Reliability of single-subject neural activation patterns in speech production tasks

Traditional group fMRI (functional magnetic resonance imaging) analyses are not designed to detect individual differences that may be crucial to better understanding speech disorders. Single-subject research could therefore provide a richer characterization of the neural substrates of speech production in development and disease. Before this line of research can be tackled, however, it is necessary to evaluate whether healthy individuals exhibit reproducible brain activation across multiple sessions during speech production tasks. In the present study, we evaluated the reliability and discriminability of cortical functional magnetic resonance imaging data from twenty neurotypical subjects who participated in two experiments involving reading aloud mono- or bisyllabic speech stimuli. Using traditional methods like the Dice and intraclass correlation coefficients, we found that most individuals displayed moderate to high reliability, with exceptions likely due to increased head motion in the scanner. Further, this level of reliability for speech production was not directly correlated with reliable patterns in the underlying average blood oxygenation level dependent signal across the brain. Finally, we found that a novel machine-learning subject classifier could identify these individuals by their speech activation patterns with 97% accuracy from among a dataset of seventy-five subjects. These results suggest that single-subject speech research would yield valid results and that investigations into the reliability of speech activation in people with speech disorders are warranted.Accepted manuscrip

Convergent and divergent fMRI responses in children and adults to increasing language production demands

In adults, patterns of neural activation associated with perhaps the most basic language skill—overt object naming—are extensively modulated by the psycholinguistic and visual complexity of the stimuli. Do children's brains react similarly when confronted with increasing processing demands, or they solve this problem in a different way? Here we scanned 37 children aged 7–13 and 19 young adults who performed a well-normed picture-naming task with 3 levels of difficulty. While neural organization for naming was largely similar in childhood and adulthood, adults had greater activation in all naming conditions over inferior temporal gyri and superior temporal gyri/supramarginal gyri. Manipulating naming complexity affected adults and children quite differently: neural activation, especially over the dorsolateral prefrontal cortex, showed complexity-dependent increases in adults, but complexity-dependent decreases in children. These represent fundamentally different responses to the linguistic and conceptual challenges of a simple naming task that makes no demands on literacy or metalinguistics. We discuss how these neural differences might result from different cognitive strategies used by adults and children during lexical retrieval/production as well as developmental changes in brain structure and functional connectivity

MRI neuroimaging: language recovery in adult aphasia due to stroke

Thesis (Ph.D.)--Boston UniversityThis research focuses on the contribution of magnetic resonance imaging (MRI) to understanding recovery and treatment of aphasia in adults who have suffered a stroke. There are three parts. Part 1 presents the feasibility of the application of an overt, picture-naming, functional MRI (fMRI) paradigm to examine neural activity in chronic, nonfluent aphasia (four mild-moderate and one severe nonfluent/global patient). The advantages and disadvantages of an overt, object picture-naming, fMRI block-design paradigm are discussed. An overt naming fMRI design has potential as a method to provide insight into recovery from adult aphasia including plasticity of the brain after left hemisphere stroke and response to treatment. Part 2 uses the overt naming fMRI paradigm to examine changes in neural activity (neural plasticity) after a two-week series of repetitive transcranial magnetic stimulation (rTMS) treatments to improve picture naming in chronic nonfluent aphasia. An overview of rTMS and rationale for use of rTMS as a clinical treatment for aphasia is provided. Patterns of fMRI activation are examined in two patients with chronic nonfluent aphasia following a two-week series of 1 Hz rTMS treatments to suppress the right pars triangularis portion of the right hemisphere, Broca's homologue. One patient responded well, and the other did not. Differences in fMRI activation in response to the rTMS treatment for the two patients may be due to differences in the patients' lesion sites and extent of damage within each lesion site. Part 3 examines the area of the corpus callosum (CC) in 21 chronic nonfluent aphasia patients and 13 ageequivalent controls using structural MRI. Understanding brain morphology and potential atrophy of the CC in chronic stroke patients may shed light on alterations in the interhemispheric dynamics after stroke, especially patterns of brain reorganization during post-stroke language recovery. A decrease in interhemispheric connections has implications for mechanisms of language recovery and potential success with specific treatment methods. Future directions of both structural and functional neuroimaging to study language recovery in adult aphasia are discussed

Fluency and Speech Rate in Children with Localization-Related Epilepsy: Correlations with fMRI Profiles

Fluency and speech rate were examined in children with epilepsy, a group known to demonstrate depressed language skills. We also sought possible functional markers of increased disfluency during speech production tasks regardless of group. Children with epilepsy had significantly more disfluencies in their narratives than their typically-developing peers, while speech rate did not differ between groups. fMRI activation in working memory regions during a covert language processing task was significantly correlated with increased disfluency in another task involving narrative speech production. Additionally, there was a significant positive correlation between disfluency frequency and laterality of activation in the cerebellum. These results support the hypothesis that children with weaker language skills demonstrate increased levels of disfluencies in their narrative speech. Findings also suggest that children with higher rates of conversational speech disfluency may activate additional language and working memory regions when processing language, possibly reflecting the need for more mid-utterance incremental processing

What Can Glioma Patients Teach Us about Language (Re)Organization in the Bilingual Brain: Evidence from fMRI and MEG

Published: 25 May 2021Recent evidence suggests that the presence of brain tumors (e.g., low-grade gliomas) triggers language reorganization. Neuroplasticity mechanisms called into play can transfer linguistic functions from damaged to healthy areas unaffected by the tumor. This phenomenon has been reported in monolingual patients, but much less is known about the neuroplasticity of language in the bilingual brain. A central question is whether processing a first or second language involves the same or different cortical territories and whether damage results in diverse recovery patterns depending on the language involved. This question becomes critical for preserving language areas in bilingual brain-tumor patients to prevent involuntary pathological symptoms following resection. While most studies have focused on intraoperative mapping, here, we go further, reporting clinical cases for five bilingual patients tested before and after tumor resection, using a novel multimethod approach merging neuroimaging information from fMRI and MEG to map the longitudinal reshaping of the language system. Here, we present four main findings. First, all patients preserved linguistic function in both languages after surgery, suggesting that the surgical intervention with intraoperative language mapping was successful in preserving cortical and subcortical structures necessary for brain plasticity at the functional level. Second, we found reorganization of the language network after tumor resection in both languages, mainly reflected by a shift of activity to right hemisphere nodes and the recruitment of ipsilesional left nodes. Third, we found that this reorganization varied according to the language involved, indicating that L1 and L2 follow different reshaping patterns after surgery. Fourth, oscillatory longitudinal effects were correlated with BOLD laterality changes in superior parietal and middle frontal areas. These findings may reflect that neuroplasticity impacts on the compensatory involvement of executive control regions, supporting the allocation of cognitive resources as a consequence of increased attentional demands. Furthermore, these results hint at the complementary role of this neuroimaging approach in language mapping, with fMRI offering excellent spatial localization and MEG providing optimal spectrotemporal resolutionThis research was supported by the Ikerbasque Foundation; by the Basque Government through the BERC 2018 2021 program; by the Spanish State Research Agency through BCBL Severo Ochoa excellence accreditation SEV 2015 0490; by the Fundación Científica AECC (FCAECC) through the project PROYE20005CARR; by a Juan de la Cierva Fellowship to LA (IJCI 2017 31373); and by the Spanish Ministry of Economy and Competitiveness through the Plan Nacional RTI2018 096216 A I00 (MEGLIOMA) to LA and RTI2018 093547 B I00 (LANGCONN) to MC and IQ

Eficácia de uma abordagem integrada de intervenção neurolinguística na afasia progressiva primária

In the past few years, primary progressive aphasia has been acknowledged as an emerging field of practice. Considered a neurodegenerative-based syndrome, primary progressive aphasia requires a singular pathway that addresses the associated characteristics of the syndrome. Among the several treatment approaches that have been investigated, behavioural interventions seem to offer some promise. Despite evidence suggests that intervention should capitalize on spared language abilities and improve communication performance to increase functioning levels, a large number of interventions has focused on remediating impaired skills. Accordingly, the present work aimed to design, implement and evaluate the effects of an intervention that targets the maintenance of a core vocabulary and the training of communication strategies along with the use of augmentative and alternative communication devices. Particularly, this case report aimed to analyse the effect of a neurolinguistic intervention on naming performance for trained and untrained words, and quality of life. Two patients diagnosed with primary progressive aphasia participated in this study that took place over the period of five months. Data collection occurred before intervention, during intervention every two-week interval, immediately after the intervention and one month after treatment was complete. Outcome measures consisted of formal and standardized instruments, adapted and validated to Portuguese population. The intervention approach used in this study produced a limited but promising impact on participants. One participant improved naming accuracy and both participants retained therapy gains. Several methodological aspects limited the outcomes representativeness and generalization of conclusions to clinical practice, namely the reduced number of participants, the presence of different diagnosis and the design. This study provides preliminary data on the effects of combined intervention approaches and their impact on patients’ quality of life. The involvement of close family members on therapy sessions is highlighted as beneficial.A afasia progressiva primária tem sido reconhecida como uma área de intervenção emergente nos últimos anos. Considerando-se uma síndrome de origem neurodegenerativa, a afasia progressiva primária requer uma resposta diferenciada que vá ao encontro das características inerentes a esta condição. Várias abordagens de intervenção têm sido exploradas, de entre as quais se destacam as intervenções comportamentais, pelos resultados promissores que têm oferecido. Embora se defenda cada vez mais que a intervenção se deva focar na manutenção de competências linguísticas residuais e na maximização das competências comunicativas, no sentido de aumentar os níveis de funcionalidade da pessoa, grande parte das intervenções têm valorizado a reaprendizagem de competências perdidas. Neste sentido, o presente trabalho teve como principal objetivo desenhar, implementar e avaliar os efeitos de uma intervenção que promove a manutenção de um vocabulário funcional e o treino de estratégias comunicativas a par da utilização de meios de comunicação aumentativa e alternativa. Especificamente, este estudo de caso visou analisar o efeito de uma intervenção neurolinguística na capacidade de nomeação de palavras treinadas e não treinadas, e qualidade de vida. Dois pacientes diagnosticados com afasia progressiva primária participaram no estudo que teve uma duração total de cinco meses. Foram recolhidos dados antes da intervenção, durante a intervenção a cada duas semanas, imediatamente após a intervenção e um mês após o fim do tratamento. Para tal foram utilizados instrumentos de medida formais e estandardizados, adaptados e aferidos à população portuguesa. A abordagem de intervenção implementada teve um impacto limitado, mas promissor, nos participantes. Registou-se uma melhoria das competências de nomeação num dos casos, e manutenção de competências adquiridas em ambos os casos. Vários fatores metodológicos limitaram a representatividade dos resultados obtidos e aplicabilidade das conclusões à prática clínica, nomeadamente o reduzido número de participantes, a heterogeneidade no diagnóstico e o desenho do estudo. Os resultados deste estudo providenciam dados preliminares acerca do efeito de abordagens integradas de intervenção e impacto na qualidade de vida das pessoas com afasia progressiva primária. Destaca-se a importância do envolvimento de familiares diretos nas sessões terapêuticas, como fator facilitador.Programa Doutoral em Psicologi

An examination of the language construct in NIMH's research domain criteria:Time for reconceptualization!

The National Institute of Mental Health’s Research Domain Criteria (RDoC) Initiative “calls for the development of new ways of classifying psychopathology based on dimensions of observable behavior.” As aresult of this ambitious initiative, language has been identifi d as an independent construct in the RDoC matrix. In this article, we frame language within an evolutionary and neuro- psychological context and discuss some of the limitations to the current measurements of language. Findings from genomics and the neuroimaging of performance during language tasks are dis- cussed in relation to serious mental illness and within the context of caveats regarding measuring language. Indeed, the data collec- tion and analysis methods employed to assay language have been both aided and constrained by the available technologies, methodologies, and conceptual defi Consequently, differ- ent fields of language research show inconsistent defi s of language that have become increasingly broad over time. Individ- ually, they have also shown significant improvements in conceptual resolution, aswell as inexperimental and analytic techniques. More recently, language research has embraced collaborations across disciplines, notably neuroscience, cognitive science, and computa- tional linguistics and has ultimately re-defi classical ideas of language. As we move forward, the new models of language with their remarkably multifaceted constructs force a re-examination of the NIMH RDoC conceptualization of language and thus the neuroscience and genetics underlying this concept

Imaging short- and long-term training success in chronic aphasia

<p>Abstract</p> <p>Background</p> <p>To date, functional imaging studies of treatment-induced recovery from chronic aphasia only assessed short-term treatment effects after intensive language training. In the present study, we show with functional magnetic resonance imaging (fMRI), that different brain regions may be involved in immediate versus long-term success of intensive language training in chronic post-stroke aphasia patients.</p> <p>Results</p> <p>Eight patients were trained daily for three hours over a period of two weeks in naming of concrete objects. Prior to, immediately after, and eight months after training, patients overtly named trained and untrained objects during event-related fMRI. On average the patients improved from zero (at baseline) to 64.4% correct naming responses immediately after training, and treatment success remained highly stable at follow-up. Regression analyses showed that the degree of short-term treatment success was predicted by increased activity (compared to the pretraining scan) bilaterally in the hippocampal formation, the right precuneus and cingulate gyrus, and bilaterally in the fusiform gyri. A different picture emerged for long-term training success, which was best predicted by activity increases in the right-sided Wernicke's homologue and to a lesser degree in perilesional temporal areas.</p> <p>Conclusion</p> <p>The results show for the first time that treatment-induced language recovery in the chronic stage after stroke is a dynamic process. Initially, brain regions involved in memory encoding, attention, and multimodal integration mediated treatment success. In contrast, long-term treatment success was predicted mainly by activity increases in the so-called 'classical' language regions. The results suggest that besides perilesional and homologue language-associated regions, functional integrity of domain-unspecific memory structures may be a prerequisite for successful (intensive) language interventions.</p