Left Hemisphere Lesions Research Articles

Iowa Brain-Behavior Modeling Toolkit: An Open-Source MATLAB Tool for Inferential and Predictive Modeling of Imaging-Behavior and Lesion-Deficit Relationships.

The traditional analytical framework taken by neuroimaging studies in general, and lesion-behavior studies in particular, has been inferential in nature and has focused on identifying and interpreting statistically significant effects within the sample under study. While this framework is well-suited for hypothesis testing approaches, achieving the modern goal of precision medicine requires a different framework that is predictive in nature and that focuses on maximizing the predictive power of models and evaluating their ability to generalize beyond the data that were used to train them. However, few tools exist to support the development and evaluation of predictive models in the context of neuroimaging or lesion-behavior research, creating an obstacle to the widespread adoption of predictive modeling approaches in the field. Further, existing tools for lesion-behavior analysis are often unable to accommodate categorical outcome variables and often impose restrictions on the predictor data. Researchers therefore often must use different software packages and analytical approaches depending on whether they are addressing a classification vs. regression problem and on whether their predictor data correspond to binary lesion images, continuous lesion-network images, connectivity matrices, or other data modalities. To address these limitations, we have developed a MATLAB software toolkit that supports both inferential and predictive modeling frameworks, accommodates both classification and regression problems, and does not impose restrictions on the modality of the predictor data. The toolkit features both a graphical user interface and scripting interface, includes implementations of multiple mass-univariate, multivariate, and machine learning models, features built-in and customizable routines for hyper-parameter optimization, cross-validation, model stacking, and significance testing, and automatically generates text-based descriptions of key methodological details and modeling results to improve reproducibility and minimize errors in the reporting of methods and results. Here, we provide an overview and discussion of the toolkit features and demonstrate its functionality by applying it to the question of how expressive and receptive language impairments relate to lesion location, structural disconnection, and functional network disruption in a large sample of patients with left hemispheric brain lesions. We find that impairments in expressive vs. receptive language are most strongly associated with left lateral prefrontal and left posterior temporal/parietal damage, respectively. We also find that impairments in expressive vs. receptive language are associated with partially overlapping patterns of fronto-temporal structural disconnection, and that the associated functional networks are also similar. Importantly, we find that lesion location and lesion-derived network measures are highly predictive of both types of impairment, with predictions from models trained on these measures explaining ~30-40% of the variance on average when applied to data from patients not used to train the models. We have made the toolkit publicly available, and we have included a comprehensive set of tutorial notebooks to support new users in applying the toolkit in their studies.

Bihemispheric IDH-Wildtype Glioblastoma with Unilateral FGFR3-TACC3 Fusion in Patient with Breast Cancer History: A Case Report and Literature Review

Abstract Introduction/Objective Adult IDH-wild type glioblastomas comprise a heterogeneous spectrum of neoplasms, characterized by poor prognosis and resistance to the chemoradiotherapy. For WHO integrated diagnosis classification and to establish treatment options, molecular analysis is necessary. Herein, we present a case of a glioblastoma, IDH-wildtype with involvement of both cerebral hemispheres and an uncharacteristic in-frame fusion limited to one hemisphere. Methods/Case Report The patient is a 52-year-old woman with past medical history of metastatic breast cancer who presented with headache and worsening facial pain. Brain magnetic resonance imaging brain demonstrated a right frontal lobe lesion with vasogenic edema. The patient was treated with Gamma Knife radiosurgery. Scans revealed enlargement and a new left frontal lobe lesion. Bihemispheric tumor resection and GammaTile placement was undertaken. Results (if a Case Study enter NA) Histologically, the tumor was composed of hypercellular astrocytes, microvascular proliferation, and necrosis with no evidence of metastatic disease. Immunohistochemistically, neoplastic cells showed glial fibrillary acidic protein expression and elevated Ki-67 proliferation index. Molecular examination revealed in the right hemisphere lesion post-radiation (1) FGFR3::TACC3 (exon 17::exon 11) fusion and (2) TERT promoter, while the left hemisphere lesion which did not receive radiation showed clinically relevant variants in (1) TERT promoter, (2) TP53, (3) NF1, and (3) PIK3CA without identification of a fusion. An integrated diagnosis of glioblastoma, IDH- wildtype, CNS WHO grade 4 was established bilaterally. Conclusion The fibroblast growth factor receptor 3 (FGFR3)-transforming acidic coiled-coil 3 (TACC3) fusion is identified as a rare molecular feature in glioblastomas with an estimated prevalence of 4%. Clinical trials suggest that F3T3-positive tumors have a better prognosis than those without the translocation. The identification of the oncogenic FGFR3-TACC3 fusion highlights the possibility of identifying patients potentially responsive to targeted therapy with FGFR kinase inhibitors. The significance of the molecular differences in the right and left hemisphere lesions is uncertain; glioblastomas are heterogeneous tumors with intra-and intertumoral heterogeneity but it may suggest independent origins.

The Impact of Stimulation Parameters on Cardiovascular Outcomes in Chronic Stroke Patients Following Transcranial Direct Current Stimulation-A Pilot Controlled, Randomized, Double-Blind Crossover Trial.

Stroke survivors often experience autonomic nervous system (ANS) dysfunction. While Transcranial Direct Current Stimulation (tDCS) has been shown to modulate the ANS when applied to the left hemisphere, its effects on the right hemisphere remain unexplored. We aimed to compare the effects of tDCS applied to both the injured and the contralateral hemispheres on heart rate variability (HRV) and functional capacity in individuals post-stroke. Twenty individuals with cerebral hemisphere lesions (ten with right-hemisphere lesions and ten with left-hemisphere lesions) were randomized into four groups: anodal and sham tDCS on the left temporal cortex (T3) and anodal and sham tDCS on the right temporal cortex (T4). HRV was assessed before the intervention, after the six-minute walk test (6MWT), and following tDCS. HRV data were categorized into frequency ranges: low frequency (LF), high frequency (HF), and sympathovagal balance. The 6MWT (meters) was conducted both pre- and post-tDCS. In individuals with right-hemisphere lesions, a higher global LF value was observed (right side: 71.4 ± 16.8 nu vs. left side: 65.7 ± 17.3 nu; p = 0.008), as well as lower values of the HF component (right side: 29.5 ± 18.9 nu vs. left side: 34.0 ± 17.4 nu; p = 0.047), consequently exhibiting higher global values of the low/high-frequency ratio (right side: 3.9 ± 2.8 vs. left side: 2.9 ± 2.4). Regarding the stimulation site, tDCS over T3 led to a lower overall value of the low/high-frequency ratio (left hemisphere: 3.0 ± 2.2 vs. right hemisphere: 3.7 ± 2.9; p = 0.040) regardless of the lesion location. A significant increase in the distance covered in the 6MWT was observed for individuals with lesions in both hemispheres after tDCS at T3. Participants with right-hemisphere lesions exhibited superior global sympathetic autonomic nervous system activity. When the tDCS was applied on the left hemisphere, it maintained lower sympathovagal balance values and improved functional capacity regardless of the hemisphere affected by the stroke.

Recovery of Visuospatial Neglect With Standard Treatment: A Systematic Review and Meta-Analysis.

Visuospatial neglect is a common consequence of stroke and is characterized by impaired attention to contralesional space. Currently, the extent and time course of recovery from neglect are not clearly established. This systematic review and meta-analysis aimed to determine the recovery trajectory of poststroke neglect with standard treatment. PsycInfo, Embase, and MEDLINE were searched for articles reporting recovery rates of neglect after stroke. Time since stroke was categorized into early (0-3 months), mid (3-6 months), and late (>6 months) recovery phases. Random-effects models for pooled prevalence were generated for each phase, and potential sources of heterogeneity were explored with metaregressions. Methodological quality of each study was assessed using the Joanna Briggs Institute checklist, with low-quality studies excluded in sensitivity analyses. The search captured 4130 articles including duplicates, and 111 full-text reviews were undertaken. A total of 27 studies reporting data from 839 stroke survivors with neglect were included for review. Meta-analyses indicated a recovery rate of 42% in the early phase, which increased to 53% in the mid-recovery phase. Additional recovery in the late phase was minimal, with an estimated 56% recovery rate. Heterogeneity of studies was high (I2>75%) in all 3 phases of recovery. Estimates were robust to sensitivity analyses. Metaregressions showed significantly greater recovery in studies that included patients with left-hemisphere lesions (β=0.275, P<0.05, I2=84%). Most recovery from neglect occurs in the first 3 months, although additional gains can be expected up to 6 months poststroke. While a large proportion of patients recover from neglect, over 40% show persistent symptoms. Further research is needed on effective rehabilitation interventions, particularly focusing on patients most at risk of chronic visuospatial neglect. URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42023388763.

Comparative Analysis of Brain Coping Mechanisms in Small Left-Hemisphere Lesions: Incidental vs. Symptomatic Gliomas.

Incidentally discovered low-grade gliomas (iLGGs) are very rare and little is still known about their associated functional imaging activation patterns, white-matter status, and plasticity potential. Recent studies shed light on several clinical factors responsible for the good clinical status observed in these patients versus those with their symptomatic counterpart (sLGGs), including small volume. Comparisons were typically carried out by comparing iLGGs with the wider and more heterogeneous sLGG group. In this study, we investigated whether iLGGs affect the brain differently from comparably small sLGGs. Starting from a sample of 13 patients with iLGG, in the current comparative cross-sectional study, we identified a group of patients with sLGGs, primarily matched by lesion volume. We looked for potential differences between the two groups in language-related functional and structural parameters (the fMRI network associated with naming and white-matter fascicles). The t-test did not show significant differences in the fMRI network, but these emerged when performing masking. No significant differences were observed at the white-matter level. Given that small volumes characterized both groups and that demographic variables were comparable, too, we hypothesized that differences between the two groups could be attributed to alternative lesion-related parameters. We discussed these findings from clinical and neurosurgical perspectives.

Can Lesions in the Right Basal Ganglia Cause Aphasia? Crossed Aphasia in a Right-Handed Patient.

Aphasia is a common neurocognitive disorder caused by impaired speech and language, with stroke being the most frequent cause. The neuroanatomical mechanism underlying this condition is not yet fully understood. This case describes a 74-year-old Caucasian woman admitted with a clinical picture of right total anterior circulation infarct (TACI) and aphasia, scoring 17 on the National Institutes of Health Stroke Scale. Neuroimaging showed a large cortico-subcortical frontotemporoparietal and insular infarct involving the basal ganglia of the right hemisphere and bilateral focal atherosclerotic stenosis on the M1 segment of the middle cerebral artery. There was no left hemispheric lesion or abnormal electric activity on the electroencephalogram. A formal evaluation was compatible with transcortical motor aphasia. The aetiological study revealed atrial fibrillation, and the case was admitted as an ischaemic stroke of undetermined aetiology with two possible causes - intracranial atherosclerotic stenosis or atrial fibrillation. Our patient fulfilled all the formal criteria for crossed aphasia in dextral (CAD): aphasia, a lesion in the right hemisphere coupled with the structural integrity of the left hemisphere, an established preference for right-hand use without a familial history of left-handedness individuals, and an absence of brain damage in childhood. Our patient's case adds to the evidence that deep structures - alone or in combination with cortical structures - are primarily affected in CAD. The diagnostic criteria for crossed aphasia in dextral (CAD) are derived from clinical case studies and include aphasia, a lesion in the right hemisphere, a strong preference for using the right hand, the structural integrity of the left hemisphere and no history of brain damage during childhood.The right lentiform nucleus was found to be the most frequent anatomical substrate involved in CAD patients, consistent with our case description.Our patient experienced transcortical motor aphasia due to a stroke in the right hemisphere, adding to the evidence that in CAD patients, deep structures are primarily affected. In contrast, in left hemispheric lesions, cortical structures seem to be the main culprits.

The effect of hemispheric lesion location on trunk control.

Trunk control is the basic component of postural control, and achieving trunk control is a complex process that can be achieved by dynamically building and maintaining neuromuscular function. Lateropulsion, which is also defined as the body falling to one side, is considered an important condition that is frequently encountered after stroke and affects trunk control. It is known that there are differences in the regulation of postural control and trunk control according to hemispheric localization. We had a very specific group of patients and tried to find out the outcomes prospectively in this study. The patients were divided into 2 groups those with right hemisphere lesions (Group 1) and those with left hemisphere lesions (Group 2). Comorbidity and cognitive function were evaluated using the Charlson Comorbidity Index (CMI) and Standardized Mini-Mental State Test (SMMSE). Activities of daily living were evaluated using the Turkish version of the Modified Barthel Index (MBI). The Stroke Rehabilitation Assessment of Movement Instrument (STREAM) test was used to assess trunk control and the Brunnstrom (BS) test was used to assess motor functions. There was a significant difference between Groups 1 and 2 in terms of STREAM in lower extremity scores were higher in Group 2 (P < .05). The number of patients in BS lower extremity Stages IV-VI was higher in Group 1 and Group 2 (P < .05). It was determined that upper extremity, lower extremity and Total STREAM scores and BS Hand stage in Group 2 were significantly higher than Group 1 in patients with total middle cerebral artery (MCA) affected(P < .05). It was determined that trunk control was more affected in patients with right hemispheric lesions. Additionally, trunk control is significantly affected in patients with total MCA lesions.

Application of virtual reality technologies in the rehabilitation of patients with left and right hemisphere lesions in the acute period of ischemic stroke

BACKGROUND: Currently, neurocognitive rehabilitation with the integration of innovative virtual reality (VR) technologies is the standard component of early rehabilitation treatment programs for patients with acute focal brain damage. AIM: Based on the statistical methodology, this study aimed to evaluate the efficiency of neurocognitive rehabilitation with the application VR technologies in patients with left and right hemisphere lesions in the acute period of ischemic stroke. MATERIALS AND METHODS: The study examined 160 patients diagnosed with ischemic stroke exhibiting cognitive impairments. Patients were divided into two groups based on stroke localization: group 1 (n=80) had left hemisphere lesions, whereas group 2 (n=80) had left hemisphere lesions. Since day 5 of hospitalization, in addition to basic therapy, rehabilitation was performed using a hardware–software multimedia complex based on VR for remote-controlled rehabilitation «Devirta-Delphi». Rehabilitation efficiency (RE) was assessed by testing objectively quantitative measures of accuracy and coordination of movement performance before and after treatment using a Kinect Delphi system. Cognitive and psychoemotional measures were assessed by neuropsychological tests on days 2–4 of hospitalization and at the end of the VR therapy. Mathematical statistics were calculated using Python programming language and its libraries Pandas and SciPy. RESULTS: Higher RE values were obtained in patients with right-sided stroke. Irrespective of lesion lateralization, significant improvement was noted with respect to mnestic, executive function, and ideomotor praxis, regression of anxiety, depression, and general aggression. Group 1 also showed an improvement in speech function and a decrease in general asthenia, whereas group 2 showed an increase in attention and emotion recognition ability. Factors that negatively affected RE were identified, namely, apathy, anxiety, prestroke cognitive decline, semantic aphasia, and decreased attention in group 1 and semantic and visual–spatial impairments, prestroke decline, and recurrent stroke in group 2. CONCLUSION: The application of an immersive environment in the early rehabilitation of patients with cognitive impairment improves the performance of verbal and visual tests reflecting mnestic, regulatory, and neurodynamic executive functions in lesions with different lateralization.

Pars Opercularis Underlies Efferent Predictions and Successful Auditory Feedback Processing in Speech: Evidence From Left-Hemisphere Stroke.

Hearing one's own speech allows for acoustic self-monitoring in real time. Left-hemisphere motor planning regions are thought to give rise to efferent predictions that can be compared to true feedback in sensory cortices, resulting in neural suppression commensurate with the degree of overlap between predicted and actual sensations. Sensory prediction errors thus serve as a possible mechanism of detection of deviant speech sounds, which can then feed back into corrective action, allowing for online control of speech acoustics. The goal of this study was to assess the integrity of this detection-correction circuit in persons with aphasia (PWA) whose left-hemisphere lesions may limit their ability to control variability in speech output. We recorded magnetoencephalography (MEG) while 15 PWA and age-matched controls spoke monosyllabic words and listened to playback of their utterances. From this, we measured speaking-induced suppression of the M100 neural response and related it to lesion profiles and speech behavior. Both speaking-induced suppression and cortical sensitivity to deviance were preserved at the group level in PWA. PWA with more spared tissue in pars opercularis had greater left-hemisphere neural suppression and greater behavioral correction of acoustically deviant pronunciations, whereas sparing of superior temporal gyrus was not related to neural suppression or acoustic behavior. In turn, PWA who made greater corrections had fewer overt speech errors in the MEG task. Thus, the motor planning regions that generate the efferent prediction are integral to performing corrections when that prediction is violated.

Accelerated decline in motor suppression in patients with cerebrovascular disorders: A kinetic analysis using the square-tracing task.

Patients with cerebrovascular disorders (CVDs) tend to exhibit impulsive behaviour without controlling their movements, leading to difficulty in performing activities of daily living and an increased risk of accidents. This hastiness, termed 'pacing impairment', has been studied but is not fully understood. To experimentally examine the kinetic features of pacing impairment by focusing on changes in speed and investigating neuropsychological substrates. We instructed 53 inpatients with CVDs, 20 orthopaedic inpatients, and 20 healthy participants to trace a 200 mm-sided square as slowly as possible for 120 seconds. We measured the tracing length and mean acceleration and examined the relationship between these measurements, neuropsychological symptoms, and lesion sites. Gradual acceleration in drawing, i.e., decline in motor suppression, was observed more frequently in the CVD group than in the control groups. Excessive acceleration was associated with unilateral spatial neglect, frontal lobe signs, and attention disorders but not with motor impersistence. Additionally, the incidence of excessive acceleration did not differ between left and right hemisphere lesion subgroups and was not associated with any specific lesion site. Pacing impairment can manifest as general or holistic deficits in attentional function widely distributed throughout the cerebral hemispheres.

Bayesian modelling disentangles language versus executive control disruption in stroke.

Stroke is the leading cause of long-term disability worldwide. Incurred brain damage can disrupt cognition, often with persisting deficits in language and executive capacities. Yet, despite their clinical relevance, the commonalities and differences between language versus executive control impairments remain under-specified. To fill this gap, we tailored a Bayesian hierarchical modelling solution in a largest-of-its-kind cohort (1080 patients with stroke) to deconvolve language and executive control with respect to the stroke topology. Cognitive function was assessed with a rich neuropsychological test battery including global cognitive function (tested with the Mini-Mental State Exam), language (assessed with a picture naming task), executive speech function (tested with verbal fluency tasks), executive control functions (Trail Making Test and Digit Symbol Coding Task), visuospatial functioning (Rey Complex Figure), as well as verbal learning and memory function (Soul Verbal Learning). Bayesian modelling predicted interindividual differences in eight cognitive outcome scores three months after stroke based on specific tissue lesion topologies. A multivariate factor analysis extracted four distinct cognitive factors that distinguish left- and right-hemispheric contributions to ischaemic tissue lesions. These factors were labelled according to the neuropsychological tests that had the strongest factor loadings: One factor delineated language and general cognitive performance and was mainly associated with damage to left-hemispheric brain regions in the frontal and temporal cortex. A factor for executive control summarized mental flexibility, task switching and visual-constructional abilities. This factor was strongly related to right-hemispheric brain damage of posterior regions in the occipital cortex. The interplay of language and executive control was reflected in two distinct factors that were labelled as executive speech functions and verbal memory. Impairments on both factors were mainly linked to left-hemispheric lesions. These findings shed light onto the causal implications of hemispheric specialization for cognition; and make steps towards subgroup-specific treatment protocols after stroke.

Reading and Writing Impairment in Persons with Crossed Aphasia: A Comparative Study

Abstract Background Persons with aphasia (PWAs) manifest multifaceted deficits like auditory comprehension, spoken language, reading, and writing to varying degrees. Of these, the most debilitating signs are reading and writing impairment. Of late, PWAs express greater interest to improve their reading and writing skills. The deficits in these skills along with deficits in spoken language limit their participation in the community. Reading and writing may be altered contrarily in various stroke conditions across the left and right hemisphere lesions, just like how linguistic impairments are mutually exclusive. Thus, it must be rational to reconcile the possible role of the right hemisphere to process reading and writing inversely alike spoken abilities. Additionally, investigations on reading and writing deficits in left cerebrovascular atrophy (CVA) aphasics and right CVA aphasics (crossed aphasia) are seldom reported in the literature with relevance to Indian population focusing Indian languages. The study aims to compare reading and writing abilities across PWAs with left CVA and right CVA (crossed aphasia). Methodology The study recruited four native Kannada speaking PWAs (6 months poststroke) aged between 40 and 70 years with impaired linguistic abilities secondary to stroke through convenient sampling. Western Aphasia Battery-Kannada was administered to identify aphasic component, specifically to evaluate the language, reading, and writing aspects in detail and the scores were analyzed based on the scoring. Results Descriptive statistics revealed both left and crossed PWAs performed equipotent on linguistics tasks. However, reading abilities were better in left CVA individuals and writing was better in crossed PWAs on comparing the mean scores. Correlation analysis revealed positive correlation between language and reading-writing abilities of left CVA PWAs. Negative correlation was evinced in crossed PWAs. Hence, reading and writing difficulties in crossed aphasia can be mostly ascribed to impairment in peripheral mechanisms involved in visual and/or kinesthetic information processing as the right hemisphere is most viable to these processes. Conclusion The study highlights the unique pattern of reading and writing abilities in crossed aphasia condition. However, careful examination of dissociations in acquired spoken language and written language abilities across differential neuronal networks through larger samples in the future research is warranted.

Correlation between lesion location and dysphagia characteristics in post-stroke patients

ObjectiveTo assess the correlation between lesion location and swallowing function characteristics in post-stroke dysphagia (PSD) patients. Materials and methodsWe enrolled 133 PSD. The patients were divided into supratentorial and infratentorial stroke groups. We compared the measurements in the videofluoroscopic swallowing study (VFSS) with 3ml and 5 ml of diluted and thickened barium liquid data between supratentorial and brainstem stroke groups. We further compared the difference of VFSS measurements between patients with left hemispheric or right hemispheric lesions (further divided into unilateral hemispheric cortical and subcortical subgroups) and brianstem leison stroke group.To explore the lesion location's effect on different bolus volume, the VFSS measurements of 3ml and 5ml in each subgroups were compared respectively. The measurements of VFSS included the oral transit time, soft palate elevation duration, hyoid bone movement duration (HMD), UES opening duration, pharyngeal transit duration (PTD), stage of ansition duration, and laryngeal closure duration (LCD), the upper esophageal sphincter opening (UESO), hyoid bone superior horizontal displacement, and hyoid bone anterior horizontal displacement. General swallowing function was assessed using the Penetration Aspiration Scale (PAS) and Functional Oral Intake Scale (FOIS). We performed the paired t-test, Spearman's correlation, and Kruskal–Wallis test analysis to characterize the parameters among the groups. ResultsFifty-eight patients were assessed in the final analysis. The HMD (p = 0.019), PTD (p = 0.048) and LCD (p = 0.013) were significantly different between the supratentorial and brainstem lesion groups in 5ml volume. The HMD was significantly different (p = 0.045) between the left cortical and brainstem lesion groups. Significant differences in the HMD (p = 0.037) and LCD (p = 0.032) between the left subcortical and brainstem lesion groups were found in 5ml volume bolus. There was no group different when taking the 3ml volume bolus. Regarding the relationship between food bolus volume and swallowing functions, only the UESO demonstrated a significant difference in the subcortical lesion of the right hemisphere (p = 0.0032) compared the 3 ml and 5 ml volume bolus. The PTD demonstrated a moderate correlation with the PAS scores (r = 0.38, p = 0.0044). The HMD (r = 0.32, p = 0.018) and LCD (r = 0.29, p = 0.039) demonstrated weak correlations with the PAS scores. We did not identify any correlation between the VFSS parameters and FOIS scores in each subgroup level. ConclusionThe PSD with brainstem lesion shows more sever dysfunction in the pharyngeal phases. The left hemisphere was engaged in both the oral and pharyngeal phases. Lesions in the bilateral cortical, subcortical, and brainstem regions may impair sensory input.

Abstract TMP34: Lower Limb Motor Performance is Proportional to Corticospinal Tract Integrity in Chronic Stroke

Introduction: Gait is a complex behavior characterized by an array of measures, each contributing to our understanding of gait performance. To improve gait recovery after stroke, we need to connect complex clinical function and brain structure. Here, our purpose is to evaluate the relationship between lower limb performance and structural integrity of corticospinal tract (CST) in ambulatory chronic stroke survivors. Methods: Diffusion weighted images (DWIs) and lower limb performance measures were acquired from 36 chronic (&gt;6 months) stroke survivors with lower limb deficits. Clinical measures included Fugl-Meyer(FM), Gait Assessment and Intervention Tool (GAIT), timed-up-and-go (TUG) and fastest gait speed (GS). Lesions were manually outlined on the MRIs, and left hemisphere lesions were flipped. DWIs were preprocessed using standard denoising techniques before calculating fractional anisotropy (FA), mean diffusivity (MD) and radial diffusivity (RD). Tract-based spatial statistics (TBSS) was used to normalize all data to MNI space and project it onto a skeleton of white matter tracts. CSTs were isolated. Voxel-wise analysis was performed with permutation testing (5000 permutations). A regression model was created for each clinical variable using lesion masks as a regressor. Results: Participants were 64±8.9 y/o, 83% male and 53% left hemisphere lesion. FM was 24.1±4.1. Mild correlations were present for FM with GAIT (Pearson, r = -0.33, p = 0.045) and GS (r = 0.34, p = 0.038), and GS with GAIT (r = -0.35, p = 0.036). TUG was highly correlated with GS (r = -0.93, p = 0.000). In exploratory analysis, findings for ipsilesional CST were as follows: 1) better FM was associated with higher FA, MD and RD, p = 0.001, 0.002 and 0.006 respectively; 2) better GS with higher FA, p = 0.034,3) better TUG scores with lower RD, p = 0.041 and 4) a trend of GAIT with RD, p=0.054. Location of statistically significant voxels varied for different clinical measures. No associations were found for contralesional CST. Conclusion: Structural correlates of lower limb performance can be detected using diffusion weighted tractography. FM, an impairment measure of paretic limb, has a stronger association with CST integrity than the measures of global gait function (TUG and GS).

"Non-Eloquent" brain regions predict neuropsychological outcome in tumor patients undergoing awake craniotomy.

Supratotal resection of primary brain tumors is being advocated especially when involving "non-eloquent" tissue. However, there is extensive neuropsychological data implicating functions critical to higher cognition in areas considered "non-eloquent" by most surgeons. The goal of the study was to determine pre-surgical brain regions that would be predictive of cognitive outcome at 4-6 months post-surgery. Cortical reconstruction and volumetric segmentation were performed with the FreeSurfer-v6.0 image analysis suite. Linear regression models were used to regress cortical volumes from both hemispheres, against the total cognitive z-score to determine the relationship between brain structure and broad cognitive functioning while controlling for age, sex, and total segmented brain volume. We identified 62 consecutive patients who underwent planned awake resections of primary (n = 55, 88%) and metastatic at the University of New Mexico Hospital between 2015 and 2019. Of those, 42 (23 males, 25 left hemispheric lesions) had complete pre and post-op neuropsychological data available and were included in this study. Overall, total neuropsychological functioning was somewhat worse (p = 0.09) at post-operative neuropsychological outcome (Mean = -.20) than at baseline (Mean = .00). Patients with radiation following resection (n = 32) performed marginally worse (p = .036). We found that several discrete brain volumes obtained pre-surgery predicted neuropsychological outcome post-resection. For the total sample, these volumes included: left fusiform, right lateral orbital frontal, right post central, and right paracentral regions. Regardless of lesion lateralization, volumes within the right frontal lobe, and specifically right orbitofrontal cortex, predicted neuropsychological difference scores. The current study highlights the gaps in our current understanding of brain eloquence. We hypothesize that the volume of tissue within the right lateral orbital frontal lobe represents important cognitive reserve capacity in patients undergoing tumor surgery. Our data also cautions the neurosurgeon when considering supratotal resections of tumors that do not extend into areas considered "non-eloquent" by current standards.

The key role of the right posterior fusiform gyrus in music reading: an electrical neuroimaging study on 90 readers

IntroductionIn this study, we employed a combined electromagnetic recording technique, i.e., electroencephalogram (EEG)/event-related potentials (ERPs) plus standardized weighted low-resolution electromagnetic tomography (swLORETA), to investigate the neural mechanism subserving the orthographic processing of symbols in language and music. While much is known about word processing, the current literature remains inconclusive regarding music reading, as its mechanisms appear to be left lateralized in some cases (as suggested by music-alexia clinical case reports) and either right-sided or bilateral in others, depending on the study and the methodology used.MethodsIn this study, 90 right-handed participants with varying musical abilities and sexes performed an attentional selection task that involved the recognition of target letters and musical notes, while their EEG signals were recorded from 128 sites.ResultsThe occipito/temporal N170 component of ERPs (170–210 ms) was found strictly left-sided during letter selection and bilateral (with a right-hemispheric tendency) during note selection. Source reconstruction data indicated the preponderant engagement of the right posterior fusiform gyrus (BA19) for processing musical notes. Also involved were other brain regions belonging to the word reading circuit, including the left-sided visual word form area (VWFA) and frontal eye-fields (FEFs).DiscussionThis finding provides an explanation for the infrequent appearance of musical alexia cases (previously observed only in patients with left hemispheric lesions). It also suggests how musical literacy could be a rehabilitative and preventive factor for dyslexia, by promoting neuroplasticity and bilaterality in the reading areas.

An immersive virtual reality tool for assessing left and right unilateral spatial neglect.

The reported rate of the occurrence of unilateral spatial neglect (USN) is highly variable likely due to the lack of validity and low sensitivity of classical tools used to assess it. Virtual reality (VR) assessments try to overcome these limitations by proposing immersive and complex environments. Nevertheless, existing VR-based tasks are mostly focused only on near space and lack analysis of psychometric properties and/or clinical validation. The present study evaluates the clinical validity and sensitivity of a new immersive VR-based task to assess USN in the extra-personal space and examines the neuronal correlates of deficits of far space exploration. The task was administrated to two groups of patients with right (N = 28) or left (N = 11) hemispheric brain lesions, also undergoing classical paper-and-pencil assessment, as well as a group of healthy participants. Our VR-based task detected 44% of neglect cases compared to 31% by paper-and-pencil tests in the total sample. Importantly, 30% of the patients (with right or left brain lesions) with no clear sign of USN on the paper-and-pencil tests performed outside the normal range in the VR-based task. Voxel lesion-symptom mapping revealed that deficits detected in VR were associated with lesions in insular and temporal cortex, part of the neural network involved in spatial processing. These results show that our immersive VR-based task is efficient and sensitive in detecting mild to strong manifestations of USN affecting the extra-personal space, which may be undetected using standard tools.

Connected Language Performance in Neurotypical and Persons with Aphasia: Use of the Brazilian-Portuguese Story Retell Procedure

Introduction: It is important to analyze the micro- and macrostructure of connected language production across languages in neurotypical and impaired speakers such as people with aphasia (PWA). However, the validity, reliability, sensitivity, or specificity of the available Brazilian-Portuguese connected language production batteries remains untested. Objective: The purpose of this study was to provide a preliminary assessment of the translated Brazilian-Portuguese Story Retell Procedure (SRP-BP) in PWA and neurotypical control participants (NCPs) and investigate whether the SRP can serve as a measure of overall communication impairment in PWA. Methods: This cross-sectional study was developed at the Federal University of São Paulo. Seven right-handed PWA and 14 NCPs were recruited. PWA had a single left-hemisphere post-stroke lesion and were without severe aphasia or non-fluent aphasia that might interfere with performing the SRP. The connected language measures calculated from the SRP-BP were the numbers of words, information units, and propositions produced. The data were analyzed with the non-parametric Mann-Whitney test. Results: The NCPs produced significantly more information units and propositions in each of the 12 SRP-BP stories than the PWA group. The same group results were found for the number of words for 11 of the 12 stories, with no statistically significant difference between groups for the Água (Water) story. Conclusion: The SRP-BP distinguished the connected language production of PWA from that of NCPs. These results motivate additional psychometric assessment and test development of the SRP-BP in neurotypical, PWA, and other language and cognitively impaired populations.

Characterization and individual-level prediction of cognitive state in the first year after 'mild' stroke.

Mild stroke affects more than half the stroke population, yet there is limited evidence characterizing cognition over time in this population, especially with predictive approaches applicable at the individual-level. We aimed to identify patterns of recovery and the best combination of demographic, clinical, and lifestyle factors predicting individual-level cognitive state at 3- and 12-months after mild stroke. In this prospective cohort study, the Montreal Cognitive Assessment (MoCA) was administered at 3-7 days, 3- and 12-months post-stroke. Raw changes in MoCA and impairment rates (defined as MoCA<24 points) were compared between assessment time-points. Trajectory clusters were identified using variations of ≥1 point in MoCA scores. To further compare clusters, additional assessments administered at 3- and 12-months were included. Gamma and Quantile mixed-effects regression were used to predict individual MoCA scores over time, using baseline clinical and demographic variables. Model predictions were fitted for each stroke survivor and evaluated using model cross-validation to identify the overall best predictors of cognitive recovery. Participants' (n = 119) MoCA scores improved from baseline to 3-months (p<0.001); and decreased from 3- to 12-months post-stroke (p = 0.010). Cognitive impairment rates decreased significantly from baseline to 3-months (p<0.001), but not between 3- and 12-months (p = 0.168). Nine distinct trajectory clusters were identified. Clinical characteristics between clusters at each time-point varied in cognitive outcomes but not in clinical and/or activity participation outcomes. Cognitive performance at 3- and 12-months was best predicted by younger age, higher physical activity levels, and left-hemisphere lesion side. More than half of mild-stroke survivors are at risk of cognitive decline one year after stroke, even when preceded by a significantly improving pattern in the first 3-months of recovery. Physical activity was the only modifiable factor independently associated with cognitive recovery. Individual-level prediction methods may inform the timing and personalized application of future interventions to maximize cognitive recovery post-stroke.

Affective Prosody and Its Impact on the Neurology of Language, Depression, Memory and Emotions.

Based on the seminal publications of Paul Broca and Carl Wernicke who established that aphasic syndromes (disorders of the verbal-linguistic aspects of communication) were predominantly the result of focal left-hemisphere lesions, "language" is traditionally viewed as a lateralized function of the left hemisphere. This, in turn, has diminished and delayed the acceptance that the right hemisphere also has a vital role in language, specifically in modulating affective prosody, which is essential for communication competency and psychosocial well-being. Focal lesions of the right hemisphere may result in disorders of affective prosody (aprosodic syndromes) that are functionally and anatomically analogous to the aphasic syndromes that occur following focal left-hemisphere lesions. This paper will review the deductive research published over the last four decades that has elucidated the neurology of affective prosody which, in turn, has led to a more complete and nuanced understanding of the neurology of language, depression, emotions and memory. In addition, the paper will also present the serendipitous clinical observations (inductive research) and fortuitous inter-disciplinary collaborations that were crucial in guiding and developing the deductive research processes that culminated in the concept that primary emotions and related display behaviors are a lateralized function of the right hemisphere and social emotions, and related display behaviors are a lateralized function of the left hemisphere.