The cerebellum and English grammatical morphology: evidence from production, comprehension, and grammaticality judgments.
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Three neuropsychological experiments on a group of 16 cerebellar patients and 16 age- and education-matched controls investigated the effects of damage to the cerebellum on English grammatical morphology across production, comprehension, and grammaticality judgment tasks. In Experiment 1, participants described a series of pictures previously used in studies of cortical aphasic patients. The cerebellar patients did not differ significantly from the controls in the total number of words produced or in the proportion of closed-class words. They did differ to a marginally significant extent in the production of required articles. In Experiment 2, participants identified the agent in a series of aurally presented sentences in which three agency cues (subject-verb agreement, word order, and noun animacy) were manipulated. The cerebellar patients were less affected than the controls were by the manipulation of subject-verb agreement to a marginally significant extent. In Experiment 3, participants performed a grammaticality judgment task on a series of aurally presented sentences. The cerebellar patients were significantly less able to discriminate grammatical and ungrammatical sentences than the controls were, particularly when the error was of subject-verb agreement as opposed to word order. The results suggest that damage to the cerebellum can result in subtle impairments in the use of grammatical morphology, and are discussed in light of hypothesized roles for the cerebellum in language. (+info)
Neural changes following remediation in adult developmental dyslexia.
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Brain imaging studies have explored the neural mechanisms of recovery in adults following acquired disorders and, more recently, childhood developmental disorders. However, the neural systems underlying adult rehabilitation of neurobiologically based learning disabilities remain unexplored, despite their high incidence. Here we characterize the differences in brain activity during a phonological manipulation task before and after a behavioral intervention in adults with developmental dyslexia. Phonologically targeted training resulted in performance improvements in tutored compared to nontutored dyslexics, and these gains were associated with signal increases in bilateral parietal and right perisylvian cortices. Our findings demonstrate that behavioral changes in tutored dyslexic adults are associated with (1) increased activity in those left-hemisphere regions engaged by normal readers and (2) compensatory activity in the right perisylvian cortex. Hence, behavioral plasticity in adult developmental dyslexia involves two distinct neural mechanisms, each of which has previously been observed either for remediation of developmental or acquired reading disorders. (+info)
The time and space of lexicality: a neuromagnetic view.
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Illuminating the neural mechanisms subserving lexico-semantic processing is requisite to further understanding the neurophysiological basis of the dyslexias. Yet, despite numerous functional neuroimaging experiments, the location and temporal behavior of brain regions mediating word-level language processing remain an area of debate. Such investigations typically utilize the word/pseudoword contrast within hemodynamic measurements, and report several left hemisphere regions that respond more strongly to pseudowords but fail to replicate neural areas unique to real word processing. The present experiment addressed this problem from a different perspective. Mainly, we hypothesized that the time course, but not the neuroanatomy, would show within-subject across-condition disparities. For that purpose, we applied dipole-modeling techniques to high-density magnetoencephalographic recordings of healthy subjects, and utilized excellent spatiotemporal accuracy to demonstrate significant across-condition differences in the time domain, along with indistinguishable neural correlates within-subject. In all participants, both words and pseudowords elicited activity in left perisylvian language areas, with words consistently activating these regions approximately 100 ms earlier than pseudowords. Considerable functional heterogeneity was also observed, and this might underlie the inconsistencies among previous studies. We conclude that the neural distinction in word/pseudoword processing is not in spatial localization, but is better conceptualized as a dynamic difference in processing time. (+info)
Category fluency test: effects of age, gender and education on total scores, clustering and switching in Brazilian Portuguese-speaking subjects.
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Verbal fluency tests are used as a measure of executive functions and language, and can also be used to evaluate semantic memory. We analyzed the influence of education, gender and age on scores in a verbal fluency test using the animal category, and on number of categories, clustering and switching. We examined 257 healthy participants (152 females and 105 males) with a mean age of 49.42 years (SD = 15.75) and having a mean educational level of 5.58 (SD = 4.25) years. We asked them to name as many animals as they could. Analysis of variance was performed to determine the effect of demographic variables. No significant effect of gender was observed for any of the measures. However, age seemed to influence the number of category changes, as expected for a sensitive frontal measure, after being controlled for the effect of education. Educational level had a statistically significant effect on all measures, except for clustering. Subject performance (mean number of animals named) according to schooling was: illiterates, 12.1; 1 to 4 years, 12.3; 5 to 8 years, 14.0; 9 to 11 years, 16.7, and more than 11 years, 17.8. We observed a decrease in performance in these five educational groups over time (more items recalled during the first 15 s, followed by a progressive reduction until the fourth interval). We conclude that education had the greatest effect on the category fluency test in this Brazilian sample. Therefore, we must take care in evaluating performance in lower educational subjects. (+info)
The effect of age and structural lesions on postictal language impairment.
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The duration of postictal language dysfunction following a temporal lobe complex partial seizure (TLCPS) is longer when the seizure originates in the dominant hemisphere. However, the effects of older age and the presence of a structural lesion ipsilateral to the area of origin of the seizure remain unknown. Postictal language delay (PILD) was analyzed in relation to age and presence of a structural lesion in 47 patients, 28 with dominant TLCPSs and 19 with nondominant TLCPSs (total 173 seizures). Mean ages of the groups were 32.5 years (range: 16-68) and 36.1 years (range: 21-50), respectively. Nonsclerotic structural lesions were found by magnetic resonance imaging in 13 patients, eight with seizures in the dominant hemisphere and five with seizures in the nondominant hemisphere. Age did not affect PILD regardless of the lateralization of the seizures. The presence of a structural lesion significantly prolonged PILD only in the patients with nondominant TLCPS (p = 0.019). In conclusion, the anatomical site of seizure onset may not be the only determinant of the nature of the postictal state. PILD can provide important information on seizure localization and spread. (+info)
Language-related activations in the left prefrontal regions are differentially modulated by age, proficiency, and task demands.
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It remains to be elucidated how cortical activations are modulated by factors of age, proficiency, and language task demands when mastering first language (L1) and a second language (L2). Using functional magnetic resonance imaging, we tested subjects aged 13 (the age 13 group) and 19 (the age 19 group), thereby comparing the cortical activations involved in past-tense verb identification with those involved in verb matching. We found that the activation in the dorsal triangular part of the left inferior frontal gyrus (IFG) was lower, corresponding to a higher proficiency in English (L2) in the older subjects, suggesting that the proficiency level plays a major role in the activation of this region during L2 acquisition. Moreover, the lower activation in the triangular and orbital parts of the left IFG (F3t/F3O) for the irregular past tense corresponding to a higher proficiency in L2, together with the nonsignificant activation for the regular past tense when its performance almost reached perfection for age 19, suggests that the modulation of the left F3t/F3O activation reflects language task demands for identifying correct past-tense forms. On the other hand, the left F3t/F3O activation in Japanese (L1) for age 13 was significantly greater than that for age 19, despite the matched performances in L1. These results suggest that the left IFG subserves language-specific functions that are critically required when mastering any language. (+info)
A study of the abilities in oral language comprehension of the Boston Diagnostic Aphasia Examination -- Portuguese version: a reference guide for the Brazilian population.
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We analyzed the performance of 162 normal subjects, subdivided into groups according to age and schooling, in the oral comprehension tasks of the Boston Diagnostic Aphasia Examination translated and adapted to Brazilian Portuguese to obtain a profile of performance for the Brazilian population, as well as cut-off scores for each task, and to determine the best combination of tasks that distinguish normal from aphasic subjects, as a guide for clinicians. The normal subjects were compared to 69 aphasics. Age alone influenced the performance in the designation of actions (subjects above 70 years showing the worst performance); schooling alone influenced the comprehension of forms, colors and numbers (subjects with less than four years of education showing a poorer performance). Both age and schooling influenced the performance in Body Part Identification (BPI) and Complex Ideational Material (CIM) with mean values of 70.5 +/- 3.3 (Word Discrimination, WD), 18.9 +/- 1.4 (BPI), 14.7 +/- 0.9 (Commands), and 10.3 +/- 1.7 (CIM) for the whole sample; the cut-off scores obtained were 65 (WD), 17.5 (BPI), 14 (Commands), and 9.5 (CIM) for the whole sample. Logistic regression showed that the combination of BPI + Commands + CIM was the most efficient in differentiating normal subjects from aphasics, with 72.5% sensitivity and 97.6% specificity. However, for low-education subjects, BPI and Commands were sufficient for this differentiation (75.7% sensitivity and 84.7% specificity). The main contribution of this study was to provide reference values that are far more representative of our population to be used by health professionals in Brazil, taking into account cultural differences. (+info)
Clinical, cognitive and anatomical evolution from nonfluent progressive aphasia to corticobasal syndrome: a case report.
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Recent clinical and pathological studies have suggested that frontotemporal lobar degeneration (FTLD) and corticobasal syndrome (CBS) show clinical and pathological overlap. We present four years of longitudinal clinical, cognitive and anatomical data in the case of a 56-year-old woman, AS, whose clinical picture evolved from FTLD to CBS. For the first three years, AS showed a progressive speech and language disorder compatible with a diagnosis of the nonfluent aphasia variant of FTLD. At year four, 10 years after her first symptom, AS developed the classical clinical signs of CBS, including alien limb phenomenon and dystonia. Voxel-based morphometry (VBM) applied to AS's four annual scans showed progression of atrophy from the inferior posterior frontal gyrus, to the left insula and finally to the medial frontal lobe. This case demonstrates the clinical overlap between FTLD and CBS and shows that the two can appear in the same patient at different stages of the disease in relation to the progression of anatomical damage. (+info)