Right Hemisphere Grey Matter Volume and Language Functions in Stroke Aphasia

The role of the right hemisphere (RH) in recovery from aphasia is incompletely understood. The present study quantified RH grey matter (GM) volume in individuals with chronic stroke-induced aphasia and cognitively healthy people using voxel-based morphometry. We compared group differences in GM volume in the entire RH and in RH regions-of-interest. Given that lesion site is a critical source of heterogeneity associated with poststroke language ability, we used voxel-based lesion symptom mapping (VLSM) to examine the relation between lesion site and language performance in the aphasic participants. Finally, using results derived from the VLSM as a covariate, we evaluated the relation between GM volume in the RH and language ability across domains, including comprehension and production processes both at the word and sentence levels and across spoken and written modalities. Between-subject comparisons showed that GM volume in the RH SMA was reduced in the aphasic group compared to the healthy controls. We also found that, for the aphasic group, increased RH volume in the MTG and the SMA was associated with better language comprehension and production scores, respectively. These data suggest that the RH may support functions previously performed by LH regions and have important implications for understanding poststroke reorganization.

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The Role of the Right Hemisphere White Matter Tracts in Chronic Aphasic Patients After Damage of the Language Tracts in the Left Hemisphere

Frontiers in Human Neuroscience ◽

10.3389/fnhum.2021.635750 ◽

2021 ◽

Vol 15 ◽

Author(s):

Evie Kourtidou ◽

Dimitrios Kasselimis ◽

Georgia Angelopoulou ◽

Efstratios Karavasilis ◽

Georgios Velonakis ◽

...

Keyword(s):

White Matter ◽

Left Hemisphere ◽

Right Hemisphere ◽

Diffusion Tensor ◽

Inferior Frontal Gyrus ◽

Language Performance ◽

White Matter Tracts ◽

Post Stroke ◽

Language Functions ◽

The Right

The involvement of the right hemisphere (RH) in language, and especially after aphasia resulting from left hemisphere (LH) lesions, has been recently highlighted. The present study investigates white matter structure in the right hemisphere of 25 chronic post-stroke aphasic patients after LH lesions in comparison with 24 healthy controls, focusing on the four cortico-cortical tracts that link posterior parietal and temporal language-related areas with Broca’s region in the inferior frontal gyrus of the LH: the Superior Longitudinal Fasciculi II and III (SLF II and SLF III), the Arcuate Fasciculus (AF), and the Temporo-Frontal extreme capsule Fasciculus (TFexcF). Additionally, the relationship of these RH white matter tracts to language performance was examined. The patients with post-stroke aphasia in the chronic phase and the healthy control participants underwent diffusion tensor imaging (DTI) examination. The aphasic patients were assessed with standard aphasia tests. The results demonstrated increased axial diffusivity in the RH tracts of the aphasic patients. Patients were then divided according to the extent of the left hemisphere white matter loss. Correlations of language performance with radial diffusivity (RD) in the right hemisphere homologs of the tracts examined were demonstrated for the TFexcF, SLF III, and AF in the subgroup with limited damage to the LH language networks and only with the TFexcF in the subgroup with extensive damage. The results argue in favor of compensatory roles of the right hemisphere tracts in language functions when the LH networks are disrupted.

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Glass Half Full: Preserved Anatomical Bypasses Predict Variance in Language Functions After Stroke

10.1101/2021.08.31.458462 ◽

2021 ◽

Author(s):

Brian A Erickson ◽

Brian Kim ◽

Benjamin Deck ◽

Dorian Pustina ◽

Andrew Tesla DeMarco ◽

...

Keyword(s):

Right Hemisphere ◽

Shortest Paths ◽

Dorsal Stream ◽

Support Vector ◽

Auditory Comprehension ◽

Language Performance ◽

Language Functions ◽

Stroke Imaging ◽

Shortest Network ◽

The Right

The severity of post-stroke aphasia is related to damage to white matter connections. However, neural signaling can route not only through direct connections, but also along multi-step network paths. When brain networks are damaged by stroke, paths can bypass around the damage to restore communication. The shortest network paths between regions could be the most efficient routes for mediating bypasses. We examined how shortest-path bypasses after left hemisphere strokes were related to language performance. Regions within and outside of the canonical language network could be important in aphasia recovery. Therefore, we innovated methods to measure the influence of bypasses in the whole brain. Distinguishing bypasses from all residual shortest paths is difficult without pre-stroke imaging. We identified bypasses by finding shortest paths in subjects with stroke that were longer than those observed in the average network of the most reliably observed connections in age-matched controls. We tested whether features of those bypasses predicted scores in four orthogonal dimensions of language performance derived from a factor analysis of a battery of language tasks. The features were the length of each bypass in steps, and how many bypasses overlapped on each individual direct connection. We related these bypass features to language factors using grid-search cross-validated Support Vector Regression, a technique that extracts robust relationships in high-dimensional data analysis. We discovered that the length of bypasses reliably predicted variance in lexical production (R2 = .576) and auditory comprehension scores (R2 = .164). Bypass overlaps reliably predicted variance in Lexical Production scores (R2 = .247). The predictive elongation features revealed that bypass efficiency along the dorsal stream and ventral stream were most related to Lexical Production and Auditory Comprehension, respectively. Among the predictive bypass overlaps, increased bypass routing through the right hemisphere putamen was negatively related to lexical production ability.

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Shifting of global aphasia to Wernicke’s aphasia in a patient with intact motor function: a case report

BMC Neurology ◽

10.1186/s12883-021-02131-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Ya-Chi Chuang ◽

Chuan-Ching Liu ◽

I-Ching Yu ◽

Yu-Lin Tsai ◽

Shin-Tsu Chang

Keyword(s):

Computed Tomography ◽

Right Hemisphere ◽

Single Photon ◽

Ct Perfusion ◽

Single Case ◽

Photon Emission ◽

Emission Computed Tomography ◽

Speech Fluency ◽

Language Functions ◽

The Right

Abstract Background Global aphasia without hemiparesis (GAWH) is a rare stroke syndrome characterized by the dissociation of motor and language functions. Here, we present a case of GAWH with the patient later regaining speech fluency. Case presentation A 73-year-old man was admitted to our emergency department immediately after an episode of syncope. On arrival, we noted his global aphasia but without any focal neurologic signs. Computed tomography (CT) perfusion scans showed a large hypodense region over his left perisylvian area. Under the impression of acute ischaemic stroke, he received recombinant tissue plasminogen activator (rtPA) injection and was treated as an inpatient. The patient was later discharged with GAWH status and received regular speech rehabilitation. After 14 months of rehabilitation, the patient gradually recovered his language expression ability. The degree of aphasia was evaluated with the Concise Chinese Aphasia Test (CCAT), and we obtained brain single photon emission computed tomography (SPECT) scans to assess cerebral blood flow. Conclusion A patient with severe impairments of Broca’s and Wernicke’s areas was able to talk fluently despite being unintelligible. SPECT revealed relative high level of radioactivity uptake in the right frontal lobe, suggesting the deficits in speech fluency could have been compensated by the right hemisphere. Although this is a single case demonstration, the results may strengthen the role of the right hemisphere in GAWH patients and suggests additional study that examines the possible benefits of stimulating activity at right homologous regions for recovering language function after global aphasia.

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Are visual working memory and episodic memory distinct processes? Insight from stroke patients by lesion-symptom mapping

Brain Structure and Function ◽

10.1007/s00429-021-02281-0 ◽

2021 ◽

Author(s):

Selma Lugtmeijer ◽

◽

Linda Geerligs ◽

Frank Erik de Leeuw ◽

Edward H. F. de Haan ◽

...

Keyword(s):

Working Memory ◽

Episodic Memory ◽

Visual Working Memory ◽

Visual Memory ◽

Right Hemisphere ◽

Memory Task ◽

Stroke Patients ◽

Lesion Symptom Mapping ◽

Criterion Setting ◽

The Right

AbstractWorking memory and episodic memory are two different processes, although the nature of their interrelationship is debated. As these processes are predominantly studied in isolation, it is unclear whether they crucially rely on different neural substrates. To obtain more insight in this, 81 adults with sub-acute ischemic stroke and 29 elderly controls were assessed on a visual working memory task, followed by a surprise subsequent memory test for the same stimuli. Multivariate, atlas- and track-based lesion-symptom mapping (LSM) analyses were performed to identify anatomical correlates of visual memory. Behavioral results gave moderate evidence for independence between discriminability in working memory and subsequent memory, and strong evidence for a correlation in response bias on the two tasks in stroke patients. LSM analyses suggested there might be independent regions associated with working memory and episodic memory. Lesions in the right arcuate fasciculus were more strongly associated with discriminability in working memory than in subsequent memory, while lesions in the frontal operculum in the right hemisphere were more strongly associated with criterion setting in subsequent memory. These findings support the view that some processes involved in working memory and episodic memory rely on separate mechanisms, while acknowledging that there might also be shared processes.

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Bihemispheric Language: How the Two Hemispheres Collaborate in the Processing of Language

The Speciation of Modern Homo Sapiens ◽

10.5871/bacad/9780197263112.003.0010 ◽

2004 ◽

Author(s):

Norman D. Cook

Keyword(s):

Language Processing ◽

Right Hemisphere ◽

Central Question ◽

Linguistic Processing ◽

Figures Of Speech ◽

Language Functions ◽

Left And Right ◽

Level Of Understanding ◽

The Right

Speech production in most people is strongly lateralized to the left hemisphere (LH), but language understanding is generally a bilateral activity. At every level of linguistic processing that has been investigated experimentally, the right hemisphere (RH) has been found to make characteristic contributions, from the processing of the affective aspects of intonation, through the appreciation of word connotations, the decoding of the meaning of metaphors and figures of speech, to the understanding of the overall coherency of verbal humour, paragraphs and short stories. If both hemispheres are indeed engaged in linguistic decoding and both processes are required to achieve a normal level of understanding, a central question concerns how the separate language functions on the left and right are integrated. This chapter reviews relevant studies on the hemispheric contributions to language processing and the role of interhemispheric communications in cognition.

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

Psychological Medicine ◽

10.1017/s0033291701004706 ◽

2001 ◽

Vol 31 (8) ◽

pp. 1425-1435 ◽

Cited By ~ 122

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.

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Discrepant findings for Wada test and functional magnetic resonance imaging with regard to language function: use of electrocortical stimulation mapping to confirm results

Journal of Neurosurgery ◽

10.3171/jns.2005.102.1.0169 ◽

2005 ◽

Vol 102 (1) ◽

pp. 169-173 ◽

Cited By ~ 25

Author(s):

Kuan H. Kho ◽

Frans S. S. Leijten ◽

Geert-Jan Rutten ◽

Jan Vermeulen ◽

Peter van Rijen ◽

...

Keyword(s):

Magnetic Resonance ◽

Right Hemisphere ◽

Test Results ◽

Functional Magnetic Resonance ◽

Resonance Imaging ◽

Wada Test ◽

Content Type ◽

Language Functions ◽

Imaging Results ◽

The Right

✓ The Wada test is still considered the gold standard for determining the language-dominant hemisphere prior to brain surgery. The authors report on a 34-year-old right-handed woman whose Wada test results indicated that the right hemisphere was dominant for language. In contrast, functional magnetic resonance (fMR) imaging was indicative of bilaterally represented language functions. Activation in the left hemisphere demonstrated on fMR imaging was most pronounced in the Broca area. Importantly, fMR imaging results in this area were confirmed on electrocortical stimulation mapping. These contradictory findings indicated that a right hemispherre dominance for language according to the Wada test should be questioned and verified using electrocortical stimulation. Nonetheless, the question remains whether involvement of these areas in the left frontal hemisphere is critical for language, as these were spared during surgery.

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Motor Extinction in Distinct Reference Frames: A Double Dissociation

Behavioural Neurology ◽

10.1155/2013/181903 ◽

2013 ◽

Vol 26 (1-2) ◽

pp. 111-119 ◽

Cited By ~ 1

Author(s):

Jennifer Heidler-Gary ◽

Mikolaj Pawlak ◽

Edward H. Herskovits ◽

Melissa Newhart ◽

Cameron Davis ◽

...

Keyword(s):

White Matter ◽

Reference Frames ◽

Right Hemisphere ◽

Hand Movements ◽

Lesion Site ◽

Left Hand ◽

Double Dissociation ◽

Ischemic Tissue ◽

The Right ◽

Right Hemisphere Stroke

Objective:Test the hypothesis that right hemisphere stroke can cause extinction of left hand movements or movements of either hand held in left space, when both are used simultaneously, possibly depending on lesion site.Methods:93 non-hemiplegic patients with acute right hemisphere stroke were tested for motor extinction by pressing a counter rapidly for one minute with the right hand, left hand, or both simultaneously with their hands held at their sides, or crossed over midline.Results:We identified two distinct types of motor extinction in separate patients; 20 patients extinguished left hand movements held in left or right space (left canonical body extinction); the most significantly associated voxel cluster of ischemic tissue was in the right temporal white matter. Seven patients extinguished either hand held in left space (left space extinction), and the most significantly associated voxel cluster of ischemic tissue was in right parietal white matter.Conclusions:There was a double dissociation between left canonical body extinction and left space motor extinction. Left canonical body extinction seems to be associated with more dorsal (parietal) ischemia, and left canonical body extinction seems to be associated with more ventral (temporal) ischemia.

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Structural Brain Correlates of Creative Personality

10.1101/2021.01.06.425561 ◽

2021 ◽

Author(s):

Divya Sadana ◽

Rajnish Kumar Gupta ◽

S Senthil Kumaran ◽

Sanjeev Jain ◽

Jamuna Rajeswaran

Keyword(s):

Grey Matter ◽

Inferior Frontal Gyrus ◽

Anterior Cingulate ◽

Grey Matter Volume ◽

Voxel Based Morphometry ◽

Creative Personality ◽

Brain Correlates ◽

The Right ◽

Creative Artists ◽

Age Range

Creative individuals and their enigmatic personalities have always been a subject of fascination. The current study explored the neuroanatomical basis of creative personality using voxel-based morphometry. The sample comprised of two groups - Creative (CR) group (professional creative artists) and matched controls with no demonstrated artistic creativity (NC) with 20 participants in each group, in the age range of 20-40 years, right-handed, and had minimum average intelligence (IQ > 90). Participants in CR were selected using the creativity achievement questionnaire, creativity was assessed using the Wallach & Kogan test of creativity, and personality was administered using NEO-FFI. Results indicated significantly higher openness to new experiences in CR which positively correlates with the right middle frontal gyrus. An increased grey matter volume in the inferior frontal gyrus, anterior cingulate gyrus in CR, pointing towards the integration of cognitive and imaginative processes that might be implicated in creative personality.

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Lateralization of Language

The Oxford Handbook of Neurolinguistics ◽

10.1093/oxfordhb/9780190672027.013.34 ◽

2019 ◽

pp. 876-906

Author(s):

Lise Van der Haegen ◽

Qing Cai

Keyword(s):

Human Brain ◽

Speech Processing ◽

Right Hemisphere ◽

Hemispheric Specialization ◽

Unique Contribution ◽

Language Impaired ◽

Language Functions ◽

Hemisphere Dominance ◽

The Right

It is intriguing that the two brain halves of the human brain look so similar, but are in fact quite different at the anatomical level, and even more so at the functional level. In particular, the highly frequent co-occurrence of right-handedness and left hemisphere dominance of language has led to an abundance of laterality research. This chapter discusses the most important recent finding on laterality (i.e., left or right hemisphere) and degree of hemispheric specialization for speech production, auditory speech processing, and reading. Following a descriptive overview of these three core sub-processes of language, the chapter summarizes possible influences on the lateralization of each, including anatomical, evolutionary, genetic, developmental, and experiential factors, as well as handedness and impairment. It will become clear that language is a heterogeneous cognitive function driven by a variety of underpinning origins. Next, the often-underestimated role of the right hemisphere for language is discussed with respect to prosody and metaphor comprehension, as well as individual differences in the lateralization of healthy and language-impaired brains. Finally, recent insights into the relationship between lateralized language and non-language functions are discussed, highlighting the unique contribution of lateralization research to the growing knowledge of general human brain mechanisms.

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