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16 result(s) for "Ekert, Justyna O."
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Discriminators of pseudoprogression and true progression in high-grade gliomas: A systematic review and meta-analysis
High-grade gliomas remain the most common primary brain tumour with limited treatments options and early recurrence rates following adjuvant treatments. However, differentiating true tumour progression (TTP) from treatment-related effects or pseudoprogression (PsP), may critically influence subsequent management options. Structural MRI is routinely employed to evaluate treatment responses, but misdiagnosis of TTP or PsP may lead to continuation of ineffective or premature cessation of effective treatments, respectively. A systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses method. Embase, MEDLINE, Web of Science and Google Scholar were searched for methods applied to differentiate PsP and TTP, and studies were selected using pre-specified eligibility criteria. The sensitivity and specificity of included studies were summarised. Three of the identified methods were compared in a separate subgroup meta-analysis. Thirty studies assessing seven distinct neuroimaging methods in 1372 patients were included in the systematic review. The highest performing methods in the subgroup analysis were DWI (AUC = 0.93 [0.91–0.95]) and DSC-MRI (AUC = 0.93 [0.90–0.95]), compared to DCE-MRI (AUC = 0.90 [0.87–0.93]). 18F-fluoroethyltyrosine PET (18F-FET PET) and amide proton transfer-weighted MRI (APTw-MRI) also showed high diagnostic accuracy, but results were based on few low-powered studies. Both DWI and DSC-MRI performed with high sensitivity and specificity for differentiating PsP from TTP. Considering the technical parameters and feasibility of each identified method, the authors suggested that, at present, DSC-MRI technique holds the most clinical potential.
A functional dissociation of the left frontal regions that contribute to single word production tasks
Controversy surrounds the interpretation of higher activation for pseudoword compared to word reading in the left precentral gyrus and pars opercularis. Specifically, does activation in these regions reflect: (1) the demands on sublexical assembly of articulatory codes, or (2) retrieval effort because the combinations of articulatory codes are unfamiliar? Using fMRI, in 84 neurologically intact participants, we addressed this issue by comparing reading and repetition of words (W) and pseudowords (P) to naming objects (O) from pictures or sounds. As objects do not provide sublexical articulatory cues, we hypothesis that retrieval effort will be greater for object naming than word repetition/reading (which benefits from both lexical and sublexical cues); while the demands on sublexical assembly will be higher for pseudoword production than object naming. We found that activation was: (i) highest for pseudoword reading [P>O&W in the visual modality] in the anterior part of the ventral precentral gyrus bordering the precentral sulcus (vPCg/vPCs), consistent with the sublexical assembly of articulatory codes; but (ii) as high for object naming as pseudoword production [P&O>W] in dorsal precentral gyrus (dPCg) and the left inferior frontal junction (IFJ), consistent with retrieval demands and cognitive control. In addition, we dissociate the response properties of vPCg/vPCs, dPCg and IFJ from other left frontal lobe regions that are activated during single word speech production. Specifically, in both auditory and visual modalities: a central part of vPCg (head and face area) was more activated for verbal than nonverbal stimuli [P&W>O]; and the pars orbitalis and inferior frontal sulcus were most activated during object naming [O>W&P]. Our findings help to resolve a previous discrepancy in the literature, dissociate three functionally distinct parts of the precentral gyrus, and refine our knowledge of the functional anatomy of speech production in the left frontal lobe.
Dissociating the functions of three left posterior superior temporal regions that contribute to speech perception and production
Prior studies have shown that the left posterior superior temporal sulcus (pSTS) and left temporo-parietal junction (TPJ) both contribute to phonological short-term memory, speech perception and speech production. Here, by conducting a within-subjects multi-factorial fMRI study, we dissociate the response profiles of these regions and a third region – the anterior ascending terminal branch of the left superior temporal sulcus (atSTS), which lies dorsal to pSTS and ventral to TPJ. First, we show that each region was more activated by (i) 1-back matching on visually presented verbal stimuli (words or pseudowords) compared to 1-back matching on visually presented non-verbal stimuli (pictures of objects or non-objects), and (ii) overt speech production than 1-back matching, across 8 types of stimuli (visually presented words, pseudowords, objects and non-objects and aurally presented words, pseudowords, object sounds and meaningless hums). The response properties of the three regions dissociated within the auditory modality. In left TPJ, activation was higher for auditory stimuli that were non-verbal (sounds of objects or meaningless hums) compared to verbal (words and pseudowords), irrespective of task (speech production or 1-back matching). In left pSTS, activation was higher for non-semantic stimuli (pseudowords and hums) than semantic stimuli (words and object sounds) on the dorsal pSTS surface (dpSTS), irrespective of task. In left atSTS, activation was not sensitive to either semantic or verbal content. The contrasting response properties of left TPJ, dpSTS and atSTS was cross-validated in an independent sample of 59 participants, using region-by-condition interactions. We also show that each region participates in non-overlapping networks of frontal, parietal and cerebellar regions. Our results challenge previous claims about functional specialisation in the left posterior superior temporal lobe and motivate future studies to determine the timing and directionality of information flow in the brain networks involved in speech perception and production.
A systematic review of cognitive interventions for adult patients with brain tumours
Background Neurocognitive impairments are common in patients with current or previously treated brain tumours, and such impairments can negatively affect patient outcomes including quality of life and survival. This systematic review aimed to identify and describe interventions used to ameliorate (improve) or prevent cognitive impairments in adults with brain tumours. Methods We performed a literature search of the Ovid MEDLINE, PsychINFO and PsycTESTS databases from commencement until September 2021. Results In total, 9998 articles were identified by the search strategy; an additional 14 articles were identified through other sources. Of these, 35 randomised and nonrandomised studies were deemed to meet the inclusion/exclusion criteria of our review and were subsequently included for evaluation. A range of interventions were associated with positive effects on cognition, including pharmacological agents such as memantine, donepezil, methylphenidate, modafinil, ginkgo biloba and shenqi fuzheng, and nonpharmacological interventions such as general and cognitive rehabilitation, working memory training, Goal Management Training, aerobic exercise, virtual reality training combined with computer‐assisted cognitive rehabilitation, hyperbaric oxygen therapy and semantic strategy training. However, most identified studies had a number of methodological limitations and were judged to be at moderate‐to‐high risk of bias. In addition, it remains unclear whether and to what extent the identified interventions lead to durable cognitive benefits after cessation of the intervention. Conclusion The 35 studies identified in this systematic review have indicated potential cognitive benefits for a number of pharmacological and nonpharmacological interventions in patients with brain tumours. Study limitations were identified and further studies should focus on improved study reporting, methods to reduce bias and minimise participant drop‐out and withdrawal where possible, and consider standardisation of methods and interventions across studies. Greater collaboration between centres could result in larger studies with standardised methods and outcome measures, and should be a focus of future research in the field. This systematic review provides a comprehensive overview of 35 studies of interventions for cognition in adult patients with brain tumours, identifying potential cognitive benefits for a number of pharmacological or nonpharmacological interventions. There were limitations in the identified studies, and further studies should focus on improved study reporting and methods (including blinding of outcome assessors) to reduce bias, methods to minimise participant drop‐out and withdrawal where possible, and consider standardisation of methods and interventions across studies.
The Effect of Right Temporal Lobe Gliomas on Left and Right Hemisphere Neural Processing During Speech Perception and Production Tasks
Using fMRI, we investigated how right temporal lobe gliomas affecting the posterior superior temporal sulcus alter neural processing observed during speech perception and production tasks. Behavioural language testing showed that three pre-operative neurosurgical patients with grade 2, grade 3 or grade 4 tumours had the same pattern of mild language impairment in the domains of object naming and written word comprehension. When matching heard words for semantic relatedness (a speech perception task), these patients showed under-activation in the tumour infiltrated right superior temporal lobe compared to 61 neurotypical participants and 16 patients with tumours that preserved the right postero-superior temporal lobe, with enhanced activation within the (tumour-free) contralateral left superior temporal lobe. In contrast, when correctly naming objects (a speech production task), the patients with right postero-superior temporal lobe tumours showed higher activation than both control groups in the same right postero-superior temporal lobe region that was under-activated during auditory semantic matching. The task dependent pattern of under-activation during the auditory speech task and over-activation during object naming was also observed in eight stroke patients with right hemisphere infarcts that affected the right postero-superior temporal lobe compared to eight stroke patients with right hemisphere infarcts that spared it. These task-specific and site-specific cross-pathology effects highlight the importance of the right temporal lobe for language processing and motivate further study of how right temporal lobe tumours affect language performance and neural reorganisation. These findings may have important implications for surgical management of these patients, as knowledge of the regions showing functional reorganisation may help to avoid their inadvertent damage during neurosurgery.
A Data-Based Approach for Selecting Pre- and Intra-Operative Language Mapping Tasks
Background: Pre- and intra-operative language mapping in neurosurgery patients frequently involves an object naming task. The choice of the optimal object naming paradigm remains challenging due to lack of normative data and standardization in mapping practices. The aim of this study was to identify object naming paradigms that robustly and consistently activate classical language regions and could therefore be used to improve the sensitivity of language mapping in brain tumor and epilepsy patients. Methods: Functional magnetic resonance imaging (fMRI) data from two independent groups of healthy controls (total = 79) were used to generate threshold-weighted voxel-based consistency maps. This novel approach allowed us to compare inter-subject consistency of activation for naming single objects in the visual and auditory modality and naming two objects in a phrase or a sentence. Results: We found that the consistency of activation in language regions was greater for naming two objects per picture than one object per picture, even when controlling for the number of names produced in 5 s. Conclusion: More consistent activation in language areas for naming two objects compared to one object suggests that two-object naming tasks may be more suitable for delimiting language eloquent regions with pre- and intra-operative language testing. More broadly, we propose that the functional specificity of brain mapping paradigms for a whole range of different linguistic and non-linguistic functions could be enhanced by referring to databased models of inter-subject consistency and variability in typical and atypical brain responses.
Neuromodulatory Control and Language Recovery in Bilingual Aphasia: An Active Inference Approach
Understanding the aetiology of the diverse recovery patterns in bilingual aphasia is a theoretical challenge with implications for treatment. Loss of control over intact language networks provides a parsimonious starting point that can be tested using in-silico lesions. We simulated a complex recovery pattern (alternate antagonism and paradoxical translation) to test the hypothesis—from an established hierarchical control model—that loss of control was mediated by constraints on neuromodulatory resources. We used active (Bayesian) inference to simulate a selective loss of sensory precision; i.e., confidence in the causes of sensations. This in-silico lesion altered the precision of beliefs about task relevant states, including appropriate actions, and reproduced exactly the recovery pattern of interest. As sensory precision has been linked to acetylcholine release, these simulations endorse the conjecture that loss of neuromodulatory control can explain this atypical recovery pattern. We discuss the relevance of this finding for other recovery patterns.
Degeneracy in the neurological model of auditory speech repetition
Both classic and contemporary models of auditory word repetition involve at least four left hemisphere regions: primary auditory cortex for processing sounds; pSTS (within Wernicke’s area) for processing auditory images of speech; pOp (within Broca’s area) for processing motor images of speech; and primary motor cortex for overt speech articulation. Previous functional-MRI (fMRI) studies confirm that auditory repetition activates these regions, in addition to many others. Crucially, however, contemporary models do not specify how regions interact and drive each other during auditory repetition. Here, we used dynamic causal modelling, to test the functional interplay among the four core brain regions during single auditory word and pseudoword repetition. Our analysis is grounded in the principle of degeneracy—i.e., many-to-one structure-function relationships—where multiple neural pathways can execute the same function. Contrary to expectation, we found that, for both word and pseudoword repetition, (i) the effective connectivity between pSTS and pOp was predominantly bidirectional and inhibitory; (ii) activity in the motor cortex could be driven by either pSTS or pOp; and (iii) the latter varied both within and between individuals. These results suggest that different neural pathways can support auditory speech repetition. This degeneracy may explain resilience to functional loss after brain damage. A fMRI analysis of human participants performing speech repetition tasks provides evidence for the existence of multiple, degenerate neural pathways capable of facilitating auditory repetition.
Reforming support systems of newly diagnosed brain cancer patients: a systematic review
Purpose Despite the increasing incidence of currently incurable brain cancer, limited resources are placed in patients’ support systems, with reactive utilisation late in the disease course, when physical and psychological symptoms have peaked. Based on patient-derived data and emphasis on service improvement, this review investigated the structure and efficacy of the support methods of newly diagnosed brain cancer patients in healthcare systems. Methods This systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols. Articles from PubMed, Embase, and CENTRAL databases were screened with six pre-established eligibility criteria, including assessment within 6 months from diagnosis of a primary malignant brain tumour. Risk of bias was evaluated using the Newcastle–Ottawa Scale and Critical Appraisal Skills Program (CASP) Qualitative Studies Checklist. Results Of 5057 original articles, 14 were eligible for qualitative synthesis. Four studies were cross-sectional and ten were descriptive. Information given to patients was evaluated in seven studies, communication with patients in nine, and patient participation in treatment decisions in eight. Risk of bias was low in ten studies, moderate in two, and high in two. Conclusions Techniques promoting individualised care increased perceived support, despite poor patient-physician communication and complexity of the healthcare system. Extracted data across 14 included studies informed a set of guidelines and a four-step framework. These can help evaluate and reform healthcare services to better accommodate the supportive needs of this patient group.
Mapping and anatomo-surgical techniques for SMA-cingulum-corpus callosum gliomas; how I do it
BackgroundAwake brain mapping paradigms are variable, particularly in SMA, and not personalised to each patient. In addition, subpial resections do not offer full protection to vascular injury, as the pia can be easily violated.MethodsMapping paradigms developed by a multidisciplinary brain mapping team. During resection, a combined subpial/interhemispheric approach allowed early identification and arterial skeletonization. Precise anatomo-surgical dissection of the affected cingulum and corpus callosum was achieved.ConclusionsIn SMA-cingulum-CC tumours, a combined subpial/interhemispheric approach reduces risk of vascular injury allowing precise anatomo-surgical dissections. Knowledge of cognitive functions of affected parcels is likely to offer best outcomes.