Phonological and semantic influences on auditory word perception in children with and without reading impairments using magnetoencephalography (MEG) and electroencephalography (EEG)

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2007.Includes bibliographical references (p. 117-135).Children with dyslexia struggle with learning to read despite adequate intelligence, motivation, and schooling. Over the years, there has been a growing consensus about the role of phonological processing in reading disability. Poor readers typically do worse than their normal reading peers on tasks that require phonological processing which has been linked, directly or indirectly, to their speech perception abilities. The work in this thesis combined behavioral, MEG, and EEG methods to examine how normal and reading-impaired children, 7-13 years of age, perceive speech under varying degrees of phonological contrast (1 vs. 3 phonetic features). In a series of auditory word perception experiments, good and poor readers were found to do worse in accuracy and/or reaction times in phonologically similar (i.e., 1-feature contrast) than phonologically dissimilar (i.e., 2 or 3-feature contrast) conditions. Despite the similar behavioral performance and EEG responses for the two groups, a region of interest (ROI) based MEG approach revealed differences in the brain activation of the two groups in superior temporal regions at 140 to 300 ms.(cont.) In the auditory word discrimination task, differences in activation were found in good readers but not poor readers, as a function of the degree of phonological contrast, reflecting poor readers' lack of sensitivity to the phonological characteristics of the word stimuli. In the sentence plausibility judgment task, the impaired phonological processing abilities of the poor readers may have led them to rely more on top-down sentence context to perceptually disambiguate phonologically confusing terminal words, thereby deceiving them into accepting the phonologically similar incongruent sentences as being congruent. This may account for the poor reader group's reduced brain activation in the phonologically demanding condition in the sentence task. The results of the experiments are consistent with a phonological view of reading disability according to which children with reading impairments have poorly defined phonological representations.by Daniel T. Wehner.Ph.D

Neurocognition and behaviour:diagnostic work-up and interventions in Duchenne and Becker muscular dystrophy

Duchenne (DMD) and Becker (BMD) Muscular Dystrophy are hereditary, progressive muscle diseases caused by changes or mutations in the Duchenne Muscular Dystrophy (DMD) gene. This gene is part of the hereditary material, the DNA. These muscle diseases occur almost exclusively in boys. The dystrophin gene is responsible for the production of multiple dystrophin isoforms that occur in different body tissues, namely in the muscles, kidneys, eye and brain. Scientific research in recent years has focused on investigating the link between the disrupted production of dystrophin in the brain and the more frequent occurrence of neurocognitive (i.e. learning and thinking problems) and behavioural problems. The exact role of dystrophin in cognition and behaviour remains unclear. The aim of this thesis was to further describe the relationship between dystrophin in the brain and the common behavioural and neurocognitive problems. In addition, a literature review was used to identify the psychological measurement instruments used in the scientific literature. Finally, little research has been done on treatments to reduce the consequences of behavioural and neurocognitive problems. This dissertation studied two treatments in boys with DMD, namely a psychological intervention (cognitive working memory training) and a medication-based treatment to improve attention (methylphenidate)

The effect of high variability and individual differences on phonetic training of Mandarin tones

High variability phonetic training (HVPT) has been found to be more effective than low variability phonetic training (LVPT) in learning various non-native phonetic contrasts. However, little research has considered whether this applies to the learning of tone contrasts. Two relevant studies suggested that the effect of high variability training depends on the perceptual aptitude of participants (Perrachione, Lee, Ha, & Wong, 2011; Sadakata & McQueen, 2014). It is also unclear how different types of individual difference measures interact with the learning of tonal language. What work there is, suggests that musical ability is related to discriminating tonal information and in general attention and working memory are linked to language learning. The present study extends these findings by examining the interaction between individual aptitude and input variability and between learning outcomes and individual measures using natural, meaningful L2 input (both previous studies used pseudowords). In Study 1, forty English speakers took part in an eight-session phonetic training paradigm. They were assigned to high/low variability training groups. High variability used four speakers during the training sessions while low variability used one. All participants learned real Mandarin tones and words. Individual aptitude was measured using an identification and a categorisation task. Learning was measured using a categorical discrimination task, an identification task and two production tasks. Overall, all groups improved in both production and perception of tones which transferred to novel voices and items, demonstrating the effectiveness of training despite the increased complexity of the training material compared with previous research. Although the low variability group exhibited better learning during training than the high variability group, there was no evidence that the different variability training conditions led to different performances in any of the tests of generalisation. Moreover, although performance on one of the aptitude tasks significantly predicted overall performance in categorical discrimination, identification and training tasks, it did not predict improvement from pre- to post- test. Critically, there was also no interaction between individual aptitude and variability-condition, contradicting with previous findings. One possibility was that the high variability condition was too difficult as speakers were randomly presented during training, resulting in low trial-by-trial consistency. This greater difficulty might block any advantage of variability for generalisation. In order to examine this, Study 2 recruited additional 20 native English speakers and tested them in a further condition, identical to the previous high variability condition except that each speaker was presented in their own block during the training. Although participants performed better in training compared with the high variability group from study 1, there was again no difference in generalisation compared with the previous conditions, and again no interaction between individual aptitude and variability-condition was found. Bayes Factors were also used to assess the null results. There was evidence for the null for the benefits of high variability for generalisation but only ambiguous evidence regarding whether there was interaction between variability and individual aptitude. The HPVT used in Study 1 and Study 2 did not replicate the interaction between variability-condition and aptitude found in previous studies. Moreover, although one of the measures of aptitude did correlate with the baseline measures of performance, there was no evidence that it predicted learning due to training. Additionally, the two individual aptitude measures used in Study 1 and 2 – taken from Perrachione, et al. (2011) and Sadakata and McQueen (2013) – are not comprehensive. They are natural language-related tasks which directly measure tone perception itself, rather than the underlying cognitive factors which could underpin this ability. Another interesting question is whether these different cognitive factors might contribute to learners at different stages differently, particularly since language training studies vary as to whether they use current learners of the language or naïve participants, a factor may contribute towards differing findings in the literature. To explore these issues, Study 3 investigated the relationship between a battery of cognitive individual difference measures and Mandarin tone learning. Sixty native English speakers (forty of whom were currently studying Mandarin at undergraduate level, twenty of whom were naïve learners) took part in a six-session training paradigm. With high-variability training stimuli similar to that used in Study 2 (four speakers blocked), their learning outcomes were assessed by identification, categorical discrimination and production tasks similar to Study 1. Their working memory, attention and musical ability were also measured. Overall, both groups showed improvements during training and in the generalisation tasks. Although Mandarin learner participants performed better than naïve participants overall, the improvements were not generally greater than naïve participants. Each of the individual difference measures was used to predict participant’s performance at pre-test and their improvement due to training. Bayes Factors were used as the key method of inference. For Mandarin learner participants, both performances at pre-test and pre- to- post improvement were strongly predicted by attention measures while for naïve speakers, musical ability was the dominant predictor for pre- to- post improvement. This series of studies demonstrates that Mandarin lexical tones can be trained using natural stimuli embedded in a word learning task and learning generalises to untrained voices and items as well as to production. Although there is no evidence in the current data that the type of training materials affected learning outcomes, tone learning is indeed affected by individual cognitive factors, such as attention and musical ability, with these playing a different role for learners at different stages

The clinical spectrum of sporadic and familial forms of frontotemporal dementia

The term frontotemporal dementia (FTD) describes a clinically, genetically and pathologically diverse group of neurodegenerative disorders. Symptoms of FTD can present in individuals in their twenties through to their nineties, but the mean age at onset is in the sixth decade. The most common presentation is with a change in personality and impaired social conduct (behavioural variant FTD). Less frequently patients present with language problems (primary progressive aphasia). Both of these groups of patients can develop motor features consistent with either motor neuron disease (usually the amyotrophic lateral sclerosis variant) or parkinsonism (most commonly a progressive supranuclear palsy or corticobasal syndrome). In about a third of cases FTD is familial, with mutations in the progranulin, microtubule-associated protein tau and chromosome 9 open reading frame 72 genes being the major causes. Mutations in a number of other genes including TANK-binding kinase 1 are rare causes of familial FTD. This review aims to clarify the often confusing terminology of FTD, and outline the various clinical features and diagnostic criteria of sporadic and familial FTD syndromes. It will also discuss the current major challenges in FTD research and clinical practice, and potential areas for future research. This article is protected by copyright. All rights reserved

Primary progressive aphasia : neuropsychological analysis and evolution

Tese de doutoramento, Ciências Biomédicas (Neurociências), Universidade de Lisboa, Faculdade de Medicina, 2015Frontotemporal lobar degeneration (FTLD) is the second leading cause of early-onset ( 2) revealed some clusters composed mostly by nonfluent or by semantic PPA cases. However, we could not evidence any group chiefly composed of logopenic PPA cases. Hence, findings obtained with the application of unsupervised data mining approaches do not clearly support a logopenic PPA. However further, supervised learning studies may indicate distinct results. Behaviour changes may occur early in PPA but the frequency of these symptoms across the three variants is still controversial. In the third study, 94 consecutive PPA patients (26 nonfluent, 36 semantic, 32 logopenic) underwent language and neuropsychological assessments. The presence of behavioural changes was ascertained by semi-structured informant-based interviews using the Blessed Dementia Rating Scale. Eighty-two percent of the cases endorsed at least one behaviour change. Nonfluent patients presented significantly more behaviour changes and scored more often (46.2%) the item “hobbies relinquished” when compared to logopenic patients. These differences in behaviour symptoms probably reflect distinct underlying neurodegenerative diseases. PPA is a neurodegenerative disorder with no effective pharmacological treatment. Cognition-based interventions are adequate alternatives, but their benefit has not been thoroughly explored. The aim of this last investigation was to study the effect of speech and language therapy (SLT) on naming ability in PPA. An open parallel prospective longitudinal study involving two centers was designed to compare patients with PPA submitted to SLT (1 h/week for 11 months, on average) with patients receiving no therapy. Twenty patients were enrolled and undertook baseline language and neuropsychological assessments; among them, 10 received SLT and 10 constituted an age- and education-matched historical control group. The primary outcome measure was the change in group mean performance on the Snodgrass and Vanderwart Naming Test between baseline and follow-up assessments. Intervention and control groups did not significantly differ on demographic and clinical variables at baseline. A mixed repeated measures ANOVA revealed a significant main effect of therapy (F(1,18) = 10.763; p = 0.005) on the performance on the Snodgrass and Vanderwart Naming Test. Although limited by a non-randomized open study design with a historical control group, the present study suggests that SLT may have a benefit in PPA, and it should prompt a randomized, controlled, rater-blind clinical trial. Conclusion: Despite the recent harmonization efforts, the delineation of certain PPA variants is still controversial. The present results show that neuropsychology is a key instrument not only for the clear definition of PPA subtypes but also for the study of the abnormal mechanisms and features underlying the main forms of PPA. Moreover, a neuropsychological approach to disease management seems to be feasible. Specifically, SLT emerges as an alternative and adequate approach to tackle the increasing language deficits experienced in all PPA phenotypes for some time. The emergence of promising disease-modifying therapies in the context of FTLD, in association with these cognitive-based interventions, will certainly be the future of PPA disease management

Words in Action: retrieval errors in aphasia, a topic for therapy

An aphasia is defined as an acquired impairment of language based on brain damage (Benson & Ardila 1996). All modes of language use may be involved: spontaneous speech, writing and comprehension of written and spoken language. Therefore, aphasia is labelled as a supramodal language disorder. The nature and severity of the disorder in each language mode may vruy between and within individual patients