Age and evolution of language area functions. A study on adult stroke patients

This study attempted to verify some of the hypotheses advanced to explain the repeatedly reported finding that non-fluent aphasics are younger than fluent aphasics. One hundred and ninety eight vascular patients with cerebral infarcts documented by CT-scan were investigated. Also in this sample fluent patients were older than non-fluent patients. Age was found not to differ according to lesion site (anterior versus posterior). Patients with extensive lesions were, on average, younger than those with more restricted damage. The most interesting finding was that more than half patients with anterior lesion had fluent aphasia and that were remarkably older than anterior patients presenting with the classical non-fluent picture. It is inferred that anterior language areas undergo some kind of progressive functional evolution with age, though not in the sense postulated by Brown and Jaffe.     

Broca aphasia with neologisms]

Patients with jargon aphasia generally have fluent speech with poor comprehension. However, outstanding jargons may appear in non-fluent aphasics. We report a 69-year-old left-handed woman with non-fluent jargon aphasia due to lesions in the right frontoparietal area. Features of her speech included non-fluent meaningless sequences of syllables, i. e., phonetic jargon, which was obvious in all the tasks including spontaneous speech, repetition, naming and reading. Her utterance was sparse, but not effortful or anarthric. She understood most of spoken single words, but was confused by complex sentences. Brain CTs revealed acute lesions affecting the inferior and middle frontal gyri, insular cortex, precentral and postcentral gyri, and a part of the angular gyrus in the right hemisphere. Old infarcts were also noted in the right frontal pole and prefrontal area. The unique feature of her language impairment suggested somewhat deviated lateralization and localization of her language function.     

Subcortical aphasia: two clinical-CT scan correlation studies

Two clinical-CT scan studies were undertaken in order to investigate the frequency and the characteristics of aphasia following strictly subcortical left hemisphere lesions. In Study 1, all patients whose CT scan, carried out within a given period, showed subcortical lesions in both hemispheres, were evaluated for presence and type of aphasia; conversely, in Study 2 the records of all patients referred to our Aphasia Unit for language evaluation within a given period, were examined for presence of subcortical lesions on the CT scan. In Study 1 aphasia was found in two out of six patients. In Study 2 stabilized, strictly subcortical lesions of the left hemisphere were found in six out of 250 patients referred to the Aphasia Unit; 4 out of 6 were aphasics. Closer scrutiny of the type of language disorder in the aphasics from both studies (N = 6) suggests the possibility of differentiating two types of defect: an atypical non fluent aphasia, sometimes associated with anterior capsular-putaminal lesions, and a mild fluent aphasia, sometimes associated with posterior capsular-putaminal lesions.     

The contribution of working memory to language comprehension: differential effect of aphasia type

Background: Experimental studies of short-term memory and working memory (WM) in aphasia fail to discriminate cognitive impairments of different aphasia types—non-fluent, Broca-type aphasia and fluent, Wernicke-type aphasia. However, based on the varying fundamental features of these two aphasia syndromes, the potentially different underlying mechanisms of impairment and scant preliminary evidence of varying cognitive deficits, a differential relationship between cognitive function and language processing in these two groups can be predicted.

Aims: The current study investigates the hypothesis concerning the differential impact of cognitive impairments in individuals with fluent versus non-fluent aphasia types.

Methods & Procedures: Participants with fluent (n = 19) and non-fluent (n = 16) aphasia and participants without brain damage (n = 36) were presented with an eye-tracking WM task. Additionally, individuals with aphasia completed two language comprehension tasks.

Outcomes & Results: Results revealed significant decrease in WM capacity in individuals with aphasia compared with participants without brain damage. The two aphasia groups performed similarly on the WM and language tasks. Furthermore, for participants with non-fluent aphasia, it was revealed that WM makes a significant contribution to language comprehension, while for fluent individuals this relationship was not significant.

Conclusions: Overall, the present data support the claim that there are cognitive deficits in aphasia and that these cognitive deficits tend to exacerbate the language impairments of persons with non-fluent aphasia types. The results are discussed in the context of varying mechanisms of impairment in different types of aphasia. The present findings have important implications both for the assessment and the treatment of individuals with aphasia and for understanding the nature of aphasia.     

Localization of aphasic symptoms: preliminary observations with C.T. scanner (author's transl)

Twenty patients with aphasia and left-hemisphere damage were examined with a standard language battery, and Computerized Axial Tomography. Patients were divided into fluent (N = 9) and nonfluent (N = 6) on the basis of the language examination; 5 patients who could not be classified in either category were excluded. Lesions were retrorolandic in 8 out of 9 fluent aphasics while extending anteriorly in all 6 nonfluent aphasics. Some unexpected lesions were also found. Five cases -- 3 fluent and 2 nonfluent -- are discussed in detail.     

Verbal coding and visual memory in aphasics

Fluent and non-fluent aphasics, non-aphasic brain-damaged patients, schizophrenics, and normal controls were tested in a non-verbal visual retention task (object-drawings, snowflakes). All groups of neurological and psychiatric patients scored lower than normal controls under a rehearsal condition. Differences levelled off when a distractor task was interpolated. While fluent aphasics were impaired with both the object-drawings and the snowflakes, non-fluent aphasics were impaired only with the latter. Results are discussed with respect to the verbal-encoding hypothesis and other theories of aphasia.     

The relationships between conceptual and semantic-lexical disorders in aphasia

A nonverbal test of conceptual thinking was administered to 55 normal controls and to 203 patients with monohemispheric brain lesions (74 aphasics and 129 nonaphasic brain-damaged patients), in order to study the relationships between conceptual impairment of aphasic patients and breakdown of the semantic-lexical level of integration of language. A very high number of aphasic patients (54 out of 74) and a limited number of nonaphasic brain-damaged subjects (31 out of 129) obtained a pathological score on the test of conceptual thinking, but only some components of the aphasic symptomatology seemed closely linked to the conceptual disorder. In fact a non-significant relationship was found between conceptual impairment and: ("fluent" or "non-fluent") clinical type of aphasia; severity of aphasic disturbance. On the contrary, a strong relationship was found between conceptual disorder and impairment of the semantic-lexical level of integration of language. These findings seem to show that conceptual disturbance and semantic-lexical troubles are closely linked in aphasia.     

Role of cognitive control in language deficits in different types of aphasia

ABSTRACT

Background: Although studies show that different facets of cognitive control are impaired in persons with aphasia (PWA), the question how they impact language abilities in different types of aphasia remains open.

Aims: Following the hypothesis that diminished attention contributes to language impairments in aphasia, we predicted that both fluent and non-fluent PWA would perform worse than neurologically intact individuals on verbal and non-verbal cognitive control tasks. Also, testing the view that linguistic disturbances in fluent and non-fluent PWA dissociate, we predicted differential relationships in performance on cognitive control tasks and language impairment.

Methods & Procedures: Fluent PWA (N = 17) and non-fluent PWA (N = 14) were compared to unimpaired speakers (N = 21) on the non-verbal Flanker task tapping domain-general cognitive control, and Stroop task measuring verbal cognitive control, as well as subtests from the Russian version of the Birmingham Cognitive Screen, namely the Auditory Control task tapping verbal cognitive control and the Rule Finding task measuring domain-general cognitive control. All PWA completed picture naming and language comprehension tasks.

Outcomes & Results: All PWA were more impaired on the Stroop and Auditory Control tasks, with no impairment on the non-verbal Flanker task compared to the controls. Non-fluent PWA also performed significantly worse on the Rule Finding that requires forming and updating non-verbal relational representations. Differences between aphasia groups were found on the Auditory Control task only, where non-fluent PWA were more vulnerable to task demands. Correlation analyses found that verbal and non-verbal cognitive control performance was correlated for the non-fluent group, whereas only correlations between verbal cognitive control tasks were significant for the fluent group. For all PWA, non-verbal cognitive control indexed by Flanker interference scores was related to language comprehension, whereas verbal cognitive control was related to picture naming. However, non-verbal relational reasoning as indexed by the Rule Finding task was significantly related to language comprehension in the non-fluent group only.

Conclusions: All PWA had diminished verbal cognitive control. Non-fluent PWA demonstrated higher vulnerability to domain-general cognitive control deficits compared to fluent PWA. Performance on verbal and non-verbal cognitive control tasks significantly overlapped in the non-fluent group only. Both groups recruited non-verbal cognitive control during language comprehension and verbal cognitive control during picture naming. Only non-fluent PWA relied on domain-general relational reasoning during language comprehension. These findings reinforce the importance of cognitive assessment in aphasia.     

Impairment of language is related to left parieto-temporal glucose metabolism in aphasic stroke patients

Summary Twenty-six aphasic patients who had an ischaemic infarct in the territory of the left middle cerebral artery (MCA) were investigated. Cranial computed tomography (CT) showed various lesion sites: infarcts restricted to cortical structures in 12 patients, combined cortical and subcortical infarcts in 7 and isolated subcortical infarcts sparing the left cortex in another 7 cases. ¹⁸F-2-fluoro-2-deoxyglucose positron emission tomography revealed remote hypometabolism of the left convexity cortex and of the left basal ganglia, which was extended further than the morphological infarct zone in all cases. Types and degrees of aphasia were classified using the Aachener Aphasie Test (AAT): 10 patients had global aphasia, 2 Broca's, 5 Wernicke's, and 5 amnesic aphasia. Four patients suffered from minimal or residual aphasic symptoms. The AAT results were compared with the regional cerebral metabolic rates of glucose of the left hemisphere. Irrespective of the infarct location all five AAT subtests (Token test, repetition, written language, confrontation naming, auditory and reading comprehension) were closely correlated among each other and with left parieto-temporal metabolic rates, whereas left frontal and left basal ganglia metabolism showed no significant correlation. The close relation between left temporo-parietal functional activity and all five AAT subtests suggests that the different aspects of aphasia tested by AAT can be related to a common disorder of language processing in those areas.     

Hemispheric alpha asymmetries of aphasic and normal subjects: Results from recognition and recall tasks using visually presented words of high and low imagery

Abstract

Hemispheric alpha asymmetries of normal males, normal females, and male aphasics were observed from anterior and posterior placement sites for recall and recognition of visually presented high and low imagery words, and during resting conditions. No significant differences were observed during the resting conditions between groups. However, during visual presentation of words the aphasics demonstrated significantly less alpha in the right hemisphere, while no differences were observed for the normal subjects. Both fluent and non-fluent aphasics demonstrated right hemisphere alpha suppression across stimulus and task conditions. The non-fluent aphasics demonstrated lower overall alpha power levels across hemispheres than did the fluent aphasics. Results are discussed relative to the aphasics becoming more dependent upon the processing resources of the intact right hemisphere during the course of language recovery.     

Dynamic-intentional thalamic aphasia: a failure of lexical-semantic self-activation

Background: Previous research has described patients with aphasia from thalamic lesions, some of whom were non-fluent with intact comprehension, others who were fluent with impaired comprehension, and some of whom are non-fluent with impaired comprehension. Whereas these three subtypes usually have normal repetition, they had impaired naming, suggesting a deficit in lexical (phonological word forms)-semantic processing. We report a patient with a left thalamic hemorrhage in which lexical-semantic representations appear to be intact but the patient demonstrates an inability to spontaneously activate his lexical-semantic system Methods: A 82-year-old, right-handed man presented with decreased verbal fluency and memory loss following a thalamic hemorrhage. Neuropsychological assessment revealed significant decrements in verbal fluency with intact naming, comprehension, repetition and vocabulary. Conclusions: To the best of our knowledge this pattern of language disturbance, which mirrors dynamic aphasia induced by frontal lesions, has not previously been described with thalamic injury. The thalamus has strong connections with the frontal lobe and rather than degradation of lexical-semantic representations, this patient's thalamic lesion probably induced frontal lobe dysfunction with a failure to spontaneously active lexical semantic representations.     

Spontaneous evolution of aphasia after ischaemic stroke

Abstract

The relatively few studies concerning spontaneous recovery from aphasia yield contradictory findings because of the large number of influencing factors. We have assessed a selected sample of 45 patients, none of whom received language therapy, in order to determine such patients' chances of spontaneous recovery in relation to type and severity of aphasia and size of lesion. Our results show comprehension to have the best recovery, independent of type and severity of aphasia. Expression shows a lower recovery, especially for non-fluent aphasics; their performance is also negatively influenced by oral apraxia. In addition, the overall severity of aphasia, associated with large lesions, is a negative prognostic factor for recovery of expression.     

Neural correlates of phonological and semantic-based anomia treatment in aphasia

Most naming treatments in aphasia either assume a phonological or semantic emphasis or a combination thereof. However, it is unclear whether semantic or phonological treatments recruit the same or different cortical areas in chronic aphasia. Employing three persons with aphasia, two of whom were non-fluent, the present study compared changes in neural recruitment associated with phonologic and semantic-based naming treatments. The participants with non-fluent aphasia were able to name more items following both treatment approaches. Although this was not the case for the participant who had fluent aphasia, her naming errors decreased considerably following treatment. Post-treatment fMRI revealed similar changes in neural activity bilaterally in the precuneus among the two non-fluent participants--increased activity was noted in the right entorhinal cortex and posterior thalamus on post-treatment scans for the third participant. These findings imply that cortical areas not traditionally related to language processing may support anomia recovery in some patients with chronic aphasia.     

Auditory micropattern discrimination in brain damaged subjects

Patients with cerebral lesions were given two tests of pitch discrimination. The first was a pure tone discrimination test; in the second, complex tones were employed in which the pitch difference between the test tones was a consequence of the temporal microstructure of the stimuli. In contrast to non-fluent aphasics whose performance was normal for both tests, six of the seven patients having a fluent aphasia performed normally on the first test but revealed a significant deficit in the second. Patients with right temporal lesions also had the same pattern of deficit. The results suggest that the temporal lobes play a special role in the processing of auditory information in which the temporal structure of the stimuli is a critical feature.     

Conversational dynamics between aphasics

Abstract

The aim of this study was to determine how aphasic patients take part in conversations, the manner in which their conversations proceed, and how they compensate for their disabilities in maintaining conversational flow. The aphasia group studied contained five aphasics with different symptoms. Four conversations (54 minutes) were videotaped through a one-way mirror and subsequently transcribed. The analysis was based on a seven-category system (moves) and conversational flow was described in terms of active and reactive utterances. The results showed that, using the number of moves and total speech time as criteria, individual speakers varied greatly in their degree of participation in discussions and had different interactive profiles. The speakers were divided into two groups according to the type and severity of aphasia. It was discovered that the groups did not differ in conversational behaviour in terms of active and reactive moves, but the non-fluent speakers differed from the fluent aphasics in their use of deviant conversational moves. There was therefore no clear relation between the type and severity of aphasia and participation in discussions. Implications for aphasia therapy are discussed.     

The effects of instrumentality and name relation on action naming in Russian speakers with aphasia

Background: A verb’s instrumentality and name relation to an associated instrument noun are among the factors influencing verb retrieval in speakers with aphasia. Previous data on the effects of these factors are equivocal, possibly due to language- and task-specific factors.

Aims: The present study aimed to investigate the nature of the instrumentality and verb-noun name relation effects by retesting them in a large sample of Russian-speaking individuals with fluent and non-fluent aphasia.

Methods & Procedures: Forty Russian-speaking individuals with aphasia (twenty with fluent and twenty with non-fluent aphasia) and twenty controls performed an action naming task. Overall accuracy scores and qualitative error types were analysed.

Outcomes & Results: A positive effect of instrumentality was found in both groups of individuals with aphasia. A negative effect of verb-noun name relation was found in non-fluent aphasia and was larger for verbs with a smaller overlap with the instrument noun. In both aphasia groups, semantically related errors were more numerous for non-instrumental than instrumental verbs, whereas phonological errors were more numerous for name-related than non-name-related instrumental verbs.

Conclusions: The positive effect of instrumentality on verb retrieval may be attributed to a facilitatory effect of richer conceptual representations of instrumental verbs. The negative effect of name relation on verb retrieval may be explained by interference of the phonological form of the instrument noun. These factors influence verb retrieval in aphasia and should be taken into account when developing testing/treatment materials and stimuli for experimental studies.     

Primary progressive dynamic aphasia and Parkinsonism: Generation,selection and sequencing deficits

MC is the first reported case of dynamic aphasia in the context of non-fluent progressive aphasia and Parkinson's disease. MC's language profile was characterised by the hallmark propositional language impairment despite well-preserved naming, reading, repetition and comprehension skills. The severity of MC's propositional language deficit was comparable to other dynamic aphasic patients. Word and sentence generation performance was severely impaired only when many competing responses were activated by a stimulus. Thus, when a dominant response was available verbal generation was satisfactory. MC also presented with a deficit in idea generation and fluent sequencing of novel thoughts as discourse generation was extremely reduced and perseverative. In addition, non-verbal generation was impaired although dissociations emerged. MC was able to generate novel designs and gestures but his performance was highly perseverative, and his motor movement selection was abnormal, resembling a non-random pattern. MC is the first dynamic aphasic case with concurrent deficits in three mechanisms thought crucial for conceptual preparation processes; namely impaired selection, impaired generation of ideas and impaired fluent sequencing of novel thoughts. The findings are discussed in relation to conceptual preparation processes and their organisation, accounts of dynamic aphasia and the roles of the left inferior frontal and basal ganglia regions in conceptual preparation processes for verbal and non-verbal generation.     

A comparison of two working memory tasks in aphasia

Background: Overall, there is growing consensus that working memory (WM) should be routinely assessed in individuals with aphasia as it can contribute significantly to their level of language impairment and be an important factor in treatment planning. However, there is still no consensus in the field as to which tasks should be used to assess WM in aphasia. The two main alternatives are adapted complex span tasks and N-back tasks. Both have been used interchangeably in previous studies of WM in aphasia, even though the correspondence between the two tasks has not been properly established.

Aims: The current study investigates the relationship between two WM tasks—complex span and N-back tasks—in a large sample of individuals with aphasia. The relationships of these tasks to measures of language comprehension are also explored, as well as differences in performance patterns between individuals with non-fluent and fluent aphasia.

Methods & Resources: Forty-four participants with aphasia (non-fluent: n = 27; fluent: n = 13; mixed: n = 4) were examined with a modified listening span task (Ivanova & Hallowell, 2014), an auditory verbal 2-back task, and a standardised Russian language comprehension test.

Outcomes & Results: Results revealed a moderate relationship between the two WM measures, but demonstrated a divergence in terms of their relationship to language comprehension. Performance on the modified listening span task was related to language comprehension abilities, but performance on the 2-back task was not, suggesting that the two tasks primarily index different underlying cognitive mechanisms. Furthermore, the relationship between the modified listening span task and language comprehension was significant for individuals with non-fluent aphasia, but not for those with fluent aphasia.

Conclusions: Overall, the data demonstrate that while performance of individuals with aphasia was related on the two tasks, the two tasks cannot be substituted for one another without further inquiries into their underlying differences.