Clinical-anatomical correlation in a selective phonemic speech production impairment

Although phonemic paraphasias are common in aphasic disorders, including Broca's aphasia, conduction aphasia and transcortical motor aphasia, selective phonemic speech production impairment, or phonemic disintegration, is unusual. A patient with a selective phonemic speech production disorder underwent clinical, neuropsychological and structural neuroradiological assessment over a period of 6 years. The disorder was characterised by phonemic paraphasias (phonemic disintegration) with preserved comprehension and naming. Imaging showed a focal lesion in the white matter of the left precentral gyrus and, to a lesser extent, the posterior part of the left middle frontal gyrus, with overlying cortical atrophy. Biopsy of the lesion, after several years of observation, showed a calcified haemangioma. Clinical-anatomical correlation in this case suggests the importance of primary motor cortex of the inferior precentral (pre-Rolandic) gyrus and subjacent white matter in phoneme production, with sparing of the posterior inferior frontal gyrus (Broca's area).     

The Relationship Between Type of Naming Error and Semantic-Lexical Discrimination in aphasic Patients

When submitted to confrontation naming tasks, aphasic patients show different types of naming errors: phonetic, phonemic and verbal-semantic paraphasias, neologisms and anomia, but it is generally difficult to decide whether these errors are mainly due to a breakdown of the semantic systems or to post-lexical phonological disorders. In order to clarify this issue, 118 aphasic patients were given 3 tests of confrontation naming and 3 tests of semantic-lexical discrimination. Naming errors on confrontation were used to classify aphasic patients in various subgroups (according to the prevalence of a given type of naming error), whereas performances obtained on tests of semantic-lexical discrimination were taken as an index of disorganization of the semantic systems. The performances on semantic discrimination tests of patients showing a prevalence of phonetic, phonemic and verbalsemantic paraphasias, neologisms and anomia on confrontation naming tasks were compared. a very small number of semantic discrimination errors was obtained by patients showing a prevalence of phonetic or phonemic transformations on confrontation, whereas a much larger number of semantic discrimination errors was obtained by patients showing a prevalence of verbal-semantic paraphasias, neologisms and anomia.     

Revealing and quantifying the impaired phonological analysis underpinning impaired comprehension in Wernicke's aphasia

Wernicke's aphasia is a condition which results in severely disrupted language comprehension following a lesion to the left temporo-parietal region. A phonological analysis deficit has traditionally been held to be at the root of the comprehension impairment in Wernicke's aphasia, a view consistent with current functional neuroimaging which finds areas in the superior temporal cortex responsive to phonological stimuli. However behavioural evidence to support the link between a phonological analysis deficit and auditory comprehension has not been yet shown. This study extends seminal work by Blumstein, Baker, and Goodglass (1977) to investigate the relationship between acoustic-phonological perception, measured through phonological discrimination, and auditory comprehension in a case series of Wernicke's aphasia participants. A novel adaptive phonological discrimination task was used to obtain reliable thresholds of the phonological perceptual distance required between nonwords before they could be discriminated. Wernicke's aphasia participants showed significantly elevated thresholds compared to age and hearing matched control participants. Acoustic-phonological thresholds correlated strongly with auditory comprehension abilities in Wernicke's aphasia. In contrast, nonverbal semantic skills showed no relationship with auditory comprehension. The results are evaluated in the context of recent neurobiological models of language and suggest that impaired acoustic-phonological perception underlies the comprehension impairment in Wernicke's aphasia and favour models of language which propose a leftward asymmetry in phonological analysis.     

"Transcortical" features of aphasia following left thalamic hemorrhage.

In a series of 14 thalamic hemorrhage documented by Computerized Axial Tomography (CT) scans, aphasia was present in seven out of eight patients with left lesions while it was absent in the six patients with right lesions. In three cases where detailed language testing was performed, aphasia was characterized by reduction of spontaneous speech with semantic paraphasias, preserved repetition and partially defective auditory verbal comprehension. The language disturbance was persistent in two patients, while it recovered spontaneously within four weeks in one patient. The clinical picture in these patients is similar to the classical "transcortical" aphasias, which are usually due to damage of the marginal language areas. It is suggested that the left thalamus contributes to the semantic level of verbal behavior, which is possibly subserved by these areas.     

The use of phonemic cueing with Alzheimer's disease patients

Variables influencing responsiveness to phonemic cueing, although studied extensively in the aphasia population, have not been identified in the Alzheimer's disease population. In this study, four variables were analyzed in relation to successfulness of phonemic cueing: severity of dementia, confrontational naming ability, auditory comprehension, and speech fluency. All three language measures showed a significant positive correlation with cueing. Severity of dementia showed a significant inverse correlation with responsiveness to cueing and was the best predictor of successful use of cueing. It was concluded that phonemic cueing aided in label retrieval, problematic in the early stages of Alzheimer's disease, prior to significant erosion of semantic meaning.     

Agraphia and preservation of music writing in a bilingual piano teacher

A bilingual virtuoso piano teacher developed aphasia and amusia, probably due to cerebral embolism. The perfectly demarcated and unique lesion was located in the left posterior temporoparietal region. Language examinations in French and Italian demonstrated entirely comparable difficulties in both languages. The linguistic course was favorable after a period of auditory agnosia and global aphasia. Language became fluent again 3 months after the onset, with a marked vocabulary loss and phonemic paraphasias with attempts at self-correction. Repetition was altered markedly with a deficit in auditory comprehension but no remaining elements of auditory agnosia. Reading was possible, but with some difficulty and total agraphia and acalculia persisted. Musical ability was better conserved, particularly with respect to repetition and above all to writing, the sparing of the latter constituting a fairly uncommon dissociation in relation to agraphia. Findings are discussed in relation to data in the literature concerning hemispheric participation in various musical tasks.     

失语患者听理解中的特殊范畴语义障碍

目的：探讨失语患者听理解中特殊范畴语义障碍的特点。方法：（1）用汉语失语检查法（ABC）检查42例卒中后失语患者，其中，Broca失语（BA）8例，Wernicke失语9WA）5例，传导性失语（CA）11例，经皮质运动性失语（TCM）8例，经皮质感觉性失语（TCS）7例，命名性失语（AA）3例；（2）分别统计各型失语患者ABC中听辨认9项的得分，并用SPSS软件处理数据。结果：（1）BA、TCM和AA患者听辨认9项间差异无显著性意义（P＞0．05）。（2）WA、CA、TCS患者对9个项目的听辨认存在不同程度困难；物品和动作听理解障碍的程度较轻，而颜色和（或）身体部位的听理解障碍较重。差异有显著意义的（P＜0．05）是：WA患者在物品（M＝4分）、物品图（M＝6分）、动作图（M＝4分）与颜色（M＝0）分、家具（M＝0分）及身体部位（高、低频和左／右）（M＝2，0，0分）间，几何图（M＝2分）与物品图及身体部位（低频）间；CA患者在物品（M＝10分）、物品图（M＝10分）、动作图（M＝10分）与身体部位（高、低频和左／右）（M＝9，8，4分）间，几何图（M＝9分）与物品图间，颜色（M＝10分）、家具（M＝10分）与身体部位（低频）间；TCS患者在物品（M＝10分）与家具（M＝5分）和身体部位（低频）（M＝6分）间，动作图（M＝10分）、家具和身体部位（低频）间。结论：（1）失语患者听理解中特殊范畴语义障碍主要见于有明显听理解障碍者，（2）不同型失语患者的听辨认中有相似的特殊范畴语义障碍。     

Computer-mediated tools for the investigation and rehabilitation of auditory and phonological processing in aphasia

Background : Advances in technology have enhanced our ability to use computers to manipulate the spectrotemporal characteristics of speech waveforms in ways that can influence the processing of linguistically important features. These modifications are important in patients with auditory/phonetic processing disorders. Aims : We present some preliminary data detailing the effect of modifying the spectrotemporal structure of speech on the ability to discriminate consonant-vowel syllables and comprehend spoken words and sentences in a case of Pure Word Deafness (PWD). Methods & Procedures : We documented severe phonemic processing deficits in a patient with PWD resulting from a unilateral left temporal lesion. Her ability to distinguish between stop consonants was severely impaired while her perception of vowels was relatively spared. This pattern suggested problems with online perceptual elaboration of short-term acoustic features such as rapid formant frequency transitions. We digitally synthesised consonant-vowels with normal (40 millisecond) and extended (80 millisecond) formant frequency transitions and examined her ability to discriminate these stimuli when presented in rapid sequence. In addition, we temporally expanded natural words and sentences by 1.5 and 2 times their original duration (without altering voice pitch) and examined the effects of these manipulations on her auditory comprehension. Outcomes & Results : Altering the temporal parameters of speech had varied effects on decoding auditory linguistic information. Temporal expansion of sentences produced a small but noteworthy increase in performance on an auditory language comprehension task. Extension of brief formant transitions had no substantial effect on phonemic discrimination of rapidly presented CV pairs. Conclusions : These findings illustrate that temporal conditioning of auditory stimuli can potentially enhance the ability of patients with PWD to comprehend speech. The implications of the findings for aphasia therapy are discussed.     

Distinguishing semantic and lexical word retrieval deficits in people with aphasia

Background: Identifying the point of breakdown in people with aphasia with disorders of word retrieval is not straightforward. Evidence has been sought from: (i) the nature of the errors in naming; (ii) the variables affecting naming accuracy; (iii) the effects of correct and misleading cues; (iv) performance in other word comprehension and production tasks. However, previous research has demonstrated that each of these sources of evidence provides information compatible with more than level of breakdown. Aims: The study investigates whether a combination of information from these sources can provide a coherent account of how word retrieval is breaking down in people with aphasia. Methods & Procedures: Three people with aphasia (JGr, LM, and KS) took part in four experiments. The first investigated the errors made in picture naming and the factors (target word length, imageability, frequency …) affecting naming accuracy. The second experiment investigated the effects of correct phonemic cues and miscues on word retrieval. The third examined the participants' performance in tests of spoken and written word and picture comprehension. The fourth experiment investigated whether the participants had the processing abilities necessary to generate their own phonemic cues in spoken naming from orthographic information. Outcomes & Results: Evidence from these investigations showed different levels of breakdown in the three participants. JGr's naming was characterised by semantic errors, effects of target imageability and familiarity on naming accuracy, improved naming with correct phonemic cues and semantic errors with miscues, and poor performance in word comprehension tasks. This pattern is consistent with a breakdown at a semantic level underlying JGr's difficulty in word retrieval. In contrast, LM shows performance indicating a breakdown in mapping between intact semantic and phonological representations. He makes primarily no response errors in naming and his accuracy is affected only by frequency and familiarity. Correct phonemic cues can improve his naming accuracy to near normal levels, and he makes no semantic errors, although he is slowed by miscues. His word and picture comprehension is intact. KS shows a more complex pattern of impairment. Like JGr, she shows evidence of a semantic impairment: she makes semantic errors in naming, and her accuracy is affected by target imageability. She makes errors in word comprehension and her word retrieval is adversely affected by miscues. There are two unusual features to her performance: her naming accuracy is not improved by initial phoneme cues (despite effects of miscues and more extensive phonemic cues), and she is better at naming pictures with longer names (a “reverse length effect”). Investigations in experiment four show that KS is using orthographic information on the initial letter of names to generate her own phonemic cues; it is concluded that in addition to her semantic deficit she has an impairment in access to lexical phonological representations. Conclusions: We conclude that careful investigation of the performance of people with aphasia across a range of tasks can be used to identify underlying levels of breakdown in word retrieval. However, superficial resemblances between people with aphasia can be misleading.     

Primary progressive non-fluent aphasia: a case study

A case study of a 65 year old man is described with an eight-year history of progressive primary non-fluent aphasia accompanied by agrammatism, phonemic paraphasias and mild spelling dysgraphia. His naming ability, however, has remained at an exceptionally high level and there has been no evidence of impairment of word or sentence comprehension. Non-verbal skills and memory functions have also been preserved within the range of his very high premorbid level of abilities. Single photon emission computed tomography was consistent with bifrontal hypoperfusion. We argue that the selective language deficits in this patient are characteristic of dynamic aphasia and of other speech disturbances which are also known to be associated with left frontal lesions. The possible underlying pathology is discussed in the context of known degenerative disorders.     

Control mechanisms of aphasic patients in verbal and phonemic paraphasias (author's transl)]

In the current literature on aphasia, two explanations of paraphasic errors are suggested: one is based on the idea of conscious verbal substitutions, and the other on that of uncontrolled faults in production. The purpose of this study was to relate both explanations to a) the usual classification of verbal and phonemic paraphasias, b) the different types of aphasia, and c) the severity of the aphasic disturbance. In free reproductions of 19 fluent aphasics A(F) and 21 nonfluent aphasics A(NF), the immediate verbal context of paraphasias was examined in relation to a) the nature and severity of the paraphasic errors and b) the severity of the aphasia. The A(NF) group made significantly more hesitations before both verbal and phenemic paraphasias. There was no significant difference between the two groups in control after phonemic paraphasias, but the A(NF) showed a significantly higher rate of control incidents after verbal paraphasias. Thus the two explanations of paraphasia may correspond to different kinds of paraphasic behavior, which are symptomatic of two varieties of aphasia, fluent and nonfluent.     

传导性失语复述障碍机制的研究进展

传导性失语以严重的复述障碍、听理解能力相对较好为特点,同时有语音错误及命名障碍。本文从传导性失语的病变部位及关于传导性失语复述障碍机制的经典理论:联系中断学说、中心性失语理论、短时记忆缺损模式及双向分布模式,阐述了传导性失语复述障碍机制的研究进展。     

Cortico-subcortical organization of language networks in the right hemisphere: an electrostimulation study in left-handers

We have studied the configuration of the cortico-subcortical language networks within the right hemisphere (RH) in nine left-handers, being operated on while awake for a cerebral glioma. Intraoperatively, language was mapped using cortico-subcortical electrostimulation, to avoid permanent deficit. In frontal regions, cortical stimulation elicited articulatory disorders (ventral premotor cortex), anomia (dorsal premotor cortex), speech arrest (pars opercularis), and semantic paraphasia (dorsolateral prefrontal cortex). Insular stimulation generated dysarthria, parietal stimulation phonemic paraphasias, and temporal stimulation semantic paraphasias. Subcortically, the superior longitudinal fasciculus (inducing phonological disturbances when stimulated), inferior occipito-frontal fasciculus (eliciting semantic disturbances during stimulation), subcallosal fasciculus (generating control disturbances when stimulated), and common final pathway (inducing articulatory disorders during stimulation) were identified. These cortical and subcortical structures were preserved, avoiding permanent aphasia, despite a transient immediate postoperative language worsening. Both intraoperative results and postsurgical transitory dysphasia support the major role of the RH in language in left-handers, and provide new insights into the anatomo-functional cortico-subcortical organization of the language networks in the RH-suggesting a “mirror” configuration in comparison to the left hemisphere.     

Inhibition and auditory comprehension in Wernicke's aphasia

Background: While research findings support the presence of inefficiencies in allocation of attention in individuals with aphasia, the cognitive mechanisms behind these inefficiencies remain unclear. One mechanism that would affect resource allocation for selective processing is an impaired inhibitory mechanism which, when normally functioning, would actively suppress distracting information. Aims: The purpose of this study was to investigate the cognitive process of inhibition, at the lexical‐semantic level of language processing, and its relation to auditory comprehension in Wernicke's aphasia. Methods & Procedures: The classic Stroop Colour‐Word Test was adapted to be applicable for use with an aphasic population. We administered this computerised manual‐response, numerical version of the Stroop test to five individuals with Wernicke's aphasia and twelve age‐ and education‐matched non‐brain‐injured controls. Correlations with Stroop interference examined associations with auditory comprehension as measured by the Token Test and the Complex Ideational Material subtest of the Boston Diagnostic Aphasia Examination. Outcomes & Results: Analysis of the Stroop reaction time and error percentage data indicated that the interference effect was significantly larger for the participants with Wernicke's aphasia than for the controls, without an accompanying increase in facilitation, reflecting an impairment of inhibition in Wernicke's aphasia. In addition, the magnitude of Stroop interference was significantly positively correlated with the clinical‐behavioural symptom of severity of auditory comprehension deficits as measured by the Token Test. Conclusions: Findings support an impairment in inhibition at the lexical‐semantic level of language processing in Wernicke's aphasia, reflecting the inability to effectively ignore the automatically evoked, distracting stimulus. The significant correlation between the Stroop interference effect and the severity of auditory comprehension deficits suggests that at least part of the attentional difficulties contributing to the striking reductions in auditory comprehension in this population can be attributed to impaired inhibition. Our findings expand upon our understanding of resource allocation in aphasia and reinforce our need to clinically assess and treat reductions in attention for maximised rehabilitation outcome.     

Naming concepts: evidence of two routes

This study examines a parallel distributed processing (PDP) model (partly based on the Wernicke-Lichtheim information processing model) that posits two routes for naming concepts, whole word and phonological. To test the two naming route hypothesis of this model, we performed confrontation naming tests that were either uncued, semantically cued, or phonologically cued in a patient with naming impairment due to Broca's aphasia. In spoken language and in uncued naming to confrontation, word retrieval was severely impaired and marked by semantic but no phonemic paraphasic errors. With semantic cues, naming behavior was unchanged; however, with phonological cues, naming success was enhanced but frequent phonemic paraphasias were produced. These results suggest that the patient spontaneously engaged the whole word naming route, but when given phonological cues, he engaged an alternative phonological naming route that incorporated phonological sequence knowledge.     

不同型失语症患者的复述障碍

目的 探讨不同型失语症患者的复述障碍特点。方法 设计8组近音单字词及词的图画,对不同型失语症患者做复述检查。结果 3例传导性失语症患者复述障碍最重,复述错误主要为音位性错语,但大多配画正确;3例经皮质感觉性失语症患者的复述错误中,9个音位性错语及2个词义性错语,大多错语配画正确,但16个复述正确的词配错画;7例经皮质运动性失语症患者中,5例复述和配画全对,另1例口语表达表现为语音障碍,1例在复述中有持续现象。结论 本文三型失语症患者复述障碍的特点不同,揭示其复述障碍各有不同的病理生理机制。     

Aphasia in multiple sclerosis.

In a 17-year-old woman, motor aphasia developed during her second bout of multiple sclerosis, characterized by absent spontaneous speech, paraphasias in naming and repetition, and marked orofacial apraxia, with relative preservation of written language and intact auditory comprehension. A mild right hemiparesis was associated. Bilateral cerebral lesions were demonstrated on a computerized tomographic brain scan. The aphasia remitted over 1 month.     

The Influence of refractoriness upon comprehension of non-verbal auditory stimuli

An investigation of non-verbal auditory comprehension in two patients with global aphasia following stroke is reported. The primary aim of the investigation was to establish whether refractory access disorders can affect non-verbal input modalities. All previous reports of refractoriness, a cognitive syndrome characterized by response inconsistency, sensitivity to temporal factors and insensitivity to item frequency, have involved comprehension tasks which have a verbal component. Two main experiments are described. The first consists of a novel sound-to-picture and sound-to-word matching task in which comprehension of environmental sounds is probed under conditions of semantic relatedness and semantic unrelatedness. In addition to the two stroke patients, the performance of a group of 10 control patients with non-vascular pathology is reported, along with evidence of semantic relatedness effects in sound comprehension. The second experiment examines environmental sound comprehension within a repetitive probing paradigm which affords assessment of the effects of semantic relatedness, response consistency and presentation rate. It is demonstrated that the two stroke patients show a significant increase in error rate across multiple probes of the same set of sound stimuli, indicating the presence of refractoriness within this non-verbal domain. The implications of the results are discussed with reference to our current understanding of the mechanisms of refractoriness.