Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz?
نویسندگان
چکیده
Two groups of male university students who had been diagnosed as dyslexic when younger, and two groups of control subjects of similar age and IQ to the dyslexics, were scanned whilst reading aloud and during a task where reading was implicit. The dyslexics performed less well than their peers on a range of literacy tasks and were strikingly impaired on phonological tasks. In the reading aloud experiment, simple words and pseudowords were presented at a slow pace so that reading accuracy was equal for dyslexics and controls. Relative to rest, both normal and dyslexic groups activated the same peri- and extra-sylvian regions of the left hemisphere that are known to be involved in reading. However, the dyslexic readers showed less activation than controls in the left posterior inferior temporal cortex [Brodmann area (BA) 37, or Wernicke's Wortschatz], left cerebellum, left thalamus and medial extrastriate cortex. In the implicit reading experiment, word and pseudoword processing was contrasted to visually matched false fonts while subjects performed a feature detection paradigm. The dyslexic readers showed reduced activation in BA 37 relative to normals suggesting that this group difference, seen in both experiments, resides in highly automated aspects of the reading process. Since BA 37 has been implicated previously in modality-independent naming, the reduced activation may indicate a specific impairment in lexical retrieval. Interestingly, during the reading aloud experiment only, there was increased activation for the dyslexics relative to the controls in a pre-motor region of Broca's area (BA 6/44). We attribute this result to the enforced use of an effortful compensatory strategy involving sublexical assembly of articulatory routines. The results confirm previous findings that dyslexic readers process written stimuli atypically, based on abnormal functioning of the left hemisphere reading system. More specifically, we localize this deficit to the neural system underlying lexical retrieval.
منابع مشابه
سوگیری حافظه ناآشکار و آشکار در افراد افسرده بر اساس پردازش انتقال مناسب
The aim of the present research was to examine implicit and explicit memory bias in depressed individuals based on the Transfer Appropriate Processing (TAP) framework. For this purpose, 60 participants (30 outpatient depressed participants for the experimental group and 30 non-depressed participants for the control group) were selected as research sample based on psychiatric interviews of DSM-I...
متن کاملNumber-word reading as challenging task in dyslexia? An ERP study.
The aim of the present study was to evaluate processes of lexical access, selection and early semantic access in young native Hungarian students as well as in dyslexics compensating successfully for their reading problems of developmental origin. The present study made use of the well-known lexical decision paradigm in which event-related potentials (ERPs) elicited by words, number-words and ps...
متن کاملElectrophysiological correlates of impaired reading in dyslexic pre-adolescent children.
In this study, event related potentials (ERPs) were used to investigate the extent to which dyslexics (aged 9-13 years) differ from normally reading controls in early ERPs, which reflect prelexical orthographic processing, and in late ERPs, which reflect implicit phonological processing. The participants performed an implicit reading task, which was manipulated in terms of letter-specific proce...
متن کاملLexical and sublexical orthographic processing: an ERP study with skilled and dyslexic adult readers.
This ERP study investigated the cognitive nature of the P1-N1 components during orthographic processing. We used an implicit reading task with various types of stimuli involving different amounts of sublexical or lexical orthographic processing (words, pseudohomophones, pseudowords, nonwords, and symbols), and tested average and dyslexic readers. An orthographic regularity effect (pseudowords-n...
متن کاملDyslexics are impaired on implicit higher-order sequence learning, but not on implicit spatial context learning.
Developmental dyslexia is characterized by poor reading ability and impairments on a range of tasks including phonological processing and processing of sensory information. Some recent studies have found deficits in implicit sequence learning using the serial reaction time task, but others have not. Other skills, such as global visuo-spatial processing may even be enhanced in dyslexics, althoug...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Brain : a journal of neurology
دوره 122 ( Pt 10) شماره
صفحات -
تاریخ انتشار 1999