Confrontation naming impairment in dementia

In tone languages pitch variations (tones) serve to distinguish the lexical meanings of words. This study was conducted to examine the extent and nature of impairment in the perception of tones by aphasic patients who were monolingual speakers of Thai, a tone language which has five contrastive tones (mid, low, falling, high, rising). Six subjects participated in the study: two Broca aphasics, one transcortical motor aphasic, one conduction aphasic, one right brain-damaged nonaphasic, and one normal control. Three sets of stimuli (two real-speech, one synthetic-speech) were presented for identification, each set containing five Thai words minimally distinguished by tone. Results of the perception tests indicated that the performance of all four left brain-damaged aphasics differed significantly from that of the normal control, while the performance of the right brain-damaged nonaphasic did not. The normal performance of the right brain-damaged nonaphasic patient on this tone identification task suggests that deficits in the perception of tone exhibited by left brain-damaged patients can be attributed specifically to pathology in the language dominant hemisphere rather than to a general brain-damage effect. No difference in performance among the left brain-damaged patients could be attributed to a specific type of aphasic syndrome. The pattern of tonal confusions of the aphasics in comparison to that of normals suggests that their deficit is primarily quantitative rather than qualitative. Although two (mid, low) of the five tones accounted for a large percentage of the aphasics' errors, no uniform rank order of tones in terms of identifiability could be established across aphasic subjects, which suggests that their deficit is general to all five tones rather than selective to individual tones.     

Speech production mechanisms in aphasia: A delayed auditory feedback study

Data collected from a delayed auditory feedback (DAF) study conducted by F. Boller, P. B. Vrtunski, Y. Kim, and J. L. Mack (1978, Cortex, 14, 212–226) were reanalyzed to determine if speech quality measures which were significantly affected during DAF could be operationalized and to ascertain which type of errors are responsible for the judgement. A second goal of this study was to determine if Conduction aphasics were relatively spared under conditions of DAF, as has been shown in previous studies. Twenty aphasic patients and ten controls were presented with several speech production tasks under two delay conditions and two simultaneous feedback conditions. Results indicated that only the category of vowel length produced a significant number of errors, suggesting that DAF affects articulatory implementation. Conduction aphasics showed the least effect of all the groups. These results support Wernicke's and Geschwind's model, in which Conduction aphasics have a disconnection between the sensory and motor images of words. In contrast, Broca's aphasics were the most affected group under DAF, suggesting that a major component of their disorder is phonetic in nature.     

Some aspects of language comprehension in anterior aphasia

The competency of language comprehension was evaluated in three groups: anterior aphasics, posterior aphasics, and normal control subjects. Test material was divided into two sentence groups (Fill in the Blank and True/False) emphasizing either (1) semantic, “real world,” identity words or (2) syntactic, relational words, and one paragraph interpretation task. Matching auditory and visual (written) presentations were given. The control subjects performed almost flawlessly but many errors were made by each aphasia group. Qualitative study revealed a marked difference in the comprehension problem of the two groups. The anterior aphasic group performed well on semantically weighted sentences but made errors on syntactically weighted material, regardless of mode of presentation. In contrast, the posterior aphasics made almost the same number of errors on both types of material, regardless of mode of presentation. These findings support the concept of defective language comprehension in anterior aphasia and further suggest that the defect centers on the syntactical structures which are also poorly handled in expressive output.     

The effect of pictorial context on sentence memory in Broca's and Wernicke's aphasia

Eighteen aphasic patients (8 Broca's and 10 Wernicke's aphasics), 11 right hemisphere damaged patients and 12 normal subjects were tested to assess the effect of pictorial context on verbal memory with a sentence recognition task. The subjects were read aloud a stimulus sentence describing a simple event and simultaneously shown a picture congruent or incongruent with the sentence. Immediately following or after an interval of 30 sec, the subjects were read aloud a second sentence and asked to judge whether this sentence was the same or different from the stimulus sentence. The results indicated that verbal memory was better retained in supportive situations than in distracting situations, and that this contextual effect was greater in aphasic patients than in any of the other groups. Verbal memory declined rapidly after an interval in aphasic patients, but not in normal subjects. The Broca's and the Wernicke's aphasics demonstrated different performance patterns when semantic analysis of sentences was critical.     

A study of repetition in aphasic patients

The ability of the aphasic patient to repeat a message is a capacity of considerable diagnostic value. While it is well known that certain aphasic groups (e.g., transcortical aphasics) repeat better than other groups (e.g., conduction aphasics), possible qualitative differences among the groups have not been subjected to analysis. To secure information on repetition profiles in various aphasic subgroups, a test consisting of 11 types of items, presented under conditions of both immediate and delayed recall, was administered to eight groups of aphasic patients. The results documented a significant difference across aphasic groups, one related to site of lesion but not to severity of comprehension defect. Performance proved to be a joint product of the length and the meaningfulness of the stimulus items. The delayed condition aided Broca's aphasics and impeded anomic aphasics; in addition, nonsense syllables proved to be easier on immediate recall, while meaningful stimuli, particularly those which were number related, were relatively easier on delayed recall. Finally, sound errors were more likely to be made by Broca's and “mixed anterior” aphasics, while meaning errors were particularly prominent among conduction aphasics. These results are discussed in terms of the mechanisms which may mediate repetition in aphasic patients.     

Comparison of the performances of a fluent and a nonfluent aphasic on a pantomimic referential task

The pantomimic performances of a typical Broca's (nonfluent) and Wernicke's (fluent) aphasic were compared with each other and with four normal control subjects on a simple task of nonverbal referential communication. Both aphasic subjects demonstrated only about 50% accuracy in their pantomimic communication. Also, measures were obtained of the motoric fluency of the pantomimes of all subjects and comparisons were made between the fluent and nonfluent aphasics. These measures demonstrated distinct differences in the fluency patterns of the pantomimes of the two aphasic subjects similar to the differences in speech fluency which distinguish and characterize these two types of aphasia; that is, the fluent aphasic pantomimed fluently and like the control subjects and the nonfluent aphasic pantomimed nonfluently. The quantitative and qualitative similarities in the fluency patterns of the speech and the pantomimic behaviors of the aphasic subjects are discussed in terms of their implications for a definition of aphasia.     

The appreciation of antonymic contrasts in aphasia

To secure information on the ability of aphasic patients to comprehend antonymic relations, the kinds of confusions typically made, and the extent to which antonymic sensitivity depends upon mode of presentation and task demands, three linguistic and nonlinguistic tests were administered to aphasic patients, right hemisphere-damaged patients, and non-neurological controls. Although difficulty with antonymous relations was found among all the organic patients, the kinds of problems evidenced and the relative profile of difficulties differed across populations. Among the principal findings were the generally preserved sensitivity to antonymy found among anterior (particularly Broca's) aphasics; a surprising insensitivity to antonymy and a preference for synonyms, found among right hemisphere patients, particularly on the nonlinguistic tasks; a relative preservation of sensitivity to antonymy on nonlinguistic tasks, coupled with a loss of such sensitivity on linguistic tasks, found among posterior (particularly Wernicke's) aphasics; a proclivity toward stereotypical correct responses among the organic patients; and an absolutely worse performance by right hemisphere patients on tasks involving antonymic relations in pictures and abstract designs.     

The conceptual structure of aphasic and schizophrenic patients in a nonverbal sorting task

Hierarchical and overlapping cluster methods were applied to the sortings of aphasic, nonaphasic brain-damaged, schizophrenic, and normal subjects presented with 30 pictures of animals. The hierarchical structure solutions were most diffuse for the groups of the schizophrenics and the fluent aphasics. The structure for the nonfluent aphasics showed more clarity, but was also deviant from the structures of the normals and the brain-damaged without aphasia. Fluent aphasics but not nonfluent aphasics tended to sort pictures which they could not name into smaller groups. For the nonfluent aphasics, there was a significant correlation between the commonality of the sortings and the severity of aphasic disturbances as measured by the Token Test. The relationship between conceptual disorganization and language impairment seems to be functionally different for fluent and nonfluent aphasics.This research was supported by a research grant from the Deutsche Forschungsgemeinschaft.     

The processing of negative sentences in fluent aphasics: semantic and pragmatic aspects.

This paper examines the processing of negative sentences with respect to their truth value in fluent aphasic subjects. Three groups of 25 subjects each (men and women) were studied: the first group consisted of fluent aphasics, the second consisted of right temporal lobe-damaged subjects, and the third of normal subjects. An experiment of sentence verification was carried out. A quantitative study of reaction time (RT) and a qualitative study of the types of answers were carried out. The results show that the fluent aphasics were impaired in their logical-semantic processing of negative sentences and showed a predilection for the affirmative in answering strategies. The right temporal lobe-damaged subjects showed differences only in respect to the normal subjects in the RT, but not in answering strategies. The results suggest that in Wernicke's Aphasics there is a tendency to substitute a type of contextual-pragmatic processing for the logical-semantic processing.     

An Acoustic Analysis of Rate of Speech Effects on Vowel Production in Aphasia

The present investigation examined the production of tense and lax vowel duration differences at two speaking rates in the speech of 10 nonfluent aphasics, 8 fluent aphasics, and 10 normal control subjects. Subjects produced four repetitions of each of the vowels [i e æ o u I ε υ Λ] at each speaking rate. Acoustic analyses revealed that subjects in all three groups were able to manipulate overall rate of speech. In addition, normal controls and fluent aphasic subjects produced vowels under the fast rate condition which were significantly shorter than those under the slow rate condition. Despite a change in overall speaking rate, the nonfluent aphasics did not exhibit a significant difference in vowel duration at the two rates of speech, suggesting a deficit in the implementation of this temporal parameter. Both normal controls and fluent aphasic patients produced nonoverlapping distributions of tense and lax vowels at both speaking rates. In contrast, the nonfluent aphasics demonstrated a great deal of overlap in the distribution of tense and lax vowel durations at the fast rate. Results are discussed in relation to the nature of the speech production deficits in nonfluent and fluent aphasic patients.     

An investigation of body part as object (BPO) responses in normal and brain-damaged adults

A test of simple pantomime was administered to three groups of adults and comparisons were made across groups of the incidence of subjects who exhibited body part as object (BPO) responses and of the mean frequency of occurrence of BPO in each group. The three groups were left-hemisphere-damaged aphasics (N = 28), right-hemisphere-damaged (N = 24), and normal controls (N = 28). The results indicated no significant differences among groups on the BPO measures. Also, to test the strength of association between the frequency of occurrence of BPO and measures of limb apraxia and severity of aphasia for the left-hemisphere-damaged aphasic group, correlation coefficients were obtained. The correlations were low and nonsignificant. The results of this investigation do not support the common clinical assumption that the occurrence of BPO during the performance of simple pantomimes is pathognomic for left-hemisphere pathology or associated with limb apraxia.     

A study of spelling in aphasia

To secure systematic information on spelling abilities following damage to the dominant hemisphere, a test probing performance in three modalities of response was administered to a group of aphasic patients. Except for a predictable deficit among anterior aphasics in oral spelling, anterior and posterior aphasics exhibited comparable performances on the measures of spelling. However, anterior and posterior aphasics differed from one another on the kinds of words they most accurately spelled, the errors they were prone to make, and certain strategies which they characteristically adopted. These results suggest two alternative approaches to spelling: one approach, common in posterior aphasics, entails choosing letter combinations on the basis of their customary sounds; a second approach, common among anterior aphasics, appears to rely on a partially preserved image of the word's appearance.     

Cerebral dominance in aphasia recovery.

This investigation studied the patterns of ear preference of a group of 25 aphasic adults through the administration of two verbal dichotic tests and retests over a 2-month interval of time. These dichotic tests were a Dichotic Digits Test (DDT) and a Dichotic Animal Names Test (DANT). Schuell's short test of aphasia was given twice over this interval to assess language recovery. Results indicated that as aphasics improve in language, cerebral dominance becomes more firmly established in the right cerebral hemisphere. The data in this study tend to support a dominance shift hypothesis in the recovery of language after aphasia.     

Compensation for Jaw Fixation by Aphasic Patients

The ability to compensate for fixation of the jaw by a bite block was investigated in 6 nonfluent aphasics, 6 fluent aphasics, and 10 normal control subjects. Acoustic analyses of the vowels [i u a æ] and fricatives [s s] revealed substantial but incomplete compensation for the perturbation in all three subject groups. Perceptual identification scores and quality ratings by naive and phonetically trained listeners indicated poorer identification of the high vowels [i u] under compensatory conditions relative to normal production. Of particular interest was the fact that all three groups of subjects exhibited similar patterns of results. The findings suggest that any deficit in speech motor programming demonstrated by the nonfluent aphasic patients did not affect compensatory abilities. Results are discussed with respect to normal speech adaptation skills and the nature of articulatory breakdown in nonfluent aphasia.     

Perception and production of tone in aphasia

An acoustical and perceptual study of lexical tone was conducted to evaluate the extent and nature of tonal disruption in aphasia. The language under investigation was Thai, a tone language which has five lexical tones--mid, low, falling, high, and rising. Subjects included six left brain-damaged aphasics (two Broca's, one transcortical motor, one global, one conduction, one Wernicke), one right brain-damaged nonaphasic, one cerebellar dysarthric, and five normals. High-quality tape recordings of each subject's productions of a minimal set of five, monosyllabic Thai words were presented to 10 adult Thai listeners for identification. Results from the phonemic identification tests indicated that tone production is relatively spared in aphasic patients with unilateral left hemisphere lesions. The performance of the global aphasic, however, was considerably below normal. Patterns of tonal confusions further revealed that the performance of all aphasics, except the global, differed from that of normal speakers primarily in degree rather than in kind. Tonal contrasts were signaled at a high level of proficiency by the right brain-damaged and dysarthric patients. Acoustical analysis revealed that F0 contours associated with the five tones for all aphasics, except the global, were similar in overall shape as well as position in the tone space to those of normals. F0 contours for the right brain-damaged patient and the dysarthric also generally agreed with those of normals in terms of shape and position. F0 ranges of both aphasic and nonaphasic brain-damaged speakers were generally larger than those of normals for all five tones. The relationship between tone and vowel duration was generally similar to that of normals for all brain-damaged speakers. A comparison of aphasics' performance on tone perception (J. Gandour & R. Dardarananda, 1983, Brain and Language, 18, 94-114) and tone production indicated that, for the normal and right brain-damaged subjects, performance on the perception task was higher than on production, whereas the opposite was true for the aphasics. These data are brought to bear on issues related to tone production in aphasia, consonant and vowel production in aphasia, hemispheric specialization for tone production, intonation production in aphasia, relationship between speech perception and speech production, and tone production in dysarthria with cerebellar disease.     

The relation between gesture and language in aphasic communication

Effective communication in aphasia depends not only on use of preserved linguistic capacities but also (and perhaps primarily) on the capacity to exploit alternative modalities of communication, such as gesture. To ascertain the capacity of aphasic patients to use gesture in their spontaneous communication, informally structured interviews were conducted with two Wernicke's aphasics and two Broca's aphasics, as well as with four normal controls. The performances of the patient groups were compared on the physical parameters of gesture, the points in the communication where gestures occurred, and several facets of the semantics and pragmatics of gesture. Generally speaking, the gestures of the aphasics closely paralleled their speech output: on most indices, the performance of the Wernicke's aphasics more closely resembled that of the normal controls. Wernicke's aphasics differed from normals in the clarity of their language and gestures: While individual linguistic units were often clear, the relation among units was not. In contrast, the Broca's aphasics equaled or surpassed the normal controls in the clarity of their communications. The results offer little support for the view that aphasic patients spontaneously enhance their communicative efficacy through the use of gesture; these findings can, however, be interpreted as evidence in favor of a “central organizer” which controls critical features of communication, irrespective of the modality of expression.     

Sentence comprehension by Broca's aphasics: Effects of some suprasegmental variables

Three subtests of comprehension (one of varying sentential stress, one of shifting juncture, and one of applying emphatic stress to functors) were administered to eight Broca's aphasics and eight controls to determine the effects of stress and juncture on disambiguation of these sentences. Data indicated that the aphasic group performed significantly worse than the normals on all three subtests of comprehension. In addition, there was a strong positive correlation between severity of aphasia and error scores for all three tests. Results are discussed in relation to intact-vs.-disordered comprehension.     

PET activation studies comparing two speech tasks widely used in surgical mapping

"Automatic" speech, especially counting, is frequently preserved in aphasia, even when word production is severely impaired. Although brain sites and processes for automatic speech are not well understood, counting is frequently used to elicit fluent speech during preoperative and intraoperative cortical mapping for language. Obtaining both behavioral and functional brain imaging measures, this study compared counting with a word production task (generation of animal names), including non-verbal vocalizations and quiet rest as control states, in normal and aphasic subjects. Behavioral data indicated that normal and aphasic groups did not differ in counting or non-verbal vocalizations, but did differ significantly in word production ("naming" animals). Functional brain imaging results on normal subjects using partial least squares analysis of PET rCBF images revealed three significant latent variables (LVs): one for naming and vocalizing, identifying bilateral anterior areas, with left predominating over right; a second LV for naming, identifying left and right frontal and temporal areas. For the third, only marginally significant LV, which was associated with automatic speech alone (counting), right and subcortical sites predominated. For patients, two LVs emerged, identified with naming and vocalization, and corresponding to a variety of cerebral sites; the analysis failed to find a specific latent variable for counting. A comparison between group data for normal subjects and patients suggested that the naming, counting, and vocalization tasks were performed differently by the two groups. These results suggest that word generation as a verbal task is more likely to elicit activity in classical language areas than counting. Further studies are suggested to better understand differences between neurological substrates for non-propositional and automatic speech.     

An acoustic study of vowel production in aphasia

A group of five anterior and seven posterior aphasic patients were recorded for their vowel productions of the nine nondipthong vowels of American English and compared to a group of seven normal speakers. All phonemic substitutions were eliminated from the data base. A Linear Predictive Coding (LPC) computer program was used to extract the first and the second formant frequencies at the midpoint of the vowel for each of the remaining repetitions of the nine vowels. The vowel duration and the fundamental frequency of phonation were also measured. Although there were no significant differences in the formant frequency means across groups, there were significantly larger standard deviations for the aphasic groups compared to normals. Anterior aphasics were not significantly different from posterior aphasics with respect to this greater formant variability. There was a main effect for vowel duration means, but no individual group was significantly different from the other. Standard deviations of duration were significantly greater for the anterior aphasics compared to normal speakers, but not significantly different from posterior aphasics. Posterior aphasics did not have significantly greater standard deviations of duration than did normal subjects. Greater acoustic variability was considered to evidence a phonetic production deficit on the part of both groups of aphasic speakers, in the context of fairly well-preserved phonemic organization for vowels.     

Automatic and volitional semantic processing in aphasia.

The present study investigated the status of semantic information in aphasia by comparing the performances of aphasic and nonaphasic subjects on two tasks: an automatic semantic facilitation task and a volitional task of relatedness judgment. Both the aphasic and nonaphasic groups evidenced a semantic facilitation effect, in an on-line task of semantic processing. However, those aphasics with severe comprehension and naming disturbances (termed low comprehension aphasics) demonstrated considerable difficulty in judging the relatedness between a pictured object and members of that object's semantic field, the severity of the impairment being greater for those pictures that the low comprehension aphasics were unable to name. The pattern of results can best be explained by supposing the structural integrity of the store of semantic information in aphasia, and in particular in low comprehension aphasia: information that is retrieved and manipulated in judgment-mediated tasks with considerable difficulty.