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PubMed2006

A study of syntactic processing in aphasia II: neurological aspects.

This paper presents the results of a study of the effects of left hemisphere strokes on syntactically-based comprehension in aphasic patients. We studied 42 patients with aphasia secondary to left hemisphere strokes and 25 control subjects for the ability to assign and interpret three syntactic structures (passives, object extracted relative clauses, and reflexive pronouns) in enactment, sentence-picture matching and grammaticality judgment tasks. We measured accuracy, RT and self-paced listening times in SPM and GJ. We obtained magnetic resonance (MR) and 5-deoxyglucose positron emission tomography (FDG PET) data on 31 patients and 12 controls. The percent of selected regions of interest (ROIs) that was lesioned on MR and the mean normalized PET counts per voxel in ROIs were calculated. In regression analyses, lesion measures in both perisylvian and non-perisylvian ROIs predicted performance. Patients who performed at similar levels behaviorally had lesions of very different sizes, and patients with equivalent lesion sizes varied greatly in their level of performance. The data are consistent with a model in which the neural tissue that is responsible for the operations underlying sentence comprehension and syntactic processing is localized in different neural regions in different individuals.

Aged↗
PubMed2006

Non-fluent progressive aphasia: cerebral metabolic patterns and brain reserve.

Functional imaging studies suggest that brain reserve allows patients with Alzheimer's disease with more years of schooling to cope better with brain damage. No studies exist on patients with non-fluent progressive aphasia (NFPA). We aimed to explore metabolic patterns of patients with NFPA and to provide evidence for brain reserve in NFPA. 11 right-handed patients with NFPA and 16 age-matched controls underwent (18)F-FDG PET imaging. Scans of patients and controls were compared in SPM2. A linear regression analysis with glucose metabolism as dependent variable and years of schooling as the independent variable, adjusted for age, gender, and a total score of the CERAD neuropsychological battery was conducted. The NFPA group showed a hypometabolism of the left hemisphere including the middle frontal, and inferior temporal and angular gyri, and the bilateral caudate nuclei and thalami (p(corr)<0.05). The regression analysis revealed a significant inverse association between education and glucose metabolism in the left inferior temporal, parahippocampal, and supramarginal gyri (p(corr)<0.05). We conclude that brain reserve is also present in NFPA.

Age Distribution↗
PubMed2006

Acquired stuttering in a patient with Wernicke's aphasia.

We report a patient with aphasia caused by cerebral infarction in the left temporal, parietal and occipital lobes that was complicated by acquired stuttering (AS), which is an unusual association. Our findings indicated that Wernicke's area might be involved in the development of AS.

Aphasia, Wernicke↗
PubMed2005

Cerebellar activity switches hemispheres with cerebral recovery in aphasia.

The right postero-lateral cerebellum participates with the left frontal lobe in the selection and production of words. Using fMRI, we examined whether cerebellar activity switches hemispheres in parallel with recruitment of putative compensatory right homologous frontal regions in post-stroke aphasia. Re-examining the data of Blasi et al. [Blasi, V., Young, A. C., Tansy, A. P., Petersen, S. E., Snyder, A. Z., & Corbetta, M. (2002). Word retrieval learning modulates right frontal cortex in patients with left frontal damage. Neuron, 36(1), 159-170], we asked: (1) if activity in the right cerebellum was disrupted by a left frontal lesion, (2) if activity switched to the left cerebellum, and (3) if activity in the left cerebellum was modulated by learning, as was right frontal cortex. Fourteen age-matched controls and eight mildly aphasic stroke patients participated. Aphasic participants all had lesions due to unilateral left hemisphere stroke at or near Broca's area. Subjects silently performed a word stem completion task with either novel or repeated items. Activity in right cerebellum of aphasic individuals was minimal and was not modulated by learning, as for controls. However, we observed robust learning-related attenuation of the BOLD signal in the left postero-lateral cerebellum consistent with learning-related effects in right frontal cortex. These findings support the hypothesis that right frontal and left cerebellar circuits are likely to be functionally relevant to recovered/residual verbal function.

Adult↗
PubMed2006

Recovery from aphasia as a function of language therapy in an early bilingual patient demonstrated by fMRI.

Knowledge about the recovery of language functions in bilingual aphasic patients who suffer from left-hemispheric stroke is scarce. Here, we present the case of an early bilingual patient (German/French) with chronic aphasia. Functional magnetic resonance imaging (fMRI) was used to investigate neural correlates of language performance during an overt picture naming task in German and French (a) 32 months after stroke to assess differential recovery of both languages as a function of the preceding language therapy that was provided exclusively in German and (b) after additional short-term intensive (German) language training. At the first investigation behavioral performance confirmed selective recovery of German naming ability which was associated with increased functional brain activation compared to the French naming condition. Changes in behavioral performance and brain activation pattern as disclosed by fMRI after an additional experimental treatment were confined to the trained (German) language and indicate bilateral neuroplastic reorganization. No generalization to the untrained (French) language was observed. The present case results demonstrate use and/or training-dependent differential recovery of expressive language functions and an enhanced pattern of brain activation as a function of the rehabilitation efforts that were focussed exclusively on the patient's German language abilities.

Adult↗
PubMed2005

Mapping of temporal and parietal cortex in progressive nonfluent aphasia and Alzheimer's disease using chemical shift imaging, voxel-based morphometry and positron emission tomography.

Little and controversial evidence is available from neuroimaging studies in progressive nonfluent aphasia (PNA). The goal of this study was to combine information from different imaging modalities in PNA compared with Alzheimer's disease (AD). Chemical shift imaging (CSI), voxel-based morphometry (VBM) and fluorodeoxyglucose positron emission tomography (FDG-PET) were used in 5 PNA, 10 AD patients and 10 normal subjects. Group comparisons revealed left anterior lateral temporal abnormalities (BA20/21) in PNA using CSI, VBM and PET in comparison to normal subjects. AD patients showed more limited hypometabolism within the same area. In addition left lateral parietal (BA40) abnormalities were demonstrated in our PNA as well as our AD group using PET and VBM (AD group only). Combining information from all imaging modalities on a single case basis revealed pathology within the left anterior lateral temporal and lateral parietal lobe both in PNA and AD. PNA and AD patients differed significantly, however, with respect to the frequency of medial temporal lobe and posterior cingulate/precuneus involvement. Although our results might not be generalizable to all subgroups of PNA, we conclude that medial temporal and posterior cingulate/precuneus cortex pathology as assessed by CSI and VBM or PET distinguish PNA from AD, whereas lateral temporal and parietal areas are involved in both conditions.

Aged↗
PubMed2006

Primary progressive aphasia accompanied by environmental sound agnosia: a neuropsychological, MRI and PET study.

As part of the frontotemporal dementias, primary progressive aphasia (PPA) is typically characterized by nonfluent speech with paraphasias, but there is growing evidence that also a fluent variant of PPA exists. We describe a patient suffering from PPA who adds to the broad clinical spectrum of this disorder. Moreover, we report for the first time that PPA may be associated with severe impairment in meaningful nonverbal sound recognition (environmental sound agnosia). These neuropsychological findings were found to be associated with distinct focal alterations in functional and structural neuroimaging.

Aged↗
PubMed2006

Reversible nonfluent aphasia and left frontal hypoperfusion during topiramate treatment.

We report the case of a patient with complex partial seizures who developed a nonfluent aphasia when topiramate was added to his therapy. This emergent adverse effect appeared to be reversible, as language performance improved after discontinuation of topiramate. Interictal SPECT performed when the patient was aphasic revealed a focal perfusion reduction in the left lateral and mesial frontal cortex, which was no longer evident at a follow-up study after language recovery.

Anticonvulsants↗
PubMed2003

The residual calculation abilities of a patient with severe aphasia: evidence for a selective deficit of subtraction procedures.

We report the case study of a severe fluent aphasic patient, who showed relatively preserved numerical abilities. A detailed investigation of number processing indicated good numerical comprehension and a relative sparing of addition and subtraction abilities; on the other hand, multiplication and division were severely impaired. A further study of multi-digit operations showed that the patient's performance was characterized by a selective impairment of the borrowing procedure, in which she applied the so-called Smaller-from-Larger bug, typically observed in children learning to calculate. The present case provides further evidence for the dissociation between operations based on verbal sequences and on quantity manipulation, respectively impaired and preserved in patients with severe aphasia. Moreover, it provides evidence indicating that procedures may be dissociated from conceptual knowledge within a single arithmetical operation.

Aphasia↗
PubMed1997

Optic aphasia: evidence of the contribution of different neural systems to object and action naming.

Visual stimulus naming was studied in a 66-year-old male patient with optic aphasia subsequent to left occipito-temporal infarction. While having difficulty in naming objects perceived visually, he was able to name objects by viewing gestures illustrating their use, and to name actions shown in pictures. These results suggest that naming performance depends on the kind of stimulus that is visually presented (object vs. action). The present findings lend support to congnitive models which postulate the existence of visual and functional semantic systems.

Aged↗
PubMed2006

Broca's area and inflectional morphology: evidence from broca's aphasia and computer modeling.

In a series of articles Ullman (2001, 2004; Ullman et al., 1997) has proposed that regular inflection is critically subserved by Broca's area. This suggestion is motivated by the finding that English speaking Broca's aphasics show selective deficits with regular inflection. Here we argue that this proposal does not hold cross-linguistically but is based on a confound between inflectional suffix and regularity that is specific to the English language. We present data from two experimental studies of participle inflection with 13 German and 12 Dutch Broca's aphasics. None of these aphasic speakers are selectively impaired for regular inflection but instead most of them show selective deficits with irregular inflection. These data suggest that a selective regular deficit is not a characteristic of Broca's aphasia across languages, and that Broca's area is not critically involved in regular inflection. To investigate the nature and localization of the processes underlying inflection we present a connectionist neural network model that accounts for the deficits of the German aphasic speakers. The model implements the view that the inflection of all verb types is based on a single mechanism with multiple representations that emerge from experience-dependent brain development. We show that global damage to this model results in a selective deficit for irregular inflection that is comparable to that of the German aphasic speakers. This finding suggests that a selective impairment of irregular participles as observed by German and Dutch aphasic speakers does not presuppose two distinctly localized mechanisms or processes that can be selectively affected by brain damage.

Adult↗
PubMed2000

Acalculia, aphasia and spatial disorders in left and right brain-damaged patients.

The paper reports the performance of 50 left- and 26 vascular right-brain-damaged (LBD, RBD) patients in the EC301 Calculation Battery, which explores different aspects of number and calculation processing. All patients underwent a comprehensive neuropsychological testing that also included evaluation for the presence and type of aphasia in LBD patients, and of spatial disorders in RBD patients. LBD were subdivided in three groups: non-aphasic (NA), Broca and Wernicke aphasics. Results indicate that language and calculation disorders can dissociate. The relationship between spatial and calculation disorders in RBD patients is less clear. No significant difference was found between Broca and Wernicke aphasics, nor between NA and RBD patients. In the transcoding tasks (reading or writing to dictation numbers and number words, for instance) syntactic errors were the most frequent type of errors in all groups. They were also present when neither the input nor the required response was in the Arabic code, and a word-by-word strategy could have been used to read the number word or write a spoken number in the orthographic code.

Adult↗
PubMed2001

Prearticulatory and postarticulatory self-monitoring in Broca's aphasia.

The present study examined to what extent patients with Broca's aphasia and healthy controls rely upon prearticulatory and postarticulatory monitoring processes for detecting and repairing errors in speech production. Monitoring skills were investigated in a speaking situation with normal auditory feedback, a speaking situation with white noise, and a situation in which errors had to be detected in other-produced speech. The results demonstrated that the Broca's aphasics repaired a lower percentage of errors than the controls in the situation with normal auditory feedback, whereas their performance in the noise-masked condition was comparable. In contrast to the controls, the aphasics did not suffer from the presence of white noise. In addition, the proportion of covert repairs was higher for the Broca's aphasics than for the healthy controls. These findings indicate that Broca's aphasics concentrate primarily on prearticulatory monitoring. Possible explanations for this strong reliance on prearticulatory monitoring processes are discussed.

Adult↗
PubMed1998

Optic aphasia with pure alexia: a mild form of visual associative agnosia? A case study.

A single-case study is reported of a naming disorder selective to the visual modality. The patient showed intact access to structural knowledge of objects and letters, but impaired access to complete semantic knowledge of objects and alphabetical knowledge of letters from visual input. The impairment was most striking when the patient had to discriminate between semantically similar objects or within a given symbolic repertoire, i.e. letters. The co-occurrence of a partial deficit of visual recognition for objects and for letters indicated features of optic aphasia and pure alexia. This symmetric performance between object and letter processing may also constitute a mild form of visual associative agnosia.

Aged↗
PubMed2004

Adult crossed aphasia in dextrals revisited.

The clinical study of crossed aphasia in dextrals (CAD) may shed light on the discreteness and modularity of several cognitive functions, such as language, gestures and visual spatial abilities, with respect to hemispheric lateralisation. Since 1975 over 180 cases have been described, employing, however, different criteria of assessment and classification. The purpose of this paper is to review them and to propose a set of diagnostic criteria that may be useful to single out a series of reliable CAD cases on which research can be safely carried out. A detailed analysis of such series is dealt with in terms of a number of characteristics concerning both the language disorder and the associated nonverbal cognitive impairments.

Adult↗
PubMed1991

Crossed anomic aphasia: mild naming deficits following right brain damage in a dextral patient.

A detailed case study is reported of crossed aphasia (CA) in a dextral patient, bearing upon such controversial issues as intrahemispheric localisation of language function and hemispheric reversal of nonverbal function. DA, a man aged 37, developed a mild naming problem due to right temporal lobe haematoma. Apart from a mild acquired stutter, his continuous speech was fluent and had a normal proportion of open to closed class lexical items. His naming deficit appears to originate in the 'blocking' or 'disconnection' of the phonological lexicon: he could usually give a functional definition of un-named items and retrieve them with the help of a phonemic cue. Lexical retrieval appears his only language deficit, as he had no comprehension or phonological discrimination deficits. DA showed no visuo-spatial or auditory-nonverbal deficits, suggesting the complete reversal of hemispheric specialisation.

Adult↗
PubMed1991

Brain activation during a linguistic task in conduction aphasia.

In order to investigate functional cortical reorganization during recovery from conduction aphasia, regional cerebral blood flows (rCBF) were measured by the two-dimensional 133 Xenon inhalation method in ten stroke patients. rCBF measurements were performed at rest and during the performance of a linguistic task, one month and three months after onset. The analysis of flow changes from rest to test condition indicates an increasing contribution of the right hemisphere as time goes on. The absence of flow increase in Broca's region suggests that this region is definitively disconnected from posterior language "centers" by the arcuate fasciculus lesion.

Aged↗
PubMed1992

Visual associative agnosia and optic aphasia. A single case study and a review of the syndromes.

The case is presented of a patient who showed visual naming disturbances caused by a left occipital infarction. His performance on tests of visual naming, of recognition not requiring a verbal response, and of verbal-visual matching demonstrated a wide range of qualitatively different errors, including complete inability to recognize the object, access to partial semantic knowledge, and mere name finding difficulty. On the basis of the present case and of a review of the recent literature, the clinical distinction between visual associative agnosia and optic aphasia and the relation of these disorders with the anatomical site of lesion are discussed.

Agnosia↗