trials. (20%). Analysis showed that for concrete nouns, priming effects were observed in both hemispheres. There was greater priming in the right hemisphere, suggesting hemispheric differences in accessing semantic representations of concrete nouns. For abstract nouns, on the other hand, priming patterns in the right hemisphere were identical to those in the left hemisphere, suggesting that information about abstract nouns projected to the right hemisphere may be transferred to the dominant left hemisphere for further processing.

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Hamdy, Shaheen, John C. Rothwell, David J. Brooks, Dale Bailey, Qasim Aziz et David G. Thompson. « Identification of the Cerebral Loci Processing Human Swallowing With H2 15O PET Activation ». Journal of Neurophysiology 81, n^o 4 (1 avril 1999) : 1917–26. http://dx.doi.org/10.1152/jn.1999.81.4.1917.

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Identification of the cerebral loci processing human swallowing with H2 15O PET activation. Lesional and electrophysiological data implicate a role for the cerebral cortex in the initiation and modulation of human swallowing, and yet its functional neuroanatomy remains undefined. We therefore conducted a functional study of the cerebral loci processing human volitional swallowing with 15O-labeled water positron emission tomography (PET) activation imaging. Regional cerebral activation was investigated in 8 healthy right handed male volunteers with a randomized 12-scan paradigm of rest and water swallows (5 ml/bolus, continuous infusion) at increasing frequencies of 0.1, 0.2, and 0.3 Hz, which were visually cued and monitored with submental electromyogram (EMG). Group and individual linear covariate analyses were performed with SPM96. In five of eight subjects, the cortical motor representation of pharynx was subsequently mapped with transcranial magnetic stimulation (TMS) in a posthoc manner to substantiate findings of hemispheric differences in sensorimotor cortex activation seen with PET. During swallowing, group PET analysis identified increased regional cerebral blood flow (rCBF) ( P < 0.001) within bilateral caudolateral sensorimotor cortex [Brodmann’s area (BA) 3, 4, and 6], right anterior insula (BA 16), right orbitofrontal and temporopolar cortex (BA 11 and 38), left mesial premotor cortex (BA 6 and 24), left temporopolar cortex and amygdala (BA 38 and 34), left superiomedial cerebellum, and dorsal brain stem. Decreased rCBF ( P < 0.001) was also observed within bilateral posterior parietal cortex (BA 7), right anterior occipital cortex (BA 19), left superior frontal cortex (BA 8), right prefrontal cortex (BA 9), and bilateral superiomedial temporal cortex (BA 41 and 42). Individual PET analysis revealed asymmetric representation within sensorimotor cortex in six of eight subjects, four lateralizing to right hemisphere and two to left hemisphere. TMS mapping in the five subjects identified condordant interhemisphere asymmetries in the motor representation for pharynx, consistent with the PET findings. We conclude that volitional swallowing recruits multiple cerebral regions, in particular sensorimotor cortex, insula, temporopolar cortex, cerebellum, and brain stem, the sensorimotor cortex displaying strong degrees of interhemispheric asymmetry, further substantiated with TMS. Such findings may help explain the variable nature of swallowing disorders after stroke and other focal lesions to the cerebral cortex.

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Zhang, X. J., L. H. Deng, Z. P. Qiang, Y. Fei, X. A. Tian et C. Li. « Hemispheric distribution of coronal mass ejections from 1996 to 2020 ». Monthly Notices of the Royal Astronomical Society 520, n^o 3 (15 février 2023) : 3923–36. http://dx.doi.org/10.1093/mnras/stad323.

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ABSTRACT Solar magnetic structures are known to be asymmetrically distributed between the two hemispheres. To date, the hemispheric variations of the coronal mass ejections (CMEs) at different latitudes, in different cycles, and for different types (regular and specific events) are still unclear. From the list of white-light CMEs in the Coordinated Data Analysis Web catalogue, we investigate the hemispheric asymmetry of high-latitude and low-latitude CMEs in the time interval from 1996 January to 2020 December. The main results are shown for the following: (1) in each hemisphere, regular CMEs are significantly correlated with solar activity, particularly for low latitudes. However, specific CMEs are not correlated with solar activity; (2) the main reason for the hemispheric asymmetry of the CMEs is attributable to specific CMEs, not regular CMEs. The hemispheric asymmetry of high-latitude CMEs appears to have little connection to that of low-latitude CMEs; (3) for the total and specific CMEs, the relationship between the absolute asymmetry index at high and low latitudes has a positive correlation prior to the cycle maximum, but a negative correlation after the cycle maximum; and (4) the dominant hemisphere, the cumulative trend, and the amplitude of the total, specific, and regular CMEs in cycle 23 differ from those in cycle 24. Our analysis results could be useful for understanding the cyclical variation of the magnetic free energy during different solar cycles, and could also provide insight into more physical processes responsible for the solar–terrestrial relationship.

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Hayakawa, Hisashi, Kentaro Hattori, Mitsuru Sôma, Tomoya Iju, Bruno P. Besser et Shunsuke Kosaka. « An Overview of Sunspot Observations in 1727–1748 ». Astrophysical Journal 941, n^o 2 (1 décembre 2022) : 151. http://dx.doi.org/10.3847/1538-4357/ac6671.

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Abstract Solar activity generally exhibits cyclic behavior in terms of sunspot group number and sunspot positions every ≈11 yr. These sunspot data have therefore played key roles in numerous analyses of solar–terrestrial physics. However, their reconstructions prior to the 1830s have remained controversial and included significant data gaps, especially from the 1720s to the 1740s. Therefore, this study reviewed contemporary sunspot observations for 1727–1748 to add several forgotten records by Van Coesfelt in 1728–1729, Dûclos in 1736, Martin in 1737, and Cassini and Maraldi in 1748. On the basis of these records, this study revised the sunspot group number and newly derived the sunspot positions in this interval. The results show clearer solar cycles in sunspot group number than those of previous studies and indicate regular solar cycles with limited hemispheric asymmetry over Solar Cycles 0 to −2. The sunspot positions also show sunspot groups mostly at heliographic latitude φ fulfilling ∣φ∣ < 35° in both solar hemispheres, with slight equatorward motions. Furthermore, the solar minima between Solar Cycles −2 and −1 and between Solar Cycles −1 and 0 have been located around 1733.5 ± 0.5 and 1743 ± 0.5, indicating cycle lengths of 11.7 ± 0.5 yr and 10.0 ± 1.0 yr, respectively. Our results provide a chronological missing link between the Maunder Minimum and the regular solar cycles observed since Staudach’s observations from 1749 onward. This lets us better understand the transition of solar activity from the grand minimum to the regular solar cycles.

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Chen, Aihong, Yue Deng, Xiaobing Zuo et Suting Zhong. « Alteration in Asymmetry of White Matter Network of Parkinson’s Disease ». Contrast Media & ; Molecular Imaging 2022 (4 juillet 2022) : 1–8. http://dx.doi.org/10.1155/2022/8493729.

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Parkinson’s disease (PD) is manifest clinically by an asymmetrical presentation of motor dysfunction. A large number of previous neuroimaging research studies have stated the alteration in the hemispheric asymmetry of morphological features in PD disease. Diffusion Magnetic Resonance Imaging (MRI), which is noninvasive, has been widely used to quantify the white matter network in the human brain of both healthy subjects and patients. Besides, graph theory analysis is widely used to quantify the topological architecture of the human brain network. Lately, researchers have discovered that the topological architecture of the white matter network significantly differs in PD compared with healthy controls (HC). Nevertheless, the asymmetry of the topological architecture of the white matter network for PD patients remains unclear. To clarify this, the diffusion-weighted images and tractography technique were used to reconstruct the hemispherical white matter networks for 22 bilateral PD patients and 18 HC subjects. Network-based statistical analysis and graph theory analysis approaches were employed to estimate the asymmetry at both the connectivity level and the hemispheric topological level for PD patients. We found that the PD group showed atypically right-higher-than-left asymmetry in hemispheric brain global and local efficiencies. The detected right-higher-than-left asymmetry was driven by the atypically topological changes in the left hemispheric brain in the PD group. Findings from these studies might provide new insights into the asymmetric features of hemispheric disconnectivity and emphasize that the topological asymmetry of the hemispheric brain could be used as a biomarker to identify PD individuals.

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Calmels, Marie-Noëlle, Yohan Gallois, Mathieu Marx, Olivier Deguine, Soumia Taoui, Emma Arnaud, Kuzma Strelnikov et Pascal Barone. « Functional Reorganization of the Central Auditory System in Children with Single-Sided Deafness : A Protocol Using fNIRS ». Brain Sciences 12, n^o 4 (22 mars 2022) : 423. http://dx.doi.org/10.3390/brainsci12040423.

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In children, single-sided deafness (SSD) affects the development of linguistic and social skills and can impede educational progress. These difficulties may relate to cortical changes that occur following SSD, such as reduced inter-hemispheric functional asymmetry and maladaptive brain plasticity. To investigate these neuronal changes and their evolution in children, a non-invasive technique is required that is little affected by motion artifacts. Here, we present a research protocol that uses functional near-infrared spectroscopy (fNIRS) to evaluate the reorganization of cortical auditory asymmetry in children with SSD; it also examines how the cortical changes relate to auditory and language skills. The protocol is designed for children whose SSD has not been treated, because hearing restoration can alter both brain reorganization and behavioral performance. We propose a single-center, cross-sectional study that includes 30 children with SSD (congenital or acquired moderate-to-profound deafness) and 30 children with normal hearing (NH), all aged 5–16 years. The children undergo fNIRS during monaural and binaural stimulation, and the pattern of cortical activity is analyzed using measures of the peak amplitude and area under the curve for both oxy- and deoxyhemoglobin. These cortical measures can be compared between the two groups of children, and analyses can be run to determine whether they relate to binaural hearing (speech-in-noise and sound localization), speech perception and production, and quality of life (QoL). The results could be of relevance for developing individualized rehabilitation programs for SSD, which could reduce patients’ difficulties and prevent long-term neurofunctional and clinical consequences.

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Bender, Frida A. M., Anders Engström, Robert Wood et Robert J. Charlson. « Evaluation of Hemispheric Asymmetries in Marine Cloud Radiative Properties ». Journal of Climate 30, n^o 11 (8 mai 2017) : 4131–47. http://dx.doi.org/10.1175/jcli-d-16-0263.1.

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Abstract The hemispheric symmetry of albedo and its contributing factors in satellite observations and global climate models is evaluated. The analysis is performed on the annual mean time scale, on which a bimodality in the joint distribution of albedo and cloud fraction is evident, resulting from tropical and subtropical clouds and midlatitude clouds, respectively. Hemispheric albedo symmetry is not found in individual ocean-only latitude bands; comparing the Northern and Southern Hemisphere (NH and SH), regional mean albedo is higher in the NH tropics and lower in the NH subtropics and midlatitudes than in the SH counterparts. This follows the hemispheric asymmetry of cloud fraction. In midlatitudes and tropics the hemispheric asymmetry in cloud albedo also contributes to the asymmetry in total albedo, whereas in the subtropics the cloud albedo is more hemispherically symmetric. According to the observations, cloud contributions to compensation for higher clear-sky albedo in the NH come primarily from cloud albedo in midlatitudes and cloud amount in the subtropics. Current-generation climate models diverge in their representation of these relationships, but common features of the model–data comparison include weaker-than-observed asymmetry in cloud fraction and cloud albedo in the tropics, weaker or reversed cloud fraction asymmetry in the subtropics, and agreement with observed cloud albedo asymmetry in the midlatitudes. Models on average reproduce the NH–SH asymmetry in total albedo over the 60°S–60°N ocean but show higher occurrence of brighter clouds in the SH compared to observations. The albedo bias in both hemispheres is reinforced by overestimated clear-sky albedo in the models.

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Kim, Jeongchul, Youngkyoo Jung, Richard Barcus, Jocelyne H. Bachevalier, Mar M. Sanchez, Michael A. Nader et Christopher T. Whitlow. « Rhesus Macaque Brain Developmental Trajectory : A Longitudinal Analysis Using Tensor-Based Structural Morphometry and Diffusion Tensor Imaging ». Cerebral Cortex 30, n^o 8 (2 avril 2020) : 4325–35. http://dx.doi.org/10.1093/cercor/bhaa015.

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Abstract The typical developmental trajectory of brain structure among nonhuman primates (NHPs) remains poorly understood. In this study, we characterized the normative trajectory of developmental change among a cohort of rhesus monkeys (n = 28), ranging in age from 2 to 22 months, using structural MRI datasets that were longitudinally acquired every 3–4 months. We hypothesized that NHP-specific transient intracranial volume decreases reported during late infancy would be part of the typical developmental process, which is driven by volumetric contraction of gray matter in primary functional areas. To this end, we performed multiscale analyses from the whole brain to voxel level, characterizing regional heterogeneity, hemispheric asymmetry, and sexual dimorphism in developmental patterns. The longitudinal trajectory of brain development was explained by three different regional volumetric growth patterns (exponentially decreasing, undulating, and linearly increasing), which resulted in developmental brain volume curves with transient brain volumetric decreases. White matter (WM) fractional anisotropy increased with age, corresponding to WM volume increases, while mean diffusivity (MD) showed biphasic patterns. The longitudinal trajectory of brain development in young rhesus monkeys follows typical maturation patterns seen in humans, but regional volumetric and MD changes are more dynamic in rhesus monkeys compared with humans, with marked decreases followed by “rebound-like” increases.

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Wang, Bin, Qionghui Zhan, Ting Yan, Sumaira Imtiaz, Jie Xiang, Yan Niu, Miaomiao Liu, Gongshu Wang, Rui Cao et Dandan Li. « Hemisphere and Gender Differences in the Rich-Club Organization of Structural Networks ». Cerebral Cortex 29, n^o 11 (27 février 2019) : 4889–901. http://dx.doi.org/10.1093/cercor/bhz027.

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AbstractStructural and functional differences in brain hemispheric asymmetry have been well documented between female and male adults. However, potential differences in the connectivity patterns of the rich-club organization of hemispheric structural networks in females and males remain to be determined. In this study, diffusion tensor imaging was used to construct hemispheric structural networks in healthy subjects, and graph theoretical analysis approaches were applied to quantify hemisphere and gender differences in rich-club organization. The results showed that rich-club organization was consistently observed in both hemispheres of female and male adults. Moreover, a reduced level of connectivity was found in the left hemisphere. Notably, rightward asymmetries were mainly observed in feeder and local connections among one hub region and peripheral regions, many of which are implicated in visual processing and spatial attention functions. Additionally, significant gender differences were revealed in the rich-club, feeder, and local connections in rich-club organization. These gender-related hub and peripheral regions are involved in emotional, sensory, and cognitive control functions. The topological changes in rich-club organization provide novel insight into the hemisphere and gender effects on white matter connections and underlie a potential network mechanism of hemisphere- and gender-based differences in visual processing, spatial attention and cognitive control.

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Coelho, Chase J., Andrzej Przybyla, Vivek Yadav et Robert L. Sainburg. « Hemispheric differences in the control of limb dynamics : a link between arm performance asymmetries and arm selection patterns ». Journal of Neurophysiology 109, n^o 3 (1 février 2013) : 825–38. http://dx.doi.org/10.1152/jn.00885.2012.

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Human handedness has been described and measured from two perspectives: handedness inventories rate hand preferences, whereas other tests examine motor performance asymmetries. These two measurement approaches reflect a major controversy in a literature that defines handedness as either a preference or an asymmetry in sensorimotor processing. Over the past decade, our laboratory has developed a model of handedness based on lateralization of neural processes. This model attributes distinct control processes to each hemisphere, which in turn lead to observable interlimb sensorimotor performance asymmetries. We now hypothesize that arm preference, or choice, may depend on the interaction between sensorimotor performance asymmetries and the given task. The purpose of this study is to examine whether arm selection is linked to interlimb performance asymmetries during reaching. Right-handed subjects made choice and nonchoice reaches to each of eight targets ( d = 3.5 cm) arranged radially ( r = 13 cm) around a midline starting position. We displaced each cursor (one associated with each hand) 30 cm to the midline start circle to ensure that there were no hemispace-related geometric, mechanical, or perceptual biases to use either arm for the two midline targets. The three targets on each side of the midline received mostly reaches from the ipsilateral arm, a tendency previously described as a “hemispace bias.” However, the midline targets, which were equidistant from each hand, received more dominant arm reaches. Dominant arm hand paths to these targets were straighter and more accurately directed. Inverse dynamics analyses revealed a more proficient dominant arm strategy that exploited intersegmental dynamics to a greater extent than did the nondominant arm. These findings suggest that sensorimotor asymmetries in dynamic coordination might explain limb choices. We discuss the implications of these results for theories of action selection, models of handedness, and models of neural lateralization.

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Garny, H., G. E. Bodeker, D. Smale, M. Dameris et V. Grewe. « Drivers of hemispheric differences in return dates of mid-latitude stratospheric ozone to historical levels ». Atmospheric Chemistry and Physics 13, n^o 15 (1 août 2013) : 7279–300. http://dx.doi.org/10.5194/acp-13-7279-2013.

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Abstract. Chemistry-climate models (CCMs) project an earlier return of northern mid-latitude total column ozone to 1980 values compared to the southern mid-latitudes. The chemical and dynamical drivers of this hemispheric difference are investigated in this study. The hemispheric asymmetry in return dates is a robust result across different CCMs and is qualitatively independent of the method used to estimate return dates. However, the differences in dates of return to 1980 levels between the southern and northern mid-latitudes can vary between 0 and 30 yr across the range of CCM projections analyzed. Positive linear trends in ozone lead to an earlier return of ozone than expected from the return of Cly to 1980 levels. This forward shift is stronger in the Northern than in the Southern Hemisphere because (i) trends have a larger effect on return dates if the sensitivity of ozone to Cly is lower and (ii) the trends in the Northern Hemisphere are stronger than in the Southern Hemisphere. An attribution analysis performed with two CCMs shows that chemically-induced changes in ozone are the major driver of the earlier return of ozone to 1980 levels in northern mid-latitudes; therefore transport changes are of minor importance. This conclusion is supported by the fact that the spread in the simulated hemispheric difference in return dates across an ensemble of twelve models is only weakly related to the spread in the simulated hemispheric asymmetry of trends in the strength of the Brewer–Dobson circulation. The causes for chemically-induced asymmetric ozone trends relevant for the total column ozone return date differences are found to be (i) stronger increases in ozone production due to enhanced NOx concentrations in the Northern Hemisphere lowermost stratosphere and troposphere, (ii) stronger decreases in the destruction rates of ozone by the NOx cycle in the Northern Hemisphere lower stratosphere linked to effects of dynamics and temperature on NOx concentrations, and (iii) an increasing efficiency of heterogeneous ozone destruction by Cly in the Southern Hemisphere mid-latitudes as a~result of decreasing lower stratospheric temperatures.

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Garny, H., G. E. Bodeker, D. Smale, M. Dameris et V. Grewe. « Drivers of hemispheric differences in return dates of mid-latitude stratospheric ozone to historical levels ». Atmospheric Chemistry and Physics Discussions 12, n^o 12 (19 décembre 2012) : 32825–81. http://dx.doi.org/10.5194/acpd-12-32825-2012.

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Abstract. Chemistry-climate models (CCMs) project an earlier return of northern mid-latitude total column ozone to 1980 values compared to the southern mid-latitudes. The chemical and dynamical drivers of this hemispheric difference are investigated in this study. The hemispheric asymmetry in return dates is a robust result across different CCMs and is qualitatively independent of the method used to estimate return dates. However, the differences in dates of return to 1980 levels between the southern and northern mid-latitudes can vary between 0 and 30 yr across the range of CCM projections analyzed. An attribution analysis performed with two CCMs shows that chemically-induced changes in ozone are the major driver of the earlier return of ozone to 1980 levels in northern mid-latitudes; transport changes are of minor importance. This conclusion is supported by the fact that the spread in the simulated hemispheric difference in return dates across an ensemble of twelve models is only weakly related to the spread in the simulated hemispheric asymmetry of trends in the strength of the Brewer–Dobson circulation. The causes for chemically-induced asymmetric ozone trends relevant for the total column ozone return date differences are found to be (i) stronger increases in ozone production due to enhanced NOx concentrations in the Northern Hemisphere lowermost stratosphere and troposphere, (ii) stronger decreases in the destruction rates of ozone by the NOx cycle in the Northern Hemisphere lower stratosphere linked to effects of dynamics and temperature on NOx concentrations and (iii) an increasing efficiency of heterogeneous ozone destruction by Cly in the Southern Hemisphere mid-latitudes as a result of decreasing temperatures.

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Knolle, Lawrence, Harold W. Gordon et Danjuma Gwany. « Relationship between Performance and Preference Measures of Cognitive Laterality ». Psychological Reports 61, n^o 1 (août 1987) : 215–23. http://dx.doi.org/10.2466/pr0.1987.61.1.215.

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This study examined the relationship between two methods of assessing cognitive laterality, one by responses on a preference inventory and the other by assessing asymmetry of hemispheric performance on tests associated with processing in the left or right cerebral hemispheres. 87 graduate students were administered both instruments. Analysis showed negative or no relations between the preference and performance measures. The performance tests associated with left- and right-hemisphere functions were taken directly or adapted from tests showing left- or right-hemisphere superiority in unilateral lesioned patients, brain-divided patients, and normal subjects. The preference inventories were constructed on the basis of the same research but have not been validly related to brain functions. The results of this study suggest that the two types of instruments do not measure the same thing.

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Lekshmi, B., Dibyendu Nandy et H. M. Antia. « Hemispheric asymmetry in meridional flow and the sunspot cycle ». Monthly Notices of the Royal Astronomical Society 489, n^o 1 (8 août 2019) : 714–22. http://dx.doi.org/10.1093/mnras/stz2168.

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ABSTRACT Magnetohydrodynamic dynamo modelling shows that the large-scale solar meridional plasma flow plays an important role in governing the dynamics of the sunspot cycle. Observations indicate that meridional flow velocities at each solar latitude and depth vary over time and are asymmetric across the equator. Here, using helioseismic observations we explore the temporal variation in the hemispherical asymmetry of near-surface residual (time-varying) component of the Sun’s meridional flow velocity. The meridional flow velocities obtained from Global Oscillation Network Group (GONG) and Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO) ring-diagram pipelines are used in this work. Our data set covers the declining phase of cycle 23 and cycle 24 (from July 2001 till December 2018) and the flow velocities are poleward for the observed depth range. We observe a time delayed anticorrelation between the hemispherical asymmetry in near-surface meridional flow velocities and the sunspot cycle quantified in terms of magnetic flux and sunspot number. Interestingly, asymmetry in meridional flow velocity precedes the asymmetry in sunspot cycle by 3.1–3.5 yr. We propose that meridional flow asymmetry is a precursor of asymmetry in hemispherical cycle strength. The symmetric component of meridional flow is observed to be positively correlated with the corresponding symmetric components of the magnetic cycle, also with a time delay. Our analysis sets important constraints on theories for the origin of meridional plasma flow asymmetries and its temporal variations and is relevant for understanding the role of plasma flux transport processes in determining hemispheric asymmetry in the sunspot cycle.

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Novikova, Galina Albertovna, et Andrey Gorgonyevich Solovyev. « FUNCTIONAL ASYMMETRY OF BRAIN HEMISPHERES IN ALCOHOL DEPENDENCE ». Reviews on Clinical Pharmacology and Drug Therapy 10, n^o 3 (15 septembre 2012) : 13–17. http://dx.doi.org/10.17816/rcf10313-17.

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With the goal to study peculiarities of functional asymmetry of the brain hemispheres in alcohol dependence, there has been done an analysis of current research data from Russian and foreign studies. It has been shown that alcohol is a neurochemical modulator of interhemispheric relations, it affects functional asymmetry of the brain hemispheres, perception processes, changes emotional background, influences motor asymmetry, the brain cortex functional activity. Alcohol intoxication is described by the right hemisphere lateralization and a laterodeviation of the brain hemispheres’ functional asymmetry to the left hemisphere. Studies of adolescents with beer alcoholization have shown left sided laterodeviation of functional asymmetry with dominating left-sided lateralization of motor signs, increased delta activity of the brain biorhythms. The received data indicate a substantial breach of functional asymmetry in alcohol users, in what connection the breach involve the motor and sensory levels.

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St. Jacques, Peggy, David C. Rubin, Kevin S. LaBar et Roberto Cabeza. « The Short and Long of It : Neural Correlates of Temporal-order Memory for Autobiographical Events ». Journal of Cognitive Neuroscience 20, n^o 7 (juillet 2008) : 1327–41. http://dx.doi.org/10.1162/jocn.2008.20091.

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Previous functional neuroimaging studies of temporal-order memory have investigated memory for laboratory stimuli that are causally unrelated and poor in sensory detail. In contrast, the present functional magnetic resonance imaging (fMRI) study investigated temporal-order memory for autobiographical events that were causally interconnected and rich in sensory detail. Participants took photographs at many campus locations over a period of several hours, and the following day they were scanned while making temporal-order judgments to pairs of photographs from different locations. By manipulating the temporal lag between the two locations in each trial, we compared the neural correlates associated with reconstruction processes, which we hypothesized depended on recollection and contribute mainly to short lags, and distance processes, which we hypothesized to depend on familiarity and contribute mainly to longer lags. Consistent with our hypotheses, parametric fMRI analyses linked shorter lags to activations in regions previously associated with recollection (left prefrontal, parahippocampal, precuneus, and visual cortices), and longer lags with regions previously associated with familiarity (right prefrontal cortex). The hemispheric asymmetry in prefrontal cortex activity fits very well with evidence and theories regarding the contributions of the left versus right prefrontal cortex to memory (recollection vs. familiarity processes) and cognition (systematic vs. heuristic processes). In sum, using a novel photo-paradigm, this study provided the first evidence regarding the neural correlates of temporal-order for autobiographical events.

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Braun, Claude M. J., Mathieu Dumont, Julie Duval, Isabelle Hamel et Lucie Godbout. « Opposed Left and Right Brain Hemisphere Contributions to Sexual Drive : A Multiple Lesion Case Analysis ». Behavioural Neurology 14, n^o 1-2 (2003) : 55–61. http://dx.doi.org/10.1155/2003/123757.

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Brain topographical studies of normal men have have shown that sexual excitation is asymmetric in the brain hemispheres. Group studies of patients with unilateral epileptic foci and other studies of patients with unilateral brain lesions have come to the same conclusion. The present study reviewed previously published single case reports of patients with frank hypo or hypersexuality subsequent to a unilateral brain lesion. Hyposexual patients tended to have left hemisphere lesions (primarily of the temporal lobe), and hypersexual patients tended to have right hemisphere lesions (primarily of the temporal lobe) (p< 0.05). We interpret this double dissociation as part of a more general phenomenon of psychic tone similarly dissociated with regard to hemispheric control, including mood, psychomotor baseline, speech rate, and even immunity. The behavioral significance of this psychic tone is to modulate approach versus avoidance behavior.

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Сеинова et L. Seinova. « A comparative analysis of cerebral asymmetry according to data from perfusion computed tomography in infarctions of the cerebral hemispheres and dyscirculatory encephalopathy ». Journal of New Medical Technologies. eJournal 9, n^o 4 (8 décembre 2015) : 0. http://dx.doi.org/10.12737/16770.

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Currently a problem of timely diagnostics and treatment of disorders of cerebral circulation is one of the most important for medicine, as strokes and chronic brain ischemia occupy a significant place among the diseases leading to mortality and disability of population. Computed tomography is one of the leading diagnostics of cerebro-vascular disorders. Today, the diagnostic capabilities of perfusion computed tomography, especially in the field of subtle changes in perfusion in infected and in the contralateral hemispheres of the brain are poorly understood and aren’t used in full. The relevance and scientific novelty of this research is not in doubt. Based on the data of 87 patients with ischemic infarction of the cerebral hemispheres of the brain and vascular encephalopathy, a comparative analysis of blood flow in the affected and contralateral hemispheres, was carried out. The degree of asymmetry of blood flow depending on the phase of development of ischemic stroke and chronic brain ischemia was evaluated. The studies have shown that the relative indicator of inter-hemispheric asymmetry is reduced in the course of development of cerebral infarction, reaching minimum values of dyscirculatory encephalopathy. The author substantiates the practical use of the proposed indicator of inter-hemispheric asymmetry in the evaluation of the degree of chronic ischemic disturbances of cerebral blood flow.

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Van Essen, David C., Chad J. Donahue, Timothy S. Coalson, Henry Kennedy, Takuya Hayashi et Matthew F. Glasser. « Cerebral cortical folding, parcellation, and connectivity in humans, nonhuman primates, and mice ». Proceedings of the National Academy of Sciences 116, n^o 52 (23 décembre 2019) : 26173–80. http://dx.doi.org/10.1073/pnas.1902299116.

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Advances in neuroimaging and neuroanatomy have yielded major insights concerning fundamental principles of cortical organization and evolution, thus speaking to how well different species serve as models for human brain function in health and disease. Here, we focus on cortical folding, parcellation, and connectivity in mice, marmosets, macaques, and humans. Cortical folding patterns vary dramatically across species, and individual variability in cortical folding increases with cortical surface area. Such issues are best analyzed using surface-based approaches that respect the topology of the cortical sheet. Many aspects of cortical organization can be revealed using 1 type of information (modality) at a time, such as maps of cortical myelin content. However, accurate delineation of the entire mosaic of cortical areas requires a multimodal approach using information about function, architecture, connectivity, and topographic organization. Comparisons across the 4 aforementioned species reveal dramatic differences in the total number and arrangement of cortical areas, particularly between rodents and primates. Hemispheric variability and bilateral asymmetry are most pronounced in humans, which we evaluated using a high-quality multimodal parcellation of hundreds of individuals. Asymmetries include modest differences in areal size but not in areal identity. Analyses of cortical connectivity using anatomical tracers reveal highly distributed connectivity and a wide range of connection weights in monkeys and mice; indirect measures using functional MRI suggest a similar pattern in humans. Altogether, a multifaceted but integrated approach to exploring cortical organization in primate and nonprimate species provides complementary advantages and perspectives.

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PREDA, Vasile Radu. « Cerebral Hemispheric Dominance and Lateralization. Examination methods and procedures ». Revista Română de Terapia Tulburărilor de Limbaj şi Comunicare VII, n^o 2 (31 octobre 2021) : 67–84. http://dx.doi.org/10.26744/rrttlc.2021.7.2.07.

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On the basis of electrophysiological and neuropsychological investigations the existence of cerebral hemispheric dominance has been established. Thus, a certain psycho-behavioural function may not be equally governed by either the left or the right hemisphere, a tendency towards lateralization coming into play (Sperri, 1974; Arseni, Golu, Dănăilă, 1983; Funnell, Carballis, Gazzanga, 2000). The functional asymmetry of the analysers is encountered both at the peripheral level, through the sensory-motor lateralization of paired receptors, and at the cortical level, through the asymmetrical functioning of the cerebral hemispheres. Consequently, tests for hemispheric dominance, as well as tests for lateralization must, respectively, be employed. When examining cerebral hemispheric dominance and lateralization, the characteristics of the organs under investigation are taken into account, and so is the age of the subjects. The examination of functional asymmetry in the case of analyzers with paired receptors has relied on an impressive number of trials, procedures, tests and questionnaires on lateralization, all suitable for the subjects’ age and for the psycho-physiological characteristics of the respective couple of paired organs. The combined use of lateralization tests specifically adapted for all paired organs (hand, eye, is essential in order to establish the degree of lateralization homogeneity. The examinations and the calculation of the laterality index are to be done periodically, the results being recorded in a chart that reflects the evolution of lateralization as a result of engaging the child in various activities meant for a specific type of lateralization.

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Krol, Maarten, Marco de Bruine, Lars Killaars, Huug Ouwersloot, Andrea Pozzer, Yi Yin, Frederic Chevallier et al. « Age of air as a diagnostic for transport timescales in global models ». Geoscientific Model Development 11, n^o 8 (3 août 2018) : 3109–30. http://dx.doi.org/10.5194/gmd-11-3109-2018.

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Abstract. This paper presents the first results of an age-of-air (AoA) inter-comparison of six global transport models. Following a protocol, three global circulation models and three chemistry transport models simulated five tracers with boundary conditions that grow linearly in time. This allows for an evaluation of the AoA and transport times associated with inter-hemispheric transport, vertical mixing in the troposphere, transport to and in the stratosphere, and transport of air masses between land and ocean. Since AoA is not a directly measurable quantity in the atmosphere, simulations of 222Rn and SF6 were also performed. We focus this first analysis on averages over the period 2000–2010, taken from longer simulations covering the period 1988–2014. We find that two models, NIES and TOMCAT, show substantially slower vertical mixing in the troposphere compared to other models (LMDZ, TM5, EMAC, and ACTM). However, while the TOMCAT model, as used here, has slow transport between the hemispheres and between the atmosphere over land and ocean, the NIES model shows efficient horizontal mixing and a smaller latitudinal gradient in SF6 compared to the other models and observations. We find consistent differences between models concerning vertical mixing of the troposphere, expressed as AoA differences and modelled 222Rn gradients between 950 and 500 hPa. All models agree, however, on an interesting asymmetry in inter-hemispheric mixing, with faster transport from the Northern Hemisphere surface to the Southern Hemisphere than vice versa. This is attributed to a rectifier effect caused by a stronger seasonal cycle in boundary layer venting over Northern Hemispheric land masses, and possibly to a related asymmetric position of the intertropical convergence zone. The calculated AoA in the mid–upper stratosphere varies considerably among the models (4–7 years). Finally, we find that the inter-model differences are generally larger than differences in AoA that result from using the same model with a different resolution or convective parameterisation. Taken together, the AoA model inter-comparison provides a useful addition to traditional approaches to evaluate transport timescales. Results highlight that inter-model differences associated with resolved transport (advection, reanalysis data, nudging) and parameterised transport (convection, boundary layer mixing) are still large and require further analysis. For this purpose, all model output and analysis software are available.

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Ikkert, Oksana, et Tetiana Korol. « CEREBRAL HEMISPHERES FUNCTIONAL ASYMMETRY IN THE EDUCATION OF NATURAL SPECIALTIES AND HUMANITIES STUDENTS ». Scientific Journal of Polonia University 58, n^o 3 (1 septembre 2023) : 90–97. http://dx.doi.org/10.23856/5813.

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The functional asymmetry of the human brain hemispheres (motor, sensory and mental) reflects the difference in the distribution of neuropsychological functions between its right and left hemispheres. Both hemispheres are involved in the implementation of any types of mental activity or regulation of vegetative physiological processes, but each of them provides different aspects of this activity and some processes domination. Persons with left-hemisphere and right-hemisphere thinking differ in the features of perception, analysis, and reproduction of information, which is important in the process of students' educational activities. That is why the aim of this investigation was to conduct a comparative analysis of the types of the brain hemispheres dominance in students of natural and humanities education who study at the biological and philosophical faculties of the Ivan Franko National University of Lviv and proposed methodological approaches for development and activation both (left and right) brain hemispheres. Methods used in the study: determining the coefficient of functional asymmetry of the brain; general scientific (analysis and synthesis), methods of theoretical research (from abstract to concrete). It was shown that most of the student are dominated by the left brain hemisphere but organizing of the educational process needs to use methods of educational activities aimed at the development and activation both (left and right) brain hemispheres.

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Hayes, Scott M., Elsa Baena, Trong-Kha Truong et Roberto Cabeza. « Neural Mechanisms of Context Effects on Face Recognition : Automatic Binding and Context Shift Decrements ». Journal of Cognitive Neuroscience 22, n^o 11 (novembre 2010) : 2541–54. http://dx.doi.org/10.1162/jocn.2009.21379.

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Although people do not normally try to remember associations between faces and physical contexts, these associations are established automatically, as indicated by the difficulty of recognizing familiar faces in different contexts (“butcher-on-the-bus” phenomenon). The present fMRI study investigated the automatic binding of faces and scenes. In the face–face (F–F) condition, faces were presented alone during both encoding and retrieval, whereas in the face/scene–face (FS–F) condition, they were presented overlaid on scenes during encoding but alone during retrieval (context change). Although participants were instructed to focus only on the faces during both encoding and retrieval, recognition performance was worse in the FS–F than in the F–F condition (“context shift decrement” [CSD]), confirming automatic face–scene binding during encoding. This binding was mediated by the hippocampus as indicated by greater subsequent memory effects (remembered > forgotten) in this region for the FS–F than the F–F condition. Scene memory was mediated by right parahippocampal cortex, which was reactivated during successful retrieval when the faces were associated with a scene during encoding (FS–F condition). Analyses using the CSD as a regressor yielded a clear hemispheric asymmetry in medial temporal lobe activity during encoding: Left hippocampal and parahippocampal activity was associated with a smaller CSD, indicating more flexible memory representations immune to context changes, whereas right hippocampal/rhinal activity was associated with a larger CSD, indicating less flexible representations sensitive to context change. Taken together, the results clarify the neural mechanisms of context effects on face recognition.

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Eckert, Mark A., Kenneth I. Vaden et Federico Iuricich. « Cortical asymmetries at different spatial hierarchies relate to phonological processing ability ». PLOS Biology 20, n^o 4 (5 avril 2022) : e3001591. http://dx.doi.org/10.1371/journal.pbio.3001591.

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The ability to map speech sounds to corresponding letters is critical for establishing proficient reading. People vary in this phonological processing ability, which has been hypothesized to result from variation in hemispheric asymmetries within brain regions that support language. A cerebral lateralization hypothesis predicts that more asymmetric brain structures facilitate the development of foundational reading skills like phonological processing. That is, structural asymmetries are predicted to linearly increase with ability. In contrast, a canalization hypothesis predicts that asymmetries constrain behavioral performance within a normal range. That is, structural asymmetries are predicted to quadratically relate to phonological processing, with average phonological processing occurring in people with the most asymmetric structures. These predictions were examined in relatively large samples of children (N = 424) and adults (N = 300), using a topological asymmetry analysis of T1-weighted brain images and a decoding measure of phonological processing. There was limited evidence of structural asymmetry and phonological decoding associations in classic language-related brain regions. However, and in modest support of the cerebral lateralization hypothesis, small to medium effect sizes were observed where phonological decoding accuracy increased with the magnitude of the largest structural asymmetry across left hemisphere cortical regions, but not right hemisphere cortical regions, for both the adult and pediatric samples. In support of the canalization hypothesis, small to medium effect sizes were observed where phonological decoding in the normal range was associated with increased asymmetries in specific cortical regions for both the adult and pediatric samples, which included performance monitoring and motor planning brain regions that contribute to oral and written language functions. Thus, the relevance of each hypothesis to phonological decoding may depend on the scale of brain organization.

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Chiou, E. W., L. W. Thomason et W. P. Chu. « Variability of Stratospheric Water Vapor Inferred from SAGE II, HALOE, and Boulder (Colorado) Balloon Measurements ». Journal of Climate 19, n^o 16 (15 août 2006) : 4121–33. http://dx.doi.org/10.1175/jcli3841.1.

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Abstract The variability of stratospheric water vapor between 1996 and 2004 has been studied using multiyear measurements from the Stratospheric Aerosol and Gas Experiment II (SAGE II) version 6.2 dataset, the Halogen Occultation Experiment (HALOE) version 19 dataset, and the balloon-borne frost point hygrometer data record at Boulder, Colorado (40°N, 105°W). The features derived from SAGE II and HALOE for 20° latitudinal zones from 60°S to 60°N at various altitudes (16–34 km) show good quantitative agreement regarding the phases and magnitudes of annual, semiannual, and quasi-biennial oscillations (QBO). For the latitudinal zones 20°–40° and 40°–60°, the hemispheric asymmetry at 22 km with mainly QBO in the north and predominantly annual oscillations in the south has been revealed by both SAGE II and HALOE observations. Strong correlation exists between SAGE II and HALOE lower-stratospheric H2O anomalies over low latitudes and 100-hPa tropical zonal mean temperature anomalies. The correlation coefficients based on the 0°–20°S water vapor time series with H2O lagged by 2 months are 0.81 and 0.70 for HALOE and SAGE II, respectively. For 35°–45°N, SAGE II and HALOE show consistent trends generally varying from −0.05 to −0.02 ppmv yr−1 between 16 and 34 km. The corresponding analyses based on frost point measurements over Boulder show insignificant trends. These trends are not strongly dependent on the end points of the analysis and stand in contrast to the positive trends reported in previous studies that include data records prior to 1994. For the lower stratosphere, investigations of the entire balloon-borne dataset over Boulder indicate higher values of mixing ratios after 1992–93 compared to the period 1980–92. In contrast, SAGE II monthly zonal mean measurements for 35°–45°N show insignificant differences between the periods 1987–89 and 1996–2004.

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Nicholls, Michael E. R. « Hemispheric Asymmetries for Temporal Resolution : A Signal Detection Analysis of Threshold and Bias ». Quarterly Journal of Experimental Psychology Section A 47, n^o 2 (mai 1994) : 291–310. http://dx.doi.org/10.1080/14640749408401113.

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Divided visual field techniques were used to investigate hemispheric asymmetries for (a) the threshold of fusion of two flashes of light and (b) the detection of simultaneous versus successive events for a group of normal, right-handed adults. A signal detection analysis revealed a higher level of accuracy for the right visual field-left hemisphere (RVF-LH) relative to the left visual field-right hemisphere (LVF-RH) for both tasks. These results were interpreted in terms of a general left-hemisphere advantage for the discrimination of fine temporal events. The implications of these results for models of temporary asymmetry that describe the left hemisphere's advantage in terms of an exclusive specialization or relative superiority are then discussed.

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Kolennikova, Maria, et Daria Gushchina. « Revisiting the Contrasting Response of Polar Stratosphere to the Eastern and Central Pacific El Niños ». Atmosphere 13, n^o 5 (24 avril 2022) : 682. http://dx.doi.org/10.3390/atmos13050682.

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El Niño Southern Oscillation (ENSO) invokes the release of a large amount of heat and moisture into the tropical atmosphere, inducing circulation anomalies. The circulation response to ENSO propagates both horizontally poleward and vertically into the stratosphere. Here, we investigate the remote response of the polar stratosphere to ENSO using reanalysis data, along with composite and regression analysis. In particular, we focus on inter-event variability resulting from two ENSO types (the Eastern Pacific (EP) and the Central Pacific (CP) El Niño) and the inter-hemispheric difference in the ENSO responses. Consistent with previous results, we show that ENSO is associated with a weakening in the stratospheric polar vortex but emphasize that the polar stratosphere response strongly depends on the ENSO types, differs between the hemispheres, and changes from the lower to middle stratosphere. The main inter-hemispheric asymmetry manifests in response to the EP El Niño, which is not significant in the Southern Hemisphere, while CP events are associated with pronounced weakening in the polar vortex in both hemispheres. The weakening in the stratospheric polar vortex arguably results from the intensification in the wave flux from the troposphere into the stratosphere and is accompanied by increased heat transport. The latter causes stratospheric warming in the Artic and Antarctic and slows zonal currents. The response of the lower stratosphere circulation to ENSO is approximately the opposite to that of the middle stratosphere.

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Kolennikova, Maria, et Daria Gushchina. « Revisiting the Contrasting Response of Polar Stratosphere to the Eastern and Central Pacific El Niños ». Atmosphere 13, n^o 5 (24 avril 2022) : 682. http://dx.doi.org/10.3390/atmos13050682.

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El Niño Southern Oscillation (ENSO) invokes the release of a large amount of heat and moisture into the tropical atmosphere, inducing circulation anomalies. The circulation response to ENSO propagates both horizontally poleward and vertically into the stratosphere. Here, we investigate the remote response of the polar stratosphere to ENSO using reanalysis data, along with composite and regression analysis. In particular, we focus on inter-event variability resulting from two ENSO types (the Eastern Pacific (EP) and the Central Pacific (CP) El Niño) and the inter-hemispheric difference in the ENSO responses. Consistent with previous results, we show that ENSO is associated with a weakening in the stratospheric polar vortex but emphasize that the polar stratosphere response strongly depends on the ENSO types, differs between the hemispheres, and changes from the lower to middle stratosphere. The main inter-hemispheric asymmetry manifests in response to the EP El Niño, which is not significant in the Southern Hemisphere, while CP events are associated with pronounced weakening in the polar vortex in both hemispheres. The weakening in the stratospheric polar vortex arguably results from the intensification in the wave flux from the troposphere into the stratosphere and is accompanied by increased heat transport. The latter causes stratospheric warming in the Artic and Antarctic and slows zonal currents. The response of the lower stratosphere circulation to ENSO is approximately the opposite to that of the middle stratosphere.

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Pinel, Philippe, et Stanislas Dehaene. « Beyond Hemispheric Dominance : Brain Regions Underlying the Joint Lateralization of Language and Arithmetic to the Left Hemisphere ». Journal of Cognitive Neuroscience 22, n^o 1 (janvier 2010) : 48–66. http://dx.doi.org/10.1162/jocn.2009.21184.

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Language and arithmetic are both lateralized to the left hemisphere in the majority of right-handed adults. Yet, does this similar lateralization reflect a single overall constraint of brain organization, such an overall “dominance” of the left hemisphere for all linguistic and symbolic operations? Is it related to the lateralization of specific cerebral subregions? Or is it merely coincidental? To shed light on this issue, we performed a “colateralization analysis” over 209 healthy subjects: We investigated whether normal variations in the degree of left hemispheric asymmetry in areas involved in sentence listening and reading are mirrored in the asymmetry of areas involved in mental arithmetic. Within the language network, a region-of-interest analysis disclosed partially dissociated patterns of lateralization, inconsistent with an overall “dominance” model. Only two of these areas presented a lateralization during sentence listening and reading which correlated strongly with the lateralization of two regions active during calculation. Specifically, the profile of asymmetry in the posterior superior temporal sulcus during sentence processing covaried with the asymmetry of calculation-induced activation in the intraparietal sulcus, and a similar colateralization linked the middle frontal gyrus with the superior posterior parietal lobule. Given recent neuroimaging results suggesting a late emergence of hemispheric asymmetries for symbolic arithmetic during childhood, we speculate that these colateralizations might constitute developmental traces of how the acquisition of linguistic symbols affects the cerebral organization of the arithmetic network.

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Zhu, Yue, Shuai Wang, Xiaohong Gong, Elliot K. Edmiston, Suyu Zhong, Chao Li, Pengfei Zhao et al. « Associations between hemispheric asymmetry and schizophrenia-related risk genes in people with schizophrenia and people at a genetic high risk of schizophrenia ». British Journal of Psychiatry 219, n^o 1 (30 avril 2021) : 392–400. http://dx.doi.org/10.1192/bjp.2021.47.

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BackgroundSchizophrenia is considered a polygenic disorder. People with schizophrenia and those with genetic high risk of schizophrenia (GHR) have presented with similar neurodevelopmental deficits in hemispheric asymmetry. The potential associations between neurodevelopmental abnormalities and schizophrenia-related risk genes in both schizophrenia and those with GHR remains unclear.AimsTo investigate the shared and specific alternations to the structural network in people with schizophrenia and those with GHR. And to identify an association between vulnerable structural network alternation and schizophrenia-related risk genes.MethodA total of 97 participants with schizophrenia, 79 participants with GHR and 192 healthy controls, underwent diffusion tensor imaging (DTI) scans at a single site. We used graph theory to characterise hemispheric and whole-brain structural network topological metrics. For 26 people in the schizophrenia group and 48 in the GHR group with DTI scans we also calculated their schizophrenia-related polygenic risk scores (SZ-PRSs). The correlations between alterations to the structural network and SZ-PRSs were calculated. Based on the identified genetic–neural association, bioinformatics enrichment was explored.ResultsThere were significant hemispheric asymmetric deficits of nodal efficiency, global and local efficiency in the schizophrenia and GHR groups. Hemispheric asymmetric deficit of local efficiency was significantly positively correlated with SZ-PRSs in the schizophrenia and GHR groups. Bioinformatics enrichment analysis showed that these risk genes may be linked to signal transduction, neural development and neuron structure. The schizophrenia group showed a significant decrease in the whole-brain structural network.ConclusionsThe shared asymmetric deficits in people with schizophrenia and those with GHR, and the association between anomalous asymmetry and SZ-PRSs suggested a vulnerability imaging marker regulated by schizophrenia-related risk genes. Our findings provide new insights into asymmetry regulated by risk genes and provides a better understanding of the genetic–neural pathological underpinnings of schizophrenia.

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Kong, Xiang-Zhen, Samuel R. Mathias, Tulio Guadalupe, David C. Glahn, Barbara Franke, Fabrice Crivello, Nathalie Tzourio-Mazoyer, Simon E. Fisher, Paul M. Thompson et Clyde Francks. « Mapping cortical brain asymmetry in 17,141 healthy individuals worldwide via the ENIGMA Consortium ». Proceedings of the National Academy of Sciences 115, n^o 22 (15 mai 2018) : E5154—E5163. http://dx.doi.org/10.1073/pnas.1718418115.

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Hemispheric asymmetry is a cardinal feature of human brain organization. Altered brain asymmetry has also been linked to some cognitive and neuropsychiatric disorders. Here, the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium presents the largest-ever analysis of cerebral cortical asymmetry and its variability across individuals. Cortical thickness and surface area were assessed in MRI scans of 17,141 healthy individuals from 99 datasets worldwide. Results revealed widespread asymmetries at both hemispheric and regional levels, with a generally thicker cortex but smaller surface area in the left hemisphere relative to the right. Regionally, asymmetries of cortical thickness and/or surface area were found in the inferior frontal gyrus, transverse temporal gyrus, parahippocampal gyrus, and entorhinal cortex. These regions are involved in lateralized functions, including language and visuospatial processing. In addition to population-level asymmetries, variability in brain asymmetry was related to sex, age, and intracranial volume. Interestingly, we did not find significant associations between asymmetries and handedness. Finally, with two independent pedigree datasets (n = 1,443 and 1,113, respectively), we found several asymmetries showing significant, replicable heritability. The structural asymmetries identified and their variabilities and heritability provide a reference resource for future studies on the genetic basis of brain asymmetry and altered laterality in cognitive, neurological, and psychiatric disorders.

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Kanat, Ayhan, Ugur Yazar, Bulent Ozdemir, Zerrin O. Coskun et Ozlem Erdivanli. « Frontal sinus asymmetry : Is it an effect of cranial asymmetry ? X-ray analysis of 469 normal adult human frontal sinus ». Journal of Neurosciences in Rural Practice 06, n^o 04 (octobre 2015) : 511–14. http://dx.doi.org/10.4103/0976-3147.168436.

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ABSTRACT Background and Aims: There is no study in the literature that investigates an asymmetric morphological feature of the frontal sinus (FS). Materials and Methods: Four hundred and sixty-nine consecutive direct X-rays of FSs were analyzed for the asymmetry between the right and left sides. When an asymmetry in the height and contour of the FS existed, this difference was quantified. Results: Of the 469 patients, X-rays of 402 patients (85.7%), there was an asymmetry between right and left sides of the FS. Of these 235 (50.1%) were dominant on the left side, whereas 167 (35.6%) were dominant on the right, the sinuses of remaining 67 patients (14.3%) was symmetric. Statistical Analysis: The comparisons between parameters were performed using Wilkinson signed rank test. The relationship between handedness and sinus asymmetry was also examined by two proportions test. There is statistically significant difference between the dominance of left and right FS. Conclusions: Hemispheric dominance may have some effect (s) of on sinus asymmetry of the human cranium. Surgeons sometimes enter the cranium through the FS and knowledge of asymmetric FS is important to minimize surgical complications.

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Xiang Qian, Xu, G. V. Korobeynikov, D. M. Mishchuk et L. G. Korobeynikova. « Features of individual cognitive style of qualified badminton players ». Health, sport, rehabilitation 6, n^o 4 (20 décembre 2020) : 39–46. http://dx.doi.org/10.34142/hsr.2020.06.04.04.

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Aim: to determine of peculiarities of personal cognitive styles in qualified badminton players. Material and methods. The studies were carried out using the hardware-software computer complex "Multipsychometer-05". The modified Stroop test was selected. The indicators of the test "Field dependence" were determined: field independence, left hemispheric dominance, functional asymmetry, and the effectiveness of the test. The obtained results of the study were analyzed for the entire sample of badminton players, as well as separately for men and women. Results. According to the results of scientific research on the field dependence of qualified badminton players, it was found that all athletes in our sample demonstrate a slight bias towards field dependence; dominated by right hemisphere dominance; in functional asymmetry and efficiency, qualified badminton players demonstrate an average level. The analysis of test indicators, taking into account gender dimorphism, showed that among men 72% demonstrate a predominance of right hemispheric dominance of varying degrees, 28% have left hemispheric dominance. As for women, 54% demonstrate a predominance of right hemispheric dominance of varying degrees, and 37% demonstrate left hemispheric dominance of varying degrees. Conclusions. Men show a tendency towards better test performance and have more pronounced functional asymmetry. The cognitive style of skilled badminton players determines the strategy of selection and processing of information, problem solving, learning and other types of cognitive activities. Because human cognitive-activity styles are genetically determined and demonstrate a pronounced stability of cognitive-stylistic characteristics in ontogenesis, they can be used as prognostic and diagnostic criteria.

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