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Sex-linked left lateralized central processor for hierarchically-structured material? Evidence from Broca's aphasia.

Based on a study with seven nonfluent aphasics, Grossman (Neuropsychologia 18, 299-308, 1980) advanced the 'central processor' claim that the mental representation of hierarchical linguistic structure is functionally equivalent to processing hierarchically-structured, nonlinguistic forms. Grossman reported that both abilities are compromised in Broca's aphasia. We attempted to replicate this effect with eight nonfluent aphasics using essentially the same task requiring the reconstruction from memory of stick designs. With the addition of controls for post-stroke interval, responding hand and gender, only the female aphasics had difficulty executing the hierarchical arrangement of visual-spatial materials. This sex difference disputes the strong form of the central processor hypothesis and supports the view that females may be more likely to possess partial noncomplementarity of specialization (dependence on the same hemisphere for selective language and spatial functions).

Adult↗

A signal processing component to Broca's aphasia functor deficits.

We conducted a modified replication of K. M. Heilman and R. J. Scholes [Cortex 12, 258-265, 1976] test of functor comprehension in aphasia, controlling the acoustic dimensions of the key function words: 9 Broca patients heard 4 sentence pairs differing only in the post-verb placement of the. They made forced choices between 4 line drawings: one which depicted the correct action, one which depicted the action of the other member in the pair, and two which contained depictions of different figures and actions altogether. Each of the 8 sentences was played in 2 conditions: one with NORMAL intonation, and another with an acoustically more SALIENT post-verbal the. Both of Heilman and Scholes' principal results were successfully replicated, and a SALIENT effect was also discovered, supporting a signal processing component to the Broca syndrome functor deficit.

Aphasia↗

Contrasting cases of Italian agrammatic aphasia without comprehension disorder.

Two patients with agrammatic speech and unimpaired comprehension are presented and contrasted. Case 1 had an infarction involving precentral gyrus, subjacent white matter, and posterior and superior aspects of the insula, largely sparing Broca's area. His speech was slow and dysarthric, consisting of short disconnected phrases with some omission of lexical verbs. Case 2 had an unusual transient aphasia of acute onset without hemiplegia; speech rate, articulation, and sentence length and complexity appeared normal. Both patients tended to omit function words and finite verb inflections, but Case 2 did so much more than did Case 1. Neither patient showed impairment in any other area of language performance. Tentatively, Case 2 is described as being more morphologically impaired but less syntactically impaired than Case 1, while neither has damage to a central language processor.

Adult↗

Self-monitoring behavior in a case of severe auditory agnosia with aphasia.

This case report describes an unusual combination of speech and language deficits secondary to bilateral infarctions in a 62-year-old woman. The patient was administered an extensive series of speech, language, and audiologic tests and was found to exhibit a fluent aphasia in which reading and writing were extremely well preserved in comparison to auditory comprehension and oral expression, and a severe auditory agnosia. In spite of her auditory processing deficits, the patient exhibited unexpected self-monitoring ability and the capacity to form acoustic images on visual tasks. The manner in which she corrected and attempted to correct her phonemic errors, while ignoring semantic errors, suggests that different mechanisms may underlie the monitoring of these errors.

Agnosia↗

Effects of hypnosis and imagery training on naming behavior in aphasia.

The effects of hypnosis and imagery training on the naming behavior of three subjects with Broca's aphasia were investigated using a multiple baseline design across subjects. Treatment consisted of the induction of hypnosis, followed by guided imagery focused on the physical and functional attributes of stimulus objects. Measures of naming ability on both trained and untrained items were taken at baseline, after every training session, and a few hours after training each day. Measures were also taken of imagery ability, hypnotic susceptibility, and psychological state. Results indicated that treatment facilitated improvement in naming ability, over baseline level, for two subjects. In the case of the third subject, the verbal label was incorporated into the imagery procedure following 10 training sessions. Subsequently, this subject's naming behavior improved over baseline level. The results are discussed in terms of current theory and research in neuropsychology and cognitive psychology.

Anomia↗

Transcortical sensory aphasia: evidence for subtypes.

Impaired auditory comprehension and fluent but semantically empty speech in conjunction with preserved repetition characterize the syndrome of transcortical sensory aphasia (TSA). Repetition, however, may be mediated by at least two distinct processes--a lexical process that may involve the recognition and subsequent activation of discrete stored word representations and a nonlexical process that involves phonologic decoding and immediate phonologic encoding from immediate memory. We investigated the spontaneous speech, reading, and tendency to recognize and spontaneously correct syntactic errors in four patients with TSA: this analysis suggests there are two subtypes of TSA. We contend that in one subtype both the lexical and direct repetition (or speech production) mechanisms are preserved, but in the second subtype the lexical mechanism is disrupted and repetition is mediated by the nonlexical mechanism.

Adult↗

Comprehension of sentence structure in anomic and conduction aphasia.

Picture-pointing auditory and reading comprehension tests were administered to anomic and conduction aphasics. Subjects responded to active sentences of the present progressive form. The possible errors which a subject could make on these experimental tasks included failure to correctly interpret noun order, number, or lexical meaning. Both groups made significantly more correct responses than error responses. Of their error responses, noun-order errors significantly exceeded number and lexical errors for which no differences were observed. When compared with results previously obtained for agrammatic Broca's aphasics, no differences in the pattern of errors were identified. These results are discussed relative to current theories of syntactic processing and for the mechanisms which account for these syntactic comprehension deficits following aphasia.

Adolescent↗

Dysprosody in Broca's aphasia: a case study.

A detailed acoustic analysis of timing, intensity, and fundamental frequency (F0) at different levels of linguistic structure was conducted on the speech output of a Broca's aphasic who was a native speaker of Thai. Timing was measured with respect to syllables, phrases, and sentences in connected speech. Intensity variation at the sentence level was measured in connected speech. F0 variation associated with the five Thai tones was measured in both isolated words and connected speech. Results indicated that timing was differentially impaired depending upon complexity of articulatory gesture and size of the linguistic structure. Timing, as well as intensity, was aberrant at the sentence level. In contrast, F0 contours of the five tones were spared at all levels of linguistic structure. Findings are interpreted to support the view that dysprosody in Broca's aphasia is more applicable to speech timing than to F0.

Aphasia↗

Communicative skills in chronic and severe nonfluent aphasia.

A diagnostic tool was developed for the investigation of communicative skills in nonfluent aphasic patients suffering from moderate or severe language deficits. Communicative skills and neurolinguistic deficits were assessed in 20 patients suffering from Broca's or global aphasia. Comparative data analysis revealed remarkably low correlations between communicative and neurolinguistic deficits. In nonfluent aphasic patients with severe linguistic impairment communicative abilities and non- and paralinguistic compensatory efforts and skills accounted for their efficient performance.

Adult↗

Syntactic priming effects in aphasia: an investigation of local syntactic dependencies.

This study explored on-line processing of local syntactic dependencies in normal subjects and in Broca's and Wernicke's aphasics using a lexical decision paradigm. In addition, subjects performed a grammatically judgement task on the real word pairs used in the lexical decision tasks. Results of two experiments for normal subjects indicated different syntactic priming effects as a function of the type of local syntactic dependency. Word pairs that formed a single constituent phrase, i.e., a verb phrase, showed both facilitory and inhibitory effects, whereas word pairs that reflected local syntactic dependencies across a phrase boundary, i.e., pronoun verb, showed only inhibitory effects. Broca's aphasics failed to show facilitory effects when presented with word pairs forming a single constituent phrase but, similar to normals, did show inhibition when presented with word pairs that reflected local syntactic dependencies across a phrase boundary. In contrast, Wernicke's aphasics failed to show inhibitory effects in both experiments. The implications of these results for theories of language processing deficits in aphasia are considered.

Adult↗

The classifier problem in Chinese aphasia.

In recent years, research on the relationship between brain organization and language processing has benefited tremendously from cross-linguistic comparisons of language disorders among different types of aphasic patients. Results from these cross-linguistic studies have shown that the same aphasic syndromes often look very different from one language to another, suggesting that language-specific knowledge is largely preserved in Broca's and Wernicke's aphasics. In this paper, Chinese aphasic patients were examined with respect to their (in)ability to use classifiers in a noun phrase. The Chinese language, in addition to its lack of verb conjugation and an absence of noun declension, is exceptional in yet another respect: articles, numerals, and other such modifiers cannot directly precede their associated nouns, there has to be an intervening morpheme called a classifier. The appropriate usage of nominal classifiers is considered to be one of the most difficult aspects of Chinese grammar. Our examination of Chinese aphasic patients revealed two essential points. First, Chinese aphasic patients experience difficulty in the production of nominal classifiers, committing a significant number of errors of omission and/or substitution. Second, two different kinds of substitution errors are observed in Broca's and Wernicke's patients, and the detailed analysis of the difference demands a rethinking of the distinction between agrammatism and paragrammatism. The result adds to a growing body of evidence suggesting that grammar is impaired in fluent as well as nonfluent aphasia.

Aphasia, Broca↗

Sentence comprehension in aphasia in two clear case-marking languages.

Studies of aphasia in Indo-European languages point to a selective vulnerability of morphological case marking in sentence comprehension. However, in case-marking languages such as German and Serbo-Croatian, the use of case marking to express formal grammatical gender diminishes the clarity of grammatical role marking. In Hungarian and Turkish, there are simple and reliable markings for the direct object. These markings are not linked to grammatical gender. Compared to Hungarian, the Turkish accusative marking is somewhat lower in availability, but somewhat higher in detectability. The processing of these cues by aphasics was tested using the design of MacWhinney, Pléh, and Bates (1985. Cognitive Psychology, 17, 178-209). Simple sentences with two nouns and one transitive verb were read to Broca's and Wernicke's aphasics, anomics, and control subjects in both Turkey and Hungary. The main effect of case marking was extremely strong. However, this was not true for all groups. The aphasics used the case cue far less than the normals, with the Hungarian Wernicke's group showing the greatest loss. Word order variations were largely ignored in all groups whenever the case-marking cue was present. When case marking was absent, Turkish subjects had a clear SOV interpretation for NNV sentences and Hungarians had a clear SVO interpretation for NVN sentences, in accord with basic patterns in their languages. When there was a contrast between the animacy of the two nouns, subjects choose the animate nouns significantly more often. The effect of animacy was particularly strong in Turkish, in accord with basic facts of Turkish grammar. In Hungarian, VNN sentences without case marking were interpreted as VOS when the first noun was inanimate. In Turkish, VNN sentences without case marking were often interpreted as VSO. In general, the aphasic subjects showed a clear preservation of virtually all aspects of their native languages, albeit in a much noisier form. Despite the high reliability of the case-marking cue, it was damaged more than the word order cue in English subjects. The near-chance processing of the case cue by the Wernicke's aphasics in Hungarian can probably be attributed to the relatively greater difficulty involved in detecting the Hungarian accusative suffix.

Anomia↗

Selective impairment of grammatical morphology due to induced stress in normal listeners: implications for aphasia.

The traditional clinical picture for English nonfluent aphasics has generally presented the deficit as one of total loss of control over grammatical morphology, with some sparing of word order. This is at odds with recent research involving nonfluent aphasic speakers of highly inflected languages, which has shown that agrammatic performance is characterized by morphological substitution rather than omission errors. If the deficit associated with focal brain damage cannot be adequately accounted for in syndrome-specific ways, we may need to look for language-specific processing explanations. One such explanation has to do with language-specific response to global processing difficulty. The current experiment is designed to study the effects of a stress-related limitation on morphological processing. Normal speakers of a language with a relatively rich morphological system (German) are compared with those of a comparatively impoverished system (English) on different forms of a sentence comprehension task. In one form, "clean" stimuli permit full reliance on all available cues to meaning in each language. In another test, a low-level noise mask partially obscured the stimulus sentences. English speakers, who rely almost exclusively on word order cues, were not affected by the noise manipulation. German speakers relied heavily on morphological and semantic information rather than on word order under "clean" conditions. However, under noise Germans made significantly less use of grammatical morphology, with a trend toward compensatory reliance on word order. The results indicate that a global reduction in processing capacity can affect some aspects of language more than others and suggest that such factors must be taken into account in trying to understand specific impairment of morphology in aphasia.

Adult↗

Processing of disyllabic compound words in Chinese aphasia: evidence for the processing limitations account.

The current study addresses the debate between so-called 'structural' and 'processing limitation' accounts of aphasia, i.e., whether language impairments reflect the 'loss' of linguistic knowledge or its representations, or instead reflect a limitation in processing resources. Confrontation-naming task and category-judgment tasks were used to examine and compare the performance of non-fluent and fluent aphasics on different compound types of nouns and verbs. We demonstrate that aphasic patients' performance is modulated by the canonicity of the particular compound type, a result that holds true even for the category in which patients show a 'selective category deficit.' These findings weigh against the 'loss' of linguistic representations as the underlying cause of noun-verb deficits, instead supporting a 'processing limitations' approach.

Adult↗

Fluent versus nonfluent primary progressive aphasia: a comparison of clinical and functional neuroimaging features.

To better characterize fluent and nonfluent variants of primary progressive aphasia (PPA). Although investigators have recognized both fluent and nonfluent patients with PPA, the clinical and neuroimaging features of these variants have not been fully defined. We present clinical and neuropsychological data on 47 PPA patients comparing the fluent (n=21) and nonfluent (n=26) subjects. We further compared language features with PET/SPECT data available on 39 of these patients. Compared to the nonfluent PPA patients, those with fluent PPA had greater impairment of confrontational naming and loss of single word comprehension. They also exhibited semantic paraphasic errors and loss of single word comprehension. Patients with nonfluent PPA were more likely to be female, were more often dysarthric, and exhibited phonological speech errors in the absence of semantic errors. No significant differences were seen with regard to left hemisphere abnormalities, suggesting that both variants result from mechanisms that overlap frontal, temporal, and parietal regions. Of the language measures, only semantic paraphasias were strongly localized, in this case to the left temporal lobe. Fluent and nonfluent forms of PPA are clinically distinguishable by letter fluency, single word comprehension, object naming, and types of paraphasic errors. Nevertheless, there is a large amount of overlap between dysfunctional anatomic regions associated with these syndromes.

Aged↗

Interpretation of pronouns in VP-ellipsis constructions in Dutch Broca's and Wernicke's aphasia.

In this paper, we investigate the ability of Dutch agrammatic Broca's and Wernicke's aphasics to assign reference to possessive pronouns in elided VP constructions. The assumption is that the comprehension problems in these two populations have different sources that are revealed in distinct patterns of responses. The focus is primarily on the performance of the agrammatic group whose errors in comprehension are not viewed as a consequence of a breakdown of grammatical knowledge but as a result of limited processing resources (for an overview see Grodzinsky, 2000). The results of the present study provide evidence for the psycholinguistic reality of the economy hierarchy as proposed in the Primitives of Binding (Reuland, 2001). According to the economy hierarchy proposed for the non-brain-damaged, the more economical semantic dependencies are preferred over the costlier discourse dependencies. This hierarchy is reflected in agrammatic aphasia where the semantic dependencies are available on time and preferred over the discourse dependences that are not available on time as a result of the lack of processing resources with consequences for comprehension.

Adult↗

When ottoman is easier than chair: an inverse frequency effect in jargon aphasia.

This paper presents evidence of an inverse frequency effect in jargon aphasia. The subject (JP) showed a pre-disposition for low frequency word production on a range of tasks, including picture naming, sentence completion and naming in categories. Her real word errors were also striking, in that these tended to be lower in frequency than the target. Reading data suggested that the inverse frequency effect was present only when production was semantically mediated. It was therefore hypothesised that the effect was at least partly due to the semantic characteristics of low frequency items. Some support for this was obtained from a comprehension task showing that JP's understanding of low frequency terms, which she often produced as errors, was superior to her understanding of high frequency terms. Possible explanations for these findings are considered.

Aged↗

The effects of emotionality on auditory comprehension in aphasia.

Twelve exclusively left brain damaged aphasic male patients (8 global, 3 Wernicke and 1 mixed transcortical) were administered an auditory single word discrimination task. The stimuli were 7 emotional action words, 7 nonemotional action words, 7 emotional object names and 7 nonemotional object names. Results showed significantly better performance on emotional words versus nonemotional words. Implications for assessment and treatment of aphasia are discussed.

Adult↗