scholarly journals Asymmetry in the Central Nervous System: A Clinical Neuroscience Perspective

2021 ◽  
Vol 15 ◽  
Author(s):  
Annakarina Mundorf ◽  
Jutta Peterburs ◽  
Sebastian Ocklenburg
Keyword(s):  
Large Scale ◽  
Right Hemisphere ◽  
Autism Spectrum ◽  
Subcortical Structures ◽  
Clinical Neuroscience ◽  
Brain Areas ◽  
Hemispheric Asymmetries ◽  
The Central Nervous System ◽  
Specific Disorders ◽  
The Right

Recent large-scale neuroimaging studies suggest that most parts of the human brain show structural differences between the left and the right hemisphere. Such structural hemispheric asymmetries have been reported for both cortical and subcortical structures. Interestingly, many neurodevelopmental and psychiatric disorders have been associated with altered functional hemispheric asymmetries. However, findings concerning the relation between structural hemispheric asymmetries and disorders have largely been inconsistent, both within specific disorders as well as between disorders. In the present review, we compare structural asymmetries from a clinical neuroscience perspective across different disorders. We focus especially on recent large-scale neuroimaging studies, to concentrate on replicable effects. With the notable exception of major depressive disorder, all reviewed disorders were associated with distinct patterns of alterations in structural hemispheric asymmetries. While autism spectrum disorder was associated with altered structural hemispheric asymmetries in a broader range of brain areas, most other disorders were linked to more specific alterations in brain areas related to cognitive functions that have been associated with the symptomology of these disorders. The implications of these findings are highlighted in the context of transdiagnostic approaches to psychopathology.

The expressivity dimension of speech is the basis of the expression dimension. Evidence from behavioural and neuroimaging studies

2020 ◽  
Author(s):  
Isabelle Hesling
Keyword(s):  
Language Acquisition ◽  
Experimental Psychology ◽  
Right Hemisphere ◽  
Word List ◽  
Behavioral Experiments ◽  
Brain Areas ◽  
Language Communication ◽  
Neuroimaging Data ◽  
List Processing ◽  
The Right

The modalities of communication are the sum of the expression dimension (linguistics) and the expressivity dimension (prosody), both being equally important in language communication. The expressivity dimension which comes first in the act of speech, is the basis on which phonemes, syllables, words, grammar and morphosyntax, i.e., the expression dimension of speech is superimposed. We will review evidence (1) revealing the importance of prosody in language acquisition and (2) showing that prosody triggers the involvement of specific brain areas dedicated to sentences and word-list processing. To support the first point, we will not only rely on experimental psychology studies conducted in newborns and young children but also on neuroimaging studies that have helped to validate these behavioral experiments. Then, neuroimaging data on adults will allow for concluding that the expressivity dimension of speech modulates both the right hemisphere prosodic areas and the left hemisphere network in charge of the expression dimension

scholarly journals Reduced language lateralization in autism and the broader autism phenotype as assessed with robust individual-subjects analyses

2020 ◽  
Author(s):  
Olessia Jouravlev ◽  
Alexander J.E. Kell ◽  
Zachary Mineroff ◽  
A.J. Haskins ◽  
Dima Ayyash ◽  
...  
Keyword(s):  
Language Processing ◽  
Large Scale ◽  
Right Hemisphere ◽  
Autism Spectrum ◽  
Functional Markers ◽  
Large Set ◽  
Autistic Trait ◽  
Functional Responses ◽  
Individual Subject ◽  
Language Lateralization

AbstractOne of the few replicated functional brain differences between individuals with autism spectrum disorders (ASD) and neurotypical (NT) controls is reduced language lateralization. However, most prior reports relied on comparisons of group-level activation maps or functional markers that had not been validated at the individual-subject level, and/or used tasks that do not isolate language processing from other cognitive processes, complicating interpretation. Furthermore, few prior studies have examined functional responses in other functional networks, as needed to determine the selectivity of the effect. Using fMRI, we compared language lateralization between 28 ASD participants and carefully pairwise-matched controls, with the language regions defined individually with a well-validated language localizer. ASD participants showed less lateralized responses due to stronger right hemisphere activations. Further, this effect did not stem from a ubiquitous reduction in lateralization across the brain: ASD participants did not differ from controls in the lateralization of two other large-scale networks—the Theory of Mind network and the Multiple Demand network. Finally, in an exploratory study, we tested whether reduced language lateralization may also be present in NT individuals with high autistic trait load. Indeed, autistic trait load in a large set of NT participants (n=189) was associated with less lateralized language activations. These results suggest that reduced language lateralization is a robust and spatially selective neural marker of autism, present in individuals with ASD, but also in NT individuals with higher genetic liability for ASD, in line with a continuum model of underlying genetic risk.

Distributed grey and white matter deficits in hyperkinetic disorder: MRI evidence for anatomical abnormality in an attentional network

2001 ◽  
Vol 31 (8) ◽  
pp. 1425-1435 ◽  
Author(s):  
S. OVERMEYER ◽  
E. T. BULLMORE ◽  
J. SUCKLING ◽  
A. SIMMONS ◽  
S. C. R. WILLIAMS ◽  
...  
Keyword(s):  
White Matter ◽  
Basal Ganglia ◽  
Large Scale ◽  
Grey Matter ◽  
Right Hemisphere ◽  
Hyperkinetic Disorder ◽  
Normal Children ◽  
Pyramidal Tracts ◽  
Icd 10 ◽  
The Right

Background. Previous neuroimaging studies of children with attention deficit hyperactivity disorder (ADHD) have demonstrated anatomic and functional abnormalities predominantly in frontal and striatal grey matter. Here we report the use of novel image analysis methods, which do not require prior selection of regions of interest, to characterize distributed morphological deficits of both grey and white matter associated with ADHD.Methods. Eighteen children with a refined phenotype of ADHD, who also met ICD-10 criteria for hyperkinetic disorder (mean age 10·4 years), and 16 normal children (mean age 10·3 years) were compared using magnetic resonance imaging. The groups were matched for handedness, sex, height, weight and head circumference. Morphological differences between groups were estimated by fitting a linear model at each voxel in standard space, applying a threshold to the resulting voxel statistic maps to generate clusters of spatially contiguous suprathreshold voxels, and testing cluster ‘mass’, or the sum of suprathreshold voxel statistics in each 2D cluster, by repeated random resampling of the data.Results. The hyperkinetic children had significant grey matter deficits in right superior frontal gyrus (Brodmann area (BA) 8/9), right posterior cingulate gyrus (BA 30) and the basal ganglia bilaterally (especially right globus pallidus and putamen). They also demonstrated significant central white matter deficits in the left hemisphere anterior to the pyramidal tracts and superior to the basal ganglia.Conclusions. This pattern of spatially distributed grey matter deficit in the right hemisphere is compatible with the hypothesis that ADHD is associated with disruption of a large scale neurocognitive network for attention. The left hemispheric white matter deficits may be due to dysmyelination.

scholarly journals A Brain Mapping Approach to Inspect the Underlying Neural Correlates upon Perceiving Persian Metaphors

2020 ◽  
Author(s):  
Elaheh Yazdani ◽  
Amirsaeid Moloodi ◽  
Zahra Kheradmand ◽  
Ali Mohammad Kamali ◽  
K.S. Rao ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Brain Mapping ◽  
Semantic Processing ◽  
Large Scale ◽  
Figurative Language ◽  
Right Hemisphere ◽  
Mother Tongue ◽  
Abstract Concepts ◽  
Neural Modulation ◽  
The Right

Metaphors are frequently used in our daily life communications to comprehend and convey abstract concepts. Different neuroimaging studies also show a wide neural connection to metaphor perception. This study used a brain mapping setup (quantitative electroencephalography) to examine large-scale brain networks in participants when they were submitted to non-metaphorical sentences as compared to creative and conventional metaphorical phrases. To this end, 20 healthy right-handed individuals with Persian as their mother-tongue language consented to participate in the above language task. Having evaluated the functional connectivity across key cortical hubs, no significant or predominant role of the right hemisphere was observed upon comprehension of the conventional and creative metaphorical phrases. Rather, a wide interhemispheric functional connectivity is proposed to play a key part in the above task. Further understanding about the neural networks involved in the semantic processing of metaphors may potentially open new avenues to neural modulation in patients who find it challenging to comprehend figurative language or abstract metaphorical meanings (e.g. schizophrenics).

scholarly journals Functional cortico-subcortical reorganization after complete hemispheric disconnection for intractable epilepsy

2019 ◽  
Author(s):  
Thomas Blauwblomme ◽  
Athena Demertzi ◽  
Jean-Marc Tacchela ◽  
Ludovic Fillon ◽  
Marie Bourgeois ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Right Hemisphere ◽  
Intractable Epilepsy ◽  
Minimally Conscious State ◽  
Conscious State ◽  
Subcortical Structures ◽  
Drug Resistant Epilepsy ◽  
Classification Probability ◽  
The Right ◽  
Minimally Conscious

AbstractHemispherotomy is a treatment for drug-resistant epilepsy with the whole hemisphere involved in seizure onset. As recovery mechanisms are still debated, we characterize functional reorganization with multimodal MRI in two children operated on the right hemisphere (RH). We found that interhemispheric functional connectivity was abolished in both patients. The healthy left hemispheres (LH) displayed focal hyperperfusion in motor and limbic areas, and preserved network-level organization. The disconnected RHs were hypoperfused despite sustained network-level organization. Functional connectivity was increased in the left thalamo-cortical loop and between the cerebelli. The classification probability of the RH corresponding to a minimally conscious state was smaller than for the LH. We conclude that after hemispherotomy, neurological rehabilitation is sustained by cortical disinhibition and reinforcement of connectivity driven by subcortical structures in the remaining hemisphere. Our results highlight the effect of vascularization on functional connectivity and raise inquiries about the conscious state of the isolated hemisphere.

scholarly journals Virtual reality-based sensorimotor adaptation shapes subsequent spontaneous and naturalistic stimulus-driven brain activity

2021 ◽  
Author(s):  
Meytal Wilf ◽  
Celine Dupuis ◽  
Davide Nardo ◽  
Diana Huber ◽  
Sibilla Sander ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Large Scale ◽  
Right Hemisphere ◽  
Functional Neuroimaging ◽  
Brain Activity ◽  
Visual Response ◽  
Spatial Shift ◽  
Before And After ◽  
Behavioural Tests ◽  
The Right

Our everyday life summons numerous novel sensorimotor experiences, to which our brain needs to adapt in order to function properly. However, tracking plasticity of naturalistic behaviour and associated brain modulations is challenging. Here we tackled this question implementing a prism adaptation training in virtual reality (VRPA) in combination with functional neuroimaging. Three groups of healthy participants (N=45) underwent VRPA (with a spatial shift either to the left/right side, or with no shift), and performed fMRI sessions before and after training. To capture modulations in free-flowing, task-free brain activity, the fMRI sessions included resting state and free viewing of naturalistic videos. We found significant decreases in spontaneous functional connectivity between large-scale cortical networks, namely attentional and default mode/fronto-parietal networks, only for adaptation groups. Additionally, VRPA was found to bias visual representations of naturalistic videos, as following rightward adaptation, we found upregulation of visual response in an area in the parieto-occipital sulcus (POS) in the right hemisphere. Notably, the extent of POS upregulation correlated with the size of the VRPA induced after-effect measured in behavioural tests. This study demonstrates that a brief VRPA exposure is able to change large-scale cortical connectivity and correspondingly bias the representation of naturalistic sensory inputs.

scholarly journals Left hemispheric deficit in the sustained neuromagnetic response to periodic click trains in children with ASD.

2020 ◽  
Author(s):  
Tatiana A Stroganova ◽  
Kirill S Komarov ◽  
Olga V Sysoeva ◽  
Dzerasa E Goiaeva ◽  
Tatiana S Obukhova ◽  
...  
Keyword(s):  
Right Hemisphere ◽  
Autism Spectrum ◽  
Neural Basis ◽  
Autism Symptoms ◽  
Language Abilities ◽  
Pitch Processing ◽  
Children With Asd ◽  
Vocal Pitch ◽  
Auditory Response ◽  
The Right

Abstract Background: Deficits in perception and production of vocal pitch are often observed in people with autism spectrum disorder (ASD), but the neural basis of these abnormalities is unknown. In magnetoencephalogram (MEG), spectrally complex periodic sounds trigger two continuous neural responses – the auditory steady state response (ASSR) and the sustained field (SF). It has been shown that the SF in neurotypical individuals is associated with low-level analysis of pitch in the ‘pitch processing center’ of the Heschl’s gyrus. Therefore, this auditory response may reflect vocal pitch processing abnormalities in ASD. The SF, however, has never been studied in people with this disorder. Methods: We used MEG and individual brain models to investigate the ASSR and SF evoked by monaural 40 Hz click trains in boys with ASD (N=35) and neurotypical (NT) boys (N=35) aged 7-12-years.Results: In agreement with the previous research in adults, the cortical sources of the SF in children were located in the left and right Heschl’s gyri, anterolateral to those of the ASSR. In both groups, the SF and ASSR dominated in the right hemisphere and were higher in the hemisphere contralateral to the stimulated ear. The ASSR increased with age in both NT and ASD children and did not differ between the groups. The SF amplitude did not significantly change between the ages of 7 and 12 years. It was moderately attenuated in both hemispheres and was markedly delayed and displaced in the left hemisphere in boys with ASD. The SF delay in participants with ASD was present irrespective of their intelligence level and severity of autism symptoms.Limitations: We did not test the language abilities of our participants. Therefore, the link between SF and processing of vocal pitch in children with ASD remains speculative.Conclusion: Children with ASD demonstrate selective left-hemispheric abnormalities at the level of the core auditory cortex when processing spectrally complex periodic sound. The observed neural deficit may contribute to speech perception difficulties experienced by children with ASD, including their poor perception and production of linguistic prosody.

Of the Right and Left Hand (1646): Sir Thomas Browne's historical survey of ‘handedness”

2005 ◽  
Vol 22 (1) ◽  
pp. 30-32
Author(s):  
Caoimhghin S Breathnach
Keyword(s):  
Left Hemisphere ◽  
Large Scale ◽  
Precise Determination ◽  
Antidepressant Effect ◽  
Hemispheric Asymmetries ◽  
Left Hand ◽  
Left Handedness ◽  
The Right ◽  
Reproducible Manner

‘Handedness’ as an expression of cerebral lateralisation is valuable in analysis of hemispheric asymmetries, carrying implications for implementation (as well as interpretation) of complex cognitive functions. In recent decades it has become possible to categorise handedness in a reproducible manner and, independently, to estimate accurately the degree of language lateralisation of the brain. These advances have re-focussed attention on cerebral organisation and hemispheric asymmetries, and there is now considerable interest in the neuropsychology of left-handedness. Because of procedural and ethical constraints there are relatively few large scale studies on language dominance, whereas handedness has been studied extensively in recent decades. Language is represented in the left hemisphere in all but 1% of right-handers, and in 60% of left-handers; in 15% of right-handers speech representation was bilateral.Precise determination of handedness or lateralisation does not appear to have been assessed in major studies of electroconvulsive therapy (ECT). Results in 29 reports, when the electrodes were placed over either the non-dominant or both hemispheres, were tabulated and briefly discussed by d'Elia and Raotma, but the criterion of lateral dominance assignment was not clearly specified; the unilateral and bilateral placements were equally efficacious in their antidepressant effect. d'Elia, who introduced unilateral therapy in 1970, accepted the assumption that the left hemisphere was ‘dominant’, but later workers were more circumspect.

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