Time course of evoked-potential changes in different forms of anomia in aphasia

No abstract available

ERP correlates of word production before and after stroke in an aphasic patient

No abstract available

Language specificity of lexical-phonological therapy in bilingual aphasia: A clinical and electrophysiological study

Based on findings for overlapping representations of bilingual people's first (L1) and second (L2) languages, unilingual therapies of bilingual aphasia have been proposed to benefit the untrained language. However, the generalisation patterns of intra- and cross-language and phonological therapy and their neural bases remain unclear. We tested whether the effects of an intensive lexical-phonological training (LPT) in L2 transferred to L1 word production in a Persian-French bilingual stroke patient with Broca's aphasia. Language performance was assessed using the Bilingual Aphasia Test, a 144-item picture naming (PN) task and a word–picture verification (WPV) task. Electroencephalography (EEG) was recorded during PN and WPV in both languages before and after an LPT in French on a wordlist from the PN task. After the therapy, naming improved only for the treated L2 items. The naming performance improved neither in the untrained L2 items nor in the corresponding items in L1. EEG analyses revealed a Language x Session topographic interaction at 540 ms post-stimulus, driven by a modification of the electrophysiological response to the treated L2 but not L1 items. These results indicate that LPT modified the brain networks engaged in the phonological-phonetic processing during naming only in the trained language for the trained items

Die Verarbeitung von Eigennamen im Mandarin-Chinesischen : eine Verhaltens- und Neuroimaging-Studie

Yen H-L. Processing of proper names in Mandarin Chinese : a behavioral and neuroimaging study. Bielefeld (Germany): Bielefeld University; 2006.Proper names have been considered as a universal language class (Bright, 2003; Müller 2004). The distinction between proper names and common nouns has been postulated since several thousand years in ancient Greek and in Chinese philosophy of language (e.g., Kripke, 1972; Wu, 1997). Furthermore, this dissociation has been supported by experimental data (e.g., Müller & Kutas, 1996) and case studies (e.g., Lyons, 2002). This dissertation explores the processing of proper names in Mandarin Chinese in which the morphology of proper names and the tradition of name giving differ greatly from Indo-European languages such as German and English. It aims to figure out whether the theoretically based dissociation has a neurocognitive reality. Besides a behavior study (category decision task), we carried out an auditory and a visual functional magnetic resonance imaging (fMRI) experiment. Forty native speakers of Mandarin Chinese took part in the behavior study whereas twelve different participants participated the fMRI study. For both modalities, forty personal names, forty geographical names and forty common nouns were used as experimental stimuli. Different words were applied in the auditory and the visual experiment. The behavior study tested 20 brand names in addition. In general, Mandarin Chinese speakers of the present study were able to recognize proper names as type (here: personal names and geographical names) significantly faster than common nouns in both auditory and visual modality. In contrast, brand names did not exhibit the faster reaction time than common nouns. The reaction time of brand names was significantly longer than personal names and geographical names. In our fMRI study, processing of proper names and processing of common nouns revealed partially different brain activation patterns. Contrasts between personal names and common nouns as well as contrasts between geographical names and common nouns revealed significant activation. In auditory modality, proper names revealed more activation in bilateral anterior temporal cortices, premotor area and anterior precuneus. In visual modality, proper names evoked significant activation in the frontal lobe including frontal eye fields and premotor area. Despite of modality, common nouns yielded significant activation in the left posterior temporal cortex. Further characteristic of processing of common nouns was activation in occipital area and temporo-parietal junction. Our fMRI findings support the view that processing of proper names and common nouns involve different brain areas. This may due to the difference between general semantic processing and identity-specific semantic processing. Moreover, the corresponding cognitive mechanism of proper name processing may differ from common nouns. The present finding in Mandarin Chinese is also supported by previous research of Indo-European languages. Corresponding to the hypothesis which has been discussed in the philosophy of language over two thousand years, the special status of proper names can be supported by our neurocognitive evidence

Can tDCS enhance treatment of aphasia after stroke?

Background: Recent advances in the application of transcranial direct current stimulation (tDCS) in healthy populations have led to the exploration of the technique as an adjuvant method to traditional speech therapies in patients with post-stroke aphasia. Aims: The purpose of the review is: (i) to review the features of tDCS that make it an attractive tool for research and potential future use in clinical contexts; (ii) to describe recent studies exploring the facilitation of language performance using tDCS in post-stroke aphasia; (iii) to explore methodological considerations of tDCS that may be key to understanding tDCS in treatment of aphasia post stroke; and (iv) to highlight several caveats and outstanding questions that need to be addressed in future work. Main Contribution: This review aims to highlight our current understanding of the methodological and theoretical issues surrounding the use of tDCS as an adjuvant tool in the treatment of language difficulties after stroke. Conclusions: Preliminary evidence shows that tDCS may be a useful tool to complement treatment of aphasia, particularly for speech production in chronic stroke patients. To build on this exciting work, further systematic research is needed to understand the mechanisms of tDCS-induced effects, its application to current models of aphasia recovery, and the complex interactions between different stimulation parameters and language rehabilitation techniques. The potential of tDCS is to optimise language rehabilitation techniques and promote long-term recovery of language. A stimulating future for aphasia rehabilitation