AGR - 1 A Case Study of Cognitive Reserve and Wernicke's Aphasia Status-Post Insular Stroke

OBJECTIVE

The case is an 88-year-old, woman, formerly a successful surgeon for decades, with Wernicke's aphasia due to dominant insular stroke. Our evaluation explored her deficits in the context of the heterogeneous presentations of insular strokes and how speech rehabilitation has impacted her language abilities given her cognitive reserve prior to her stroke.

METHOD

The patient sustained a left MCA embolic stroke in 2020. Neurodiagnostics revealed an infarct in the insula, dominant temporal, frontal, and parietal lobes. Baseline language assessment was completed. Results included moderate-severe receptive language impairment; intact fluency; deficits in writing and repetition; and significant paraphasias.

RESULTS

Neuropsychological assessment demonstrated prominent deficits in repetition with paraphasias and irritability. Auditory learning, attention, and working memory were invalid due to deficits in repetition. She was diagnosed with mild vascular neurocognitive disorder and conduction aphasia.

CONCLUSIONS

Despite comprehension having improved, the patient's paraphasias resemble the presentation of Wernicke's aphasia. Interestingly, there were some consistencies in paraphasic errors, such as consistently swapping certain words or letters, demonstrating diminished but not absent volition of speech. Story memory was the most effective measure of auditory memory given repetition deficits. Despite repetition deficits commonly localizing to the supramarginal gyrus, her repetition difficulty is likely related to language network disruption due to her insular infarct. Rehabilitation for comprehension was successful despite age at time of injury. Consistent with previous research, results suggest despite cognitive reserve, repetition is resistant to rehabilitation; however, in this case, paraphasic errors were also resistant. Rehabilitation should include a behavioral component for insular stroke patients.

Inflectional Morphology in Fluent Aphasia: A Case Study in a Highly Inflected Language

Inflectional morphology difficulties are typically reported in non-fluent aphasia with agrammatism, but a growing number of studies show that they can also be present in fluent aphasia. In agrammatism, morphological difficulties are conceived as the consequence of impaired phonological encoding and would affect regular verbs more than irregular verbs. However, studies show that inflectional morphology difficulties concern both regular and irregular verbs, and that their origin could be more conceptual/semantic in nature. Additionally, studies report more pronounced impairments for the processing of the past tense compared to other tenses. The goal of this study was to characterize the impairment of inflectional morphology in fluent aphasia. RY, a 69-year-old man with chronic fluent aphasia completed a short neuropsychological and language battery and three experimental tasks of inflectional morphology. The tasks assessed the capacity to select the correct inflected form of a verb based on time information, to access the time information included in an inflectional morpheme, and to produce verbs with tense inflection. His performance was compared to a group of five adults without language impairments. Results showed that RY had difficulties selecting the correct inflected form of a verb, accessing time information transmitted by inflectional morphemes, and producing inflected verbs. His difficulties affected both regular and irregular verbs, and verbs in the present, past, and future tenses. The performance also shows the influence of processing limitations over the production and comprehension of inflectional morphology. More studies of inflectional morphology in fluent aphasia are needed to understand the origin of difficulties.

Deciphering the mechanisms of phonological therapy in jargon aphasia

BACKGROUND

Severe word production difficulties remain one of the most challenging clinical symptoms to treat in individuals with jargon aphasia. Clinically, it is important to determine why some individuals with jargon aphasia improve following therapy when others do not. We report a therapy study with AM, an individual with severe neologistic jargon aphasia, and provide a subsequent comparison with previous cases, with the purpose of informing both our theoretical and clinical understanding of jargon aphasia.

AIMS

To investigate AM's locus of word production deficit and determine the effectiveness of phonological component analysis (PCA) therapy, a phonological cueing therapy, in the re-learning and generalization of naming responses for words. In addition, AM's performance in therapy, linguistic profile and ability to engage with therapy/cues were compared in a retrospective analysis with the background linguistic and therapy data of two other individuals with jargon aphasia (P9 and FF), who responded differentially to PCA. This was undertake to explore possible prognostic indicators of phonological therapy for jargon aphasia.

METHODS & PROCEDURES

A battery of linguistic and neuropsychological tests was used to identify AM's word production deficit. A single-subject multiple probe design across behaviours was employed to evaluate the effects of PCA therapy on the re-learning and generalization of naming responses. In the retrospective analysis of AM, P9 and FF, we compared differences and similarities in performance on various linguistic tasks, the ability to engage in therapy (i.e., ability to generate and use the cues), as well as to retain and maintain cues.

OUTCOMES & RESULTS

AM's locus of deficit was identified in the mapping between semantics and phonology. PCA was found to be effective in improving naming in two of the three treated word lists during the treatment phase; however, these gains were not maintained. Generalization to untreated picture names was not observed. Findings from the retrospective analysis illustrated that oral reading skills, the ability to segment phonological information from words and active engagement with provided cues are likely prerequisites for obtaining robust and long-term gains.

CONCLUSIONS & IMPLICATIONS

We demonstrated that phonological therapy could be beneficial for the remediation of naming abilities at least in the re-learning phase; however, maintenance and generalization of these gains were limited. This research helps to elucidate the considerations and evaluations necessary for the appropriateness of phonological therapy and candidacy of individuals with jargon aphasia for this treatment approach.

The Relationship Between Confrontation Naming and Story Gist Production in Aphasia

PURPOSE

The purpose of this study was to examine the relationship between picture naming performance and the ability to communicate the gist, or essential elements, of a story. We also sought to determine if this relationship varied according to Western Aphasia Battery-Revised (WAB-R; Kertesz, 2007) aphasia subtype.

METHOD

Demographic information, test scores, and transcripts of 258 individuals with aphasia completing 3 narrative tasks were retrieved from the AphasiaBank database. Narratives were subjected to a main concept analysis to determine gist production. A correlation analysis was used to investigate the relationship between naming scores and main concept production for the whole group of persons with aphasia and for WAB-R subtypes separately.

RESULTS

We found strong correlations between naming test scores and narrative gist production for the large sample of persons with aphasia. However, the strength of the correlations varied by WAB-R subtype.

CONCLUSIONS

Picture naming may accurately predict gist production for individuals with Broca's and Wernicke's aphasia, but not for other WAB-R subtypes. Given the current reprioritization of outcome measurement, picture naming may not be an appropriate surrogate measure for functional communication for all persons with aphasia.

SUPPLEMENTAL MATERIALS

https://doi.org/10.23641/asha.5851848.

Exploring Treatment Fidelity in Persons With Aphasia Autonomously Practicing With Computerized Therapy Materials

PURPOSE

Current computer technologies permit independent practice for people with cognitive-communicative disorders. Previous research has investigated compliance rates and outcome changes but not treatment fidelity per se during practice. Our aim was to examine adherence to procedures (treatment fidelity) and accuracy while persons with aphasia independently practiced word production using interactive, multimodal, user-controlled, word-level icons on computers.

METHOD

Four persons with aphasia independently practiced single-word production after stimulation via user-initiated interactions in 3 conditions: (I) auditory stimulus with static representational drawing; (II) auditory stimulus with synchronized articulation video; and (III) users' choice between the 2 prior conditions. Sessions were video-recorded for subsequent analysis, which established emergently refined behavioral taxonomies using an iterative, mixed-methods approach.

RESULTS

In independent practice, users only sometimes adhere to modeled behaviors, other times improvising novel behaviors. The latter sometimes co-occurred with successful productions. Differences in success rates were noted between Conditions I and II across behaviors with Condition II generally favored. In Condition III, participants tended to choose the stimulus that resulted in highest success rates.

CONCLUSIONS

During independent practice with technology, persons with aphasia do not necessarily comply with clinicians' practice instructions, and treatment fidelity does not determine success. Autonomy and choice in practice may reveal unanticipated dimensions for computerized aphasia treatment.

Semantic fluency in aphasia: clustering and switching in the course of 1 minute

BACKGROUND

Verbal fluency tasks are included in a broad range of aphasia assessments. It is well documented that people with aphasia (PWA) produce fewer items in these tasks. Successful performance on verbal fluency relies on the integrity of both linguistic and executive control abilities. It remains unclear if limited output in aphasia is solely due to their lexical retrieval difficulties or has a basis in their executive control abilities. Analysis techniques, such as temporal characteristics of word retrieved, clustering and switching, are better positioned to inform the debate surrounding the lexical and/or executive control contribution for success in verbal fluency.

AIMS

To investigate the differences in quantitative (i.e., number of correct words) and qualitative (i.e., switching, clustering and word-retrieval times) performances on animal fluency task as a function of time between PWA and healthy control speakers (CS).

METHODS & PROCEDURES

Animal fluency data for 60 s were collected from 34 PWA and 34 CS, and responses were time stamped. The 60-s period was divided into four equal intervals of 15 s each (i.e., 15, 30, 45 and 60 s). The number of correct words, cluster size, number of switches, within-cluster pause and between-cluster pause were evaluated as a function of four 15-s time intervals between PWA and CS.

OUTCOMES & RESULTS

Compared with CS, PWA produced fewer words, had smaller cluster sizes and switched a fewer number of times. A decrease in the number of switches correlated with an increase in between-cluster pause durations. PWA showed longer within- and between-cluster pauses than CS. The two groups showed specific differences in the temporal pattern of the responses: as time evolved both PWA and CS showed decreased productivity for the number of correct words, but PWA reached the asymptote earlier in the time course than CS, neither group showed a change in cluster size, and the number of switches decreased as a function of time only for CS.

CONCLUSIONS & IMPLICATIONS

The findings suggest that for PWA the search and retrieval process is less productive and more effortful. This is indicated by smaller cluster size, fewer switches associated with increased between-cluster pause durations, as well as overall slowed retrieval times for the words. This shows that the difficulties with verbal fluency performance in aphasia have a strong basis in their lexical retrieval processes, as well as some difficulties in the executive component of the task.

Constraint-induced aphasia therapy versus intensive semantic treatment in fluent aphasia

OBJECTIVE

The authors compared the effectiveness of 2 intensive therapy methods: Constraint-Induced Aphasia Therapy (CIAT; Pulvermüller et al., 2001) and semantic therapy (BOX; Visch-Brink & Bajema, 2001).

METHOD

Nine patients with chronic fluent aphasia participated in a therapy program to establish behavioral treatment outcomes. Participants were randomly assigned to one of two groups (CIAT or BOX).

RESULTS

Intensive therapy significantly improved verbal communication. However, BOX treatment showed a more pronounced improvement on two communication-namely, a standardized assessment for verbal communication, the Amsterdam Nijmegen Everyday Language Test (Blomert, Koster, & Kean, 1995), and a subjective rating scale, the Communicative Effectiveness Index (Lomas et al., 1989). All participants significantly improved on one (or more) subtests of the Aachen Aphasia Test (Graetz, de Bleser, & Willmes, 1992), an impairment-focused assessment. There was a treatment-specific effect. BOX treatment had a significant effect on language comprehension and semantics, whereas CIAT treatment affected language production and phonology.

CONCLUSION

The findings indicate that in patients with fluent aphasia, (a) intensive treatment has a significant effect on language and verbal communication, (b) intensive therapy results in selective treatment effects, and (c) an intensive semantic treatment shows a more striking mean improvement on verbal communication in comparison with communication-based CIAT treatment.

Should pantomime and gesticulation be assessed separately for their comprehensibility in aphasia? A case study

BACKGROUND

Gesticulation (gestures accompanying speech) and pantomime (gestures in the absence of speech) can each be comprehensible. Little is known about the differences between these two gesture modes in people with aphasia.

AIMS

To discover whether there are differences in the communicative use of gesticulation and pantomime in QH, a person with severe fluent aphasia.

METHODS & PROCEDURES

QH performed two tasks: naming objects and retelling a story. He did this once in a verbal condition (enabling gesticulation) and once in a pantomime condition. For both conditions, the comprehensibility of gestures was analysed in a forced-choice task by naïve judges. Secondly, a comparison was made between QH and healthy controls for the representation techniques used.

OUTCOMES & RESULTS

Pantomimes produced by QH for naming objects were significantly more comprehensible than chance, whereas his gesticulation was not. For retelling a story the opposite pattern was found. When naming objects QH gesticulated much more than did healthy controls. His pantomimes for this task were simpler than those used by the control group. For retelling a story no differences were found.

CONCLUSIONS & IMPLICATIONS

Although QH did not make full use of each gesture modes' potential, both did contribute to QH's comprehensibility. Crucially, the benefits of each mode differed across tasks. This implies that both gesture modes should be taken into account separately in models of speech and gesture production and in clinical practice for different communicative settings.

Compound nouns in spoken language production by speakers with aphasia compared to neurologically healthy speakers: an exploratory study

Compounds are words that are made up of at least two other words (lexemes), featuring lexical and syntactic characteristics and thus particularly interesting for the study of language processing. Most studies of compounds and language processing have been based on data from experimental single word production and comprehension tasks. To enhance the ecological validity of morphological processing research, data from other contexts, such as discourse production, need to be considered. This study investigates the production of nominal compounds in semi-spontaneous spoken texts by a group of speakers with fluent types of aphasia compared to a group of neurologically healthy speakers. The speakers with aphasia produce significantly fewer nominal compound types in their texts than the non-aphasic speakers, and the compounds they produce exhibit fewer different types of semantic relations than the compounds produced by the non-aphasic speakers. The results are discussed in relation to theories of language processing.

Analysis of speech fluency in Williams syndrome

Williams syndrome (WS) is a neurodevelopmental genetic disorder, often referred as being characterized by dissociation between verbal and non-verbal abilities, although the number of studies disputing this proposal is emerging. Indeed, although they have been traditionally reported as displaying increased speech fluency, this topic has not been fully addressed in research. In previous studies carried out with a small group of individuals with WS, we reported speech breakdowns during conversational and autobiographical narratives suggestive of language difficulties. In the current study, we characterized the speech fluency profile using an ecologically based measure--a narrative task (story generation) was collected from a group of individuals with WS (n = 30) and typically developing group (n = 39) matched in mental age. Oral narratives were elicited using a picture stimulus--the cookie theft picture from Boston Diagnosis Aphasia Test. All narratives were analyzed according to typology and frequency of fluency breakdowns (non-stuttered and stuttered disfluencies). Oral narratives in WS group differed from typically developing group, mainly due to a significant increase in the frequency of disfluencies, particularly in terms of hesitations, repetitions and pauses. This is the first evidence of disfluencies in WS using an ecologically based task (oral narrative task), suggesting that these speech disfluencies may represent a significant marker of language problems in WS.

Semantic fluency and executive functions as candidate endophenotypes for the early diagnosis of schizophrenia in Han Chinese

Neurocognitive deficits are recognized as core features of schizophrenia. The aim of this study was to compare the cognitive performance of antipsychotic, drug-naive patients with first-episode schizophrenia (FES patients) to their healthy siblings and to healthy controls from the Han Chinese population for exploring potential endophenotypes for the early detection of schizophrenia. A battery of cognitive assessment tools was used to measure seven cognitive domains in matched groups consisting of 56 subjects each. Cognitive tests included the grooved pegboard test (GPT), the category fluency test (CFT), the trail making test A (TMT-A), the Wechsler memory scale-III spatial span test (WMS-III SST), the Hopkins verbal learning test-revised (HVLT-R), the brief visuospatial memory test-revised (BVMT-R), the paced auditory serial addition test (PASAT), and the Wisconsin card sorting test-64 cards version (WCST-64). The performances of FEP patients were inferior to normal controls on all neuropsychological tests, while siblings were lower than healthy controls in many of the same tasks. Patients' performances were lower than siblings' on all tests except for the CFT, the WMS-III SST backward test, and four subtests of the WCST-64. Our data suggest that FEP patients exhibited pronounced impairment of fine motor skills, speed of processing, attention, verbal memory, visual memory, and executive function, while siblings exhibited deficits intermediate between those of schizophrenic patients and the control group. Semantic fluency function and executive function may be potential endophenotypes for the early diagnosis of schizophrenia.

Therapy for naming difficulties in bilingual aphasia: which language benefits?

BACKGROUND

The majority of the world's population is bilingual. Yet, therapy studies involving bilingual people with aphasia are rare and have produced conflicting results. One recent study suggested that therapy can assist word retrieval in bilingual aphasia, with effects generalizing to related words in the untreated language. However, this cross-linguistic generalisation only occurred into the person's stronger language (L1). While indicative, these findings were derived from just three participants, and only one received therapy in both languages.

AIMS

This study addressed the following questions. Do bilingual people with aphasia respond to naming therapy techniques developed for the monolingual population? Do languages respond differently to therapy and, if so, are gains influenced by language dominance? Does cross-linguistic generalisation occur and does this depend on the therapy approach? Is cross-linguistic generalisation more likely following treatment in L2 or L1?

METHODS & PROCEDURES

The study involved five aphasic participants who were bilingual in English and Bengali. Testing showed that their severity and dominance patterns varied, so the study adopted a case series rather than a group design. Each person received two phases of naming therapy, one in Bengali and one in English. Each phase treated two groups of words with semantic and phonological tasks, respectively. The effects of therapy were measured with a picture-naming task involving both treated and untreated (control) items. This was administered in both languages on four occasions: two pre-therapy, one immediately post-therapy and one 4 weeks after therapy had ceased. Testing and therapy in Bengali was administered by bilingual co-workers.

OUTCOMES & RESULTS

Four of the five participants made significant gains from at least one episode of therapy. Benefits arose in both languages and from both semantic and phonological tasks. There were three instances of cross-linguistic generalisation, which occurred when items had been treated in the person's dominant language using semantic tasks.

CONCLUSIONS & IMPLICATIONS

This study suggests that 'typical' naming treatments can be effective for some bilingual people with aphasia, with both L1 and L2 benefiting. It offers evidence of cross-linguistic generalisation, and suggests that this is most likely to arise from semantic therapy approaches. In contrast to some results in the academic literature, the direction of generalisation was from LI to L2. The theoretical implications of these findings are considered. Finally, the results support the use of bilingual co-workers in therapy delivery.

[Syndromes or symptoms in the assessment of aphasic patients?]

The procedure generally used to diagnose aphasic patients consists of classifying them in one of the classic syndromes on the basis of the analysis of their symptoms. However, this taxonomy has several important problems, the main one being that it does not take into account the variability of aphasic patients, as there are many more disorder profiles than those included in the syndromes. In order to test the homogeneity of a sample of patients diagnosed with the classic taxonomy, 15 aphasic patients (5 Broca, 5 Wernicke and 5 Conduction) and 5 healthy controls were tested with nine comprehension and production tasks. Participants were aged 38 to 81 years old. The results indicate the existence of great variability in patients labeled with the same diagnosis, as revealed by the differences in within-group scores in each task, and a limited adjustment to the expected profile, with some patients showing symptoms allegedly corresponding to other syndromes. Our results call attention to the need to study each patient individually and interpret their disorders regardless of the syndromes.

Severity of post-stroke aphasia according to aphasia type and lesion location in Koreans

To determine the relations between post-stroke aphasia severity and aphasia type and lesion location, a retrospective review was undertaken using the medical records of 97 Korean patients, treated within 90 days of onset, for aphasia caused by unilateral left hemispheric stroke. Types of aphasia were classified according to the validated Korean version of the Western Aphasia Battery (K-WAB), and severities of aphasia were quantified using WAB Aphasia Quotients (AQ). Lesion locations were classified as cortical or subcortical, and were determined by magnetic resonance imaging. Two-step cluster analysis was performed using AQ values to classify aphasia severity by aphasia type and lesion location. Cluster analysis resulted in four severity clusters: 1) mild; anomic type, 2) moderate; Wernicke's, transcortical motor, transcortical sensory, conduction, and mixed transcortical types, 3) moderately severe; Broca's aphasia, and 4) severe; global aphasia, and also in three lesion location clusters: 1) mild; subcortical 2) moderate; cortical lesions involving Broca's and/or Wernicke's areas, and 3) severe; insular and cortical lesions not in Broca's or Wernicke's areas. These results revealed that within 3 months of stroke, global aphasia was the more severely affected type and cortical lesions were more likely to affect language function than subcortical lesions.

The use of main concept analysis to measure discourse production in Cantonese-speaking persons with aphasia: a preliminary report

Discourse produced by speakers with aphasia contains rich and valuable information for researchers to understand the manifestation of aphasia as well as for clinicians to plan specific treatment components for their clients. Various approaches to investigate aphasic discourse have been proposed in the English literature. However, this is not the case in Chinese. As a result, clinical evaluations of aphasic discourse have not been a common practice. This problem is further compounded by the lack of validated stimuli that are culturally appropriate for language elicitation. The purpose of this study was twofold: (a) to develop and validate four sequential pictorial stimuli for elicitation of language samples in Cantonese speakers with aphasia, and (b) to investigate the use of a main concept measurement, a clinically oriented quantitative system, to analyze the elicited language samples. Twenty speakers with aphasia and ten normal speakers were invited to participate in this study. The aphasic group produced significantly less key information than the normal group. More importantly, a strong relationship was also found between aphasia severity and production of main concepts. While the results of the inter-rater and intra-rater reliability suggested the scoring system to be reliable, the test-retest results yielded strong and significant correlations across two testing sessions one to three weeks apart.

LEARNING OUTCOMES

Readers will demonstrate better understanding of (1) the development and validation of newly devised sequential pictorial stimuli to elicit oral language production, and (2) the use of a main concept measurement to quantify aphasic connected speech in Cantonese Chinese.

Noun-verb ambiguity in chronic undifferentiated schizophrenia

This study investigated noun-verb retrieval patterns of 30 adults with chronic undifferentiated schizophrenia and 67 typical adults, to determine if schizophrenia affected nouns (associated with temporal lobe function) differently from verbs (associated with frontal lobe function). Stimuli were homophonic homographic homonyms, balanced according to frequency of occurrence, where N>V, N<V, or N approximately V. Systematicity effects, in which systematic noun and verb meanings are transparently related (e.g., "drain"), and unsystematic noun and verb meanings appear to be unrelated (e.g., "seal"), were also examined. Adults with schizophrenia overselected nouns, in both phrase and sentence tasks. Typical participants strongly preferred verbs in the phrase task, but nouns in the sentence task. Frequency of occurrence yielded statistically significant effects in control, but not in experimental groups. Effects of systematicity were statistically significant in some, but not all tasks and conditions. Age of typical participants was not significant.

LEARNING OUTCOMES

Readers will be introduced to (a) evidence of noun-verb organization in the brain; (b) evidence of ambiguous noun-verb preference to differentiate the language of schizophrenia from the language of typical adults; and (c) evidence of ambiguous noun-verb preference to differentiate the language of schizophrenia from fluent aphasia.

The relationship between semantic short-term memory and immediate serial recall of known and unknown words and nonwords: data from two Chinese individuals with aphasia

The present study investigated verbal recall of semantically preserved and degraded words and nonwords by taking into consideration the status of one's semantic short-term memory (STM). Two experiments were conducted on 2 Chinese individuals with aphasia. The first experiment showed that they had largely preserved phonological processing abilities accompanied by mild but comparable semantic processing deficits; however, their performance on STM tasks revealed a double dissociation. The second experiment found that the participant with more preserved semantic STM had better recall of known words and nonwords than of their unknown counterparts, whereas such effects were absent in the patient with severe semantic STM deficit. The results are compatible with models that assume separate phonological and semantic STM components, such as that of R. C. Martin, M. Lesch, and M. Bartha (1999). In addition, the distribution of error types was different from previous studies. This is discussed in terms of the methodology of the authors' experiments and current views regarding the nature of semantic STM and representations in the Chinese mental lexicon.

Spoken-word processing in aphasia: effects of item overlap and item repetition

Two studies were carried out to investigate the effects of presentation of primes showing partial (word-initial) or full overlap on processing of spoken target words. The first study investigated whether time compression would interfere with lexical processing so as to elicit aphasic-like performance in non-brain-damaged subjects. The second study was designed to compare effects of item overlap and item repetition in aphasic patients of different diagnostic types. Time compression did not interfere with lexical deactivation for the non-brain-damaged subjects. Furthermore, all aphasic patients showed immediate inhibition of co-activated candidates. These combined results show that deactivation is a fast process. Repetition effects, however, seem to arise only at the longer term in aphasic patients. Importantly, poor performance on diagnostic verbal STM tasks was shown to be related to lexical decision performance in both overlap and repetition conditions, which suggests a common underlying deficit.

Correlative studies of structural and functional imaging in primary progressive aphasia

RATIONALE

To compare and contrast structural and functional imaging in primary progressive aphasia (PPA).

METHODS

A cohort of 8 patients diagnosed with PPA presenting with nonfluency were prospectively evaluated. All patients had structural imaging in the form of MRI and in 1 patient CAT scanning on account of a cardiac pacemaker. All patients had single-photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging.

RESULTS

SPECT and PET imaging had 100% correlation. Anatomical imaging was abnormal in only 6 of the 8 patients. Wernicke's area showed greater peak Z score reduction and extent of area affected than Broca's area (McNemar paired test: P = .008 for Z score reduction; P = .0003 for extent). PET scanning revealed significant involvement of the anterior cingulum.

CONCLUSION

Functional imaging in PPA: (a) identified more patients correctly than anatomic imaging highlighting the importance of SPECT and PET in the diagnosis; and (b) demonstrated the heterogeneous involvement of disordered linguistic networks in PPA suggesting its syndromic nature.

Taxing working memory with syntax: bihemispheric modulations

Motivated by claims that relegate the syntactic functions of Broca's region to working memory (WM) and not to language-specific mechanisms, we conducted an fMRI and an aphasia study that featured two varieties of intrasentential dependency relations: One was syntactic movement (e.g., Which boy does the girl think [symbol in text] examined Steven?), the other was antecedent-reflexive binding (e.g., Jill thinks the boy examined himself). In both, WM is required to link two nonadjacent positions. Syntactically, they are governed by distinct rule systems. In health, the two dependencies modulated activity in distinct brain regions within the left inferior frontal gyrus and the left middle temporal gyrus. Binding uniquely modulated activation in the right frontal lobe. Receptive abilities in brain damaged patients likewise distinguished among these syntactic types. The results indicate that sentence comprehension is governed by syntactically carved neural chunks and provide hints regarding a language related region in the right hemisphere.

The trouble with nouns and verbs in Greek fluent aphasia

In the past verb retrieval problems were associated primarily with agrammatism and noun retrieval difficulties with fluent aphasia. With regards to fluent aphasia, so far in the literature, three distinct patterns of verb/noun dissociations have been described for individuals with fluent anomic aphasia in languages with different underlying forms; better verb retrieval, poorer verb retrieval and equal retrieval difficulties for verbs and nouns. Verbs and nouns in Greek are considered of similar morphological complexity thus it was predicted that anomic aphasic individuals would suffer from a non-dissociated impairment of verbs and nouns. Problems with verbs and/or nouns may arise at any stage in the process of lexical retrieval, i.e. lexical-semantic, lemma, lexeme or articulation. The aim of this research was to investigate verb and noun retrieval using a picture-naming task to explore any possible selective noun and/or verb comprehension or retrieval deficits in Greek individuals with anomic aphasia. The results revealed a significant verb/noun dichotomy with verbs significantly more difficult to retrieve than nouns. These findings lend support for the growing body of evidence showing a specific verb impairment in fluent anomic individuals as well as Broca's patients. Given the prevailing view, that anomic patients experience difficulty retrieving the morpho-phonological form of the target word, the results show that specific information of the grammatical category is also important during word form retrieval. LEARNER OUTCOMES: The reader will become familiar with (i) studies investigating grammatical word class breakdown in individuals with aphasia who speak different languages, (ii) the application of the serial model to word production breakdown in aphasia and (iii) the characteristics of verbs and nouns in Greek. It will be concluded that successful verb retrieval for fluent aphasic individuals who speak Greek is dependant on the retrieval of the morpho-phonological information of the target verb.

High risk of reading disability and speech sound disorder in rolandic epilepsy families: case-control study

PURPOSE

Associations between rolandic epilepsy (RE) with reading disability (RD) and speech sound disorder (SSD) have not been tested in a controlled study. We conducted a case-control study to determine whether (1) RD and SSD odds are higher in RE probands than controls and (2) an RE proband predicts a family member with RD or SSD, hence suggesting a shared genetic etiology for RE, RD, and SSD.

METHODS

Unmatched case-control study with 55 stringently defined RE cases, 150 controls in the same age range lacking a primary brain disorder diagnosis, and their siblings and parents. Odds ratios (OR) were calculated by multiple logistic regression, adjusted for sex and age, and for relatives, also adjusted for comorbidity of RD and SSD in the proband.

RESULTS

RD was strongly associated with RE after adjustment for sex and age: OR 5.78 (95% CI: 2.86-11.69). An RE proband predicts RD in family members: OR 2.84 (95% CI: 1.38-5.84), but not independently of the RE proband's RD status: OR 1.30 (95% CI: 0.55-12.79). SSD was also comorbid with RE: adjusted OR 2.47 (95%CI: 1.22-4.97). An RE proband predicts SSD in relatives, even after controlling for sex, age and proband SSD comorbidity: OR 4.44 (95% CI: 1.93-10.22).

CONCLUSIONS

RE is strongly comorbid with RD and SSD. Both RD and SSD are likely to be genetically influenced and may contribute to the complex genetic etiology of the RE syndrome. Siblings of RE patients are at high risk of RD and SSD and both RE patients and their younger siblings should be screened early.

CT and MRI appearance of mitochondrial encephalopathy

A case is reported of a 20-year-old female presenting with confusion and progressive sensory aphasia. CT and MRI showed bilateral and symmetric acute necrosis of the basal ganglia and of the left temporal and occipital lobe, besides chronic spinocerebellar degeneration. The imaging findings suggested a mitochrondrial encephalopathy. Genetic examination confirmed a MELAS syndrome (mitochondrial myopathy, encephalopathy, lactate acidosis and stroke like episodes).

Nasal consonant production in Broca's and Wernicke's aphasics: speech deficits and neuroanatomical correlates

The present study investigated the articulatory implementation deficits of Broca's and Wernicke's aphasics and their potential neuroanatomical correlates. Five Broca's aphasics, two Wernicke's aphasics, and four age-matched normal speakers produced consonant-vowel-(consonant) real word tokens consisting of [m, n] followed by [i, e, a, o, u]. Three acoustic measures were analyzed corresponding to different properties of articulatory implementation: murmur duration (a measure of timing), amplitude of the first harmonic at consonantal release (a measure of articulatory coordination), and murmur amplitude over time (a measure of laryngeal control). Results showed that Broca's aphasics displayed impairments in all of these parameters, whereas Wernicke's aphasics only exhibited greater variability in the production of two of the parameters. The lesion extent data showed that damage in either Broca's area or the insula cortex was not predictive of the severity of the speech output impairment. Instead, lesions in the upper and lower motor face areas and the supplementary motor area resulted in the most severe implementation impairments. For the Wernicke's aphasics, the posterior areas (superior marginal gyrus, parietal, and sensory) appear to be involved in the retrieval and encoding of lexical forms for speech production, resulting in increased variability in speech production.

Action and object processing in aphasia: from nouns and verbs to the effect of manipulability

The processing of words and pictures representing actions and objects was tested in 21 aphasic patients and 20 healthy controls across three word production tasks: picture-naming (PN), single word reading (WR) and word repetition (WRP). Analysis 1 targeted task and lexical category (noun-verb), revealing worse performance on PN and verb items for both patients and control participants. For Analysis 2 we used data collected in a concurrent gesture norming study to re-categorize the noun-verb items along hand imagery parameters (i.e., objects that can/cannot be manipulated and actions which do/do not involve fine hand movements). Here, patients displayed relative difficulty with the 'manipulable' items, while controls displayed the opposite pattern. Therefore, whereas the noun-verb distinction resulted simply in lower verb accuracy across groups, the 'manipulability' distinction revealed a 'double-dissociation' between patients and control participants. These results carry implications for theories of embodiment, lexico-semantic dissociations, and the organization of meaning in the brain.

Lexical competition effects in aphasia: deactivation of lexical candidates in spoken word processing

Research has shown that Broca's and Wernicke's aphasic patients show different impairments in auditory lexical processing. The results of an experiment with form-overlapping primes showed an inhibitory effect of form-overlap for control adults and a weak inhibition trend for Broca's aphasic patients, but a facilitatory effect of form-overlap was found for Wernicke's aphasic participants. This suggests that Wernicke's aphasic patients are mainly impaired in suppression of once-activated word candidates and selection of one winning candidate, which may be related to their problems in auditory language comprehension.

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.

Cortical laminar necrosis related to prolonged focal status epilepticus

Cortical laminar necrosis (CLN) is radiologically defined as high intensity cortical lesions on T1 weighted MRI images following a gyral distribution. Histopathologically, CLN is characterised by pannecrosis of the cortex involving neurones, glial cells, and blood vessels. It has been reported to be associated with hypoxia, metabolic disturbances, drugs, and infections. We present two patients who developed CLN and permanent neurological deficits after prolonged and repeated focal status epilepticus. The possible mechanisms leading to CLN in these patients are discussed, together with the implications of prompt and aggressive treatment in similar cases.

Processing homonymy and polysemy: effects of sentential context and time-course following unilateral brain damage

The present study investigated the abilities of left-hemisphere-damaged (LHD) non-fluent aphasic, right-hemisphere-damaged (RHD), and normal control individuals to access, in sentential biasing contexts, the multiple meanings of three types of ambiguous words, namely homonyms (e.g., "punch"), metonymies (e.g., "rabbit"), and metaphors (e.g., "star"). Furthermore, the predictions of the "suppression deficit" and "coarse semantic coding" hypotheses, which have been proposed to account for RH language function/dysfunction, were tested. Using an auditory semantic priming paradigm, ambiguous words were incorporated in dominant- or subordinate-biasing sentence-primes followed after a short (100 ms) or long (1,000 ms) interstimulus interval (ISI) by dominant-meaning-related, subordinate-meaning-related or unrelated target words. For all three types of ambiguous words, both the effects of context and ISI were obvious in the performance of normal control subjects, who showed multiple meaning activation at the short ISI, but eventually, at the long ISI, contextually appropriate meaning selection. Largely similar performance was exhibited by the LHD non-fluent aphasic patients as well. In contrast, RHD patients showed limited effects of context, and no effects of the time-course of processing. In addition, although homonymous and metonymous words showed similar patterns of activation (i.e., both meanings were activated at both ISIs), RHD patients had difficulties activating the subordinate meanings of metaphors, suggesting a selective problem with figurative meanings. Although the present findings do not provide strong support for either the "coarse semantic coding" or the "suppression deficit" hypotheses, they are viewed as being more consistent with the latter, according to which RH damage leads to deficits suppressing alternative meanings of ambiguous words that become incompatible with the context.

Neural correlates of lexicon and grammar: evidence from the production, reading, and judgment of inflection in aphasia

Are the linguistic forms that are memorized in the mental lexicon and those that are specified by the rules of grammar subserved by distinct neurocognitive systems or by a single computational system with relatively broad anatomic distribution? On a dual-system view, the productive -ed-suffixation of English regular past tense forms (e.g., look-looked) depends upon the mental grammar, whereas irregular forms (e.g., dig-dug) are retrieved from lexical memory. On a single-mechanism view, the computation of both past tense types depends on associative memory. Neurological double dissociations between regulars and irregulars strengthen the dual-system view. The computation of real and novel, regular and irregular past tense forms was investigated in 20 aphasic subjects. Aphasics with non-fluent agrammatic speech and left frontal lesions were consistently more impaired at the production, reading, and judgment of regular than irregular past tenses. Aphasics with fluent speech and word-finding difficulties, and with left temporal/temporo-parietal lesions, showed the opposite pattern. These patterns held even when measures of frequency, phonological complexity, articulatory difficulty, and other factors were held constant. The data support the view that the memorized words of the mental lexicon are subserved by a brain system involving left temporal/temporo-parietal structures, whereas aspects of the mental grammar, in particular the computation of regular morphological forms, are subserved by a distinct system involving left frontal structures.

How to improve repetition ability in patients with Wernicke's aphasia: the effect of a disguised task

Dissociation "automatico-voluntaire" is a symptom observed in aphasic patients. We elucidated the difference between voluntary and involuntary speech output in a quantitative manner using the same task materials in nine patients with Wernicke's aphasia. All the patients exhibited better ability and less paraphasias in a repetition task elicited in a disguised condition than in an ordinary repetition condition. This result indicates that the output difficulty in Wernicke's aphasia might be a disability of volitional control over the language system.

Recovery From Aphasia After Hemicraniectomy for Infarction of the Speech-Dominant Hemisphere

Background and Purpose— The space-occupying effect of cerebral edema limits survival chances of patients with severe ischemic stroke. Besides conventional therapies to reduce intracranial pressure, hemicraniectomy can be considered as a therapeutic option after space-occupying cerebral infarction. There is controversy regarding the use of this method in patients with infarction of the speech-dominant hemisphere.

Methods— In 14 patients with infarction of the dominant hemisphere and subsequent treatment with hemicraniectomy, recovery from aphasic symptoms was evaluated retrospectively. A group of patients who were treated between 1994 and 2003 in our aphasia ward was selected for the study. In all patients, a psychometric quantification was accomplished applying the Aachen Aphasia Test at least twice within a mean observation period of 470 days.

Results— A significant improvement of the statistical parameters representing different aspects of aphasia was observed in 13 of 14 patients. Also, an increase of the ability to communicate was evident in 13 patients. Young age at the time of stroke and early poststroke decompressive surgery were identified as main predictors for recovery from aphasia.

Conclusions— A significant improvement of aphasic symptoms can be observed in a preselected group of patients after a massive stroke of the speech-dominant hemisphere treated by consecutive hemicraniectomy. Therefore, decompressive surgery can be considered for the treatment of this kind of stroke.

Evolution of phonemic word fluency performance in post-stroke aphasia

In this longitudinal study, quantitative and qualitative changes in responses of people with aphasia were examined on a phonemic fluency task. Eighteen patients were tested at 3-month intervals on the letters F-A-S while they received comprehensive, intensive treatment from 3 to 12 months post-stroke. They returned for a follow-up evaluation at an average of 10 months post-intervention. Mean group scores improved significantly from beginning to end of treatment, but declined post-intervention. Patients produced a significantly greater number and proportion of modifiers (adjectives and adverbs) between the beginning and end of treatment, with no decline afterwards, implying that they had access to a wider range of grammatical categories over time. Moreover, patients used significantly more phonemic clusters in generating word lists by the end of treatment. These gains may be attributed to the combined effects of time since onset and the linguistic and cognitive stimulation that patients received in therapy.

LEARNING OUTCOMES

Readers of this paper should (1) gain a better understanding of verbal fluency performance in the assessment of aphasia, (2) recognize the importance of analyzing qualitative aspects of single word production in aphasia, and (3) contribute to their clinical judgment of long term improvement in aphasia.

Contrasting effects of phonological priming in aphasic word production

Two fluent aphasics, IG and GL, performed a phonological priming task in which they repeated an auditory prime then named a target picture. The two patients both had selective deficits in word production: they were at or near ceiling on lexical comprehension tasks, but were significantly impaired in picture naming. IG's naming errors included both semantic and phonemic paraphasias, as well as failures to respond, whereas GL's errors were mainly phonemic and formal paraphasias. The two patients responded very differently to phonological priming: IG's naming was facilitated (both accuracy and speed) only by begin-related primes (e.g. ferry-feather), whereas GL benefited significantly only from end-related primes (e.g. brother-feather), showing no more than a facilitatory trend with begin-related primes. We interpret these results within a two-stage model of word production, in which begin-related and end-related primes are said to operate at different stages. We then discuss implications for models of normal and aphasic word production in general and particularly with respect to sequential aspects of the phonological encoding process.

A meta-analytic review of verbal fluency performance following focal cortical lesions

A meta-analysis of 31 studies with 1,791 participants was conducted to investigate the sensitivity of tests of verbal fluency to the presence of focal cortical lesions. Relative to healthy controls, participants with focal frontal injuries had large and comparable deficits on phonemic (r = .52) and semantic (r = .54) fluency. For frontal but not nonfrontal patients, phonemic fluency deficits qualified as differential deficits when compared with IQ and psychomotor speed; phonemic fluency was also more strongly and more specifically related to the presence of frontal lesions than the Wisconsin Card Sorting Test scores. In contrast, temporal damage was associated with a lesser deficit on phonemic fluency (r = .44) but a larger deficit on semantic fluency (r = .61).

Crossed Wernicke's aphasia: a case report

Crossed aphasia is a phenomenon in which an individual sustains a lesion in the right hemisphere (typically non-language dominant), but who exhibits an aphasic syndrome. The authors present a case study of an individual with crossed aphasia (CA) in an attempt to provide anecdotal information for four questions posed by : (a). Is CA a reversal of the normal cerebral hemisphere pattern of language function? (b). Does the presence of aphasia following a right cerebral hemisphere lesion indicate that typical right hemisphere functions (e.g., visual perception) are intact? (c). How may the aphasia's presentation differ from typical left hemisphere aphasias? And (d). is the pattern of improvement following CA similar to that of typical left hemisphere aphasias? We longitudinally examined the communicative-cognitive performance of an adult man with crossed aphasia of the Wernicke's type following a cerebrovascular accident. A 21-week follow-up evaluation indicated improvements in his language functioning from our initial evaluation, but he continued to exhibit a classic, moderately severe Wernicke's aphasia.

Spared access to idiomatic and literal meanings: a single-case approach

The current study examines how patients with aphasia access the meanings of idioms during spoken sentence comprehension. In our experiment, we had 4 subjects whose native language is German: 2 left-hemisphere damaged patients (Wernicke's and global aphasia); 1 right-hemisphere damaged patient; and 1 age-matched healthy speaker. Ambiguous two-element German noun compounds carrying an idiomatic as well as a literal meaning served as target words. While listening to contextually biasing sentences containing the target words, the subjects performed a lexical decision task at the offset of each compound. All the subjects, including the aphasic patients, accessed the compounds' literal and idiomatic meanings simultaneously despite the existence of contextually biasing sentences. The data are discussed by taking account of the findings of recent studies of lexical semantic processing in aphasia.

Word order and finiteness in Dutch and English Broca's and Wernicke's aphasia

The effect of two linguistic factors in Broca's and Wernicke's aphasia was examined using Dutch and English subjects. Three tasks were used to test (1). the comprehension and (2). the construction of sentences, where verbs (in Dutch) and verb arguments (in Dutch and English) are in canonical versus non-canonical position; (3). the production of finite versus infinitive verbs. Proportions of errors as well as types of errors made by each aphasic group are similar on the sentence comprehension and sentence anagram tasks. On the verb production task the performance pattern is, again, the same, but the error types are different. The discussion focuses on how the similarities and differences across languages and across aphasia types may be interpreted with respect to the underlying deficit in Broca's and Wernicke's aphasia.

Deficits in thematic integration processes in Broca's and Wernicke's aphasia

This study investigated how normal subjects and Broca's and Wernicke's aphasics integrate thematic information incrementally using syntax, lexical-semantics, and pragmatics in a simple active declarative sentence. Three priming experiments were conducted using an auditory lexical decision task in which subjects made a lexical decision on a 'target' (the last word of each sentence) preceded by a 'prime' (a subject noun phrase and verb). The presence and magnitude of priming was compared to a baseline condition in which non-words systematically replaced real word primes. Normal subjects showed evidence for combinatorial thematics by exhibiting significant and larger amounts of thematic priming in the condition where two real words were present in the prime than in the conditions in which only one real word was present in the prime. Additionally, normal subjects showed sensitivity to both syntactic structures and pragmatics. In contrast, Broca's patients did not show significant priming for any condition nor did they show a difference in the magnitude of priming among the conditions. Nonetheless, they showed sensitivity to pragmatics. Wernicke's patients showed significant priming for all conditions, but did not show differences in the magnitude of priming among the conditions. However, they showed sensitivity to sentence grammaticality and pragmatics. The distinct patterns of performance of Broca's and Wernicke's aphasics are discussed in terms of the nature of their impairments in the processes of combinatorial thematics.

The Effects of Alzheimer's Disease on Item Output in Verbal Fluency Tasks

We collected category fluency data from several moderate-to-large samples of participants at three different sites: the New York University Aging and Dementia Center, the Oregon Health Services Aging and Dementia Research Center, and the Einstein Aging Study at the Albert Einstein College of Medicine. These data were analyzed by calculating the average relative frequency (e.g., typicality) of the category members generated by each participant. Alzheimer's disease (AD) patients recalled fewer atypical members of common taxonomic categories than did the elderly control group. In addition, the probability of producing an item declined at a greater rate for AD patients than for the elderly control group over the duration of the task. According to sequential sampling models, this latter result implies that the rate at which AD patients search memory must be slower than the search rate of the elderly controls.

Effect of typicality on online category verification of animate category exemplars in aphasia

Normal young, elderly, Broca's aphasic, and Wernicke's aphasic individuals participated in an online category verification task where primes were superordinate category labels while targets were either typical or atypical examples of animate categories or nonmembers belonging to inanimate categories. The reaction time to judge whether the target belonged to the preceding category label was measured. Results indicated that all four groups made significantly greater errors on atypical examples compared to typical examples. Young and elderly individuals, and Broca's aphasic patients performed similarly on the verification task; these groups demonstrated faster reaction times on typical examples than atypical examples. Wernicke's aphasic patients made the most errors on the task and were slowest to respond than any other participant group. Also, these participants were not significantly faster at accepting correct typical examples compared to correct atypical examples. The results from the four groups are discussed with relevance to prototype/family resemblance models of typicality.

Effect of lexical cues on the production of active and passive sentences in Broca's and Wernicke's aphasia

This study compared the sentence production abilities of individuals with Broca's and Wernicke's aphasia in an attempt to explore the extent to which impaired lexical retrieval impedes sentence production. The ability to produce active and passive reversible and non-reversible sentences was examined when varying amounts of lexical information was provided. The results showed that both Wernicke's and Broca's aphasic individuals were impaired in passive sentence production and that these difficulties were not overcome when lexical cues (the relevant nouns and uninflected verb) were provided. However when auxiliary and past tense morphemes were provided along with the verb stem, production of passive sentences improved drastically for both groups. Analysis of error patterns, however, revealed differences between the two groups, suggesting that Broca's aphasic subjects may find passive sentences difficult due to problems with retrieving the relevant grammatical morphemes. Subjects with Wernicke's aphasia may have been unable to automatically access the passive sentence structure.

Phoneme frequency effects in jargon aphasia: a phonological investigation of nonword errors

This study investigates the nonwords produced by a jargon speaker, LT. Despite presenting with severe neologistic jargon, LT can produce discrete responses in picture naming tasks thus allowing the properties of his jargon to be investigated. This ability was exploited in two naming tasks. The first showed that LT's nonword errors are related to their targets despite being generally unrecognizable. This relatedness appears to be a general property of his errors suggesting that they are produced by lexical rather than nonlexical means. The second naming task used a set of stimuli controlled for their phonemic content. This allowed an investigation of target phonology at the level of individual phonemes. Nonword responses maintained the English distribution of consonants and showed a significant relationship to the target phonologies. A strong influence of phoneme frequency was identified. High frequency consonants showed a pattern of frequent but indiscriminate use. Low frequency consonants were realised less often but were largely restricted to target related contexts rarely appearing as error phonology. The findings are explained within a lexical activation network with the proposal that the resting levels of phoneme nodes are frequency sensitive. Predictions for the recovery of jargon aphasia and suggestions for future investigations are made.

Summation priming in aphasia: evidence for alterations in semantic integration and activation

The present study used a lexical decision paradigm to study the summation of priming effects in normal and aphasic participants. The amount of priming produced by pairs of definitionally converging associative words was compared to the amount of priming produced by pairs of single associative words and non-words in two experiments in which the ISI between primes and targets varied from 200 ms (Experiment 1) to 600 ms (Experiment 2). Control subjects showed a pattern of additive summation priming at the short ISI and overadditive summation priming at the longer ISI. Broca's aphasics showed overadditive priming at the short ISI and no significant priming at the longer ISI; Wernicke's aphasics showed no significant priming at the short ISI and additive priming at the longer ISI. These results suggest that aphasics differ from normals in their ability to integrate the activation derived from multiple linguistic associations and may provide an account of some of the clinical phenomenology of these patients.

Verbal fluency in Huntington's disease: a longitudinal analysis of phonemic and semantic clustering and switching

Two underlying components of verbal fluency tasks have been identified as clustering (the ability to generate successive words within a sub-category) and switching (the ability to shift from one sub-category to another). Selective impairment of switching ability occurs in patients with frontostriatal pathology, whilst clustering ability is compromised with temporal lobe dysfunction. Letter fluency tasks have been shown to be especially sensitive to frontostriatal deficits, whereas, category fluency tasks tend to be compromised by temporal lobe pathology. This study examined two types of verbal fluency task (letter fluency and category fluency) using two levels of analysis (phonemic and semantic) for clustering and switching measures. The performance of 21 frontostriatally compromised Huntington's disease (HD) patients was followed over an average of 3.5 annual follow-up visits. HD patients showed a significant reduction of correctly generated words over time, together with a significant increase in word repetitions. Phonemic switching decreased significantly over time for both letter and category fluency. Semantic switching, however, remained stable over time for both verbal fluency tasks. Clustering (both semantic and phonemic) likewise remained stable and did not vary longitudinally for either letter or category fluency. Hence, phonemic switching alone drove verbal fluency performance and this selective impairment can be explained by the progressive involvement of frontostriatal circuitry in the natural progression of HD.

A callosal transfer deficit in children with developmental language disorder

Twenty-two control children (aged 6-12 years) and forty-three children with developmental language disorder (DLD) (aged 7-12 years) received a test of callosal transfer of tactile information. Among the children with dysphasia, 30 had a diagnosis of receptive dysphasia and 13 of expressive dysphasia. Both control children and children with DLD made a significantly larger number of errors in the crossed localization condition (implying callosal transfer of tactile information) versus the uncrossed localization condition. In the crossed localization condition, children with DLD made a significantly larger number of errors than controls, while no differences were found in the two groups of children with DLD. These data suggest that the corpus callosum may be involved in the pathogenesis of DLD.

Verb-noun double dissociation in aphasic lexical impairments: the role of word frequency and imageability

Neurolinguistic studies have provided important evidence regarding the organization of lexical representations and the structure of underlying conceptual knowledge; in particular, it has been shown that the retrieval of verbs and nouns can be damaged selectively. Dissociated lexical damage is proof of an independent mental organization of lexical representations and/or of the underlying processes. The aim of the present study is to estimate the rate of dissociated impairments for nouns and verbs on a large sample of mild to moderate aphasic patients and to investigate the mechanisms underlying such phenomena. In addition, the authors wished to verify to what degree the impairment for nouns and verbs is related to a specific type of language disorder. A confrontation naming task for verbs and nouns was administered to 58 aphasic patients. The major lexical (word frequency and age of acquisition) and semantic variables (familiarity and imageability of the underlying concept) were considered for each noun and verb used in the task. Verbs were distinguished by major functional classes (transitive, intransitive, and ergative verbs). The data collected from this task were analyzed twice: (i) as a group study comparison of major aphasic subgroups and (ii) as a multiple single case study to evaluate the differences on the naming of verbs and nouns and the effect of the lexical semantic variables on each individual patient. The results confirm the existence of dissociated naming impairments of verbs and nouns. Selective impairment of verbs is more frequent (34%) than that of nouns (10%). In many cases, the dissociated pattern of naming impairment disappeared when the effect of the concomitant variables (word frequency and imageability) was removed, but in approximately one-fifth of the cases the noun or verb superiority was preserved. Noun superiority emerged in five of six agrammatic patients. Both the naming of verbs (n = 9) or of nouns (n = 6) could be impaired selectively in fluent aphasic patients. The results lend support to the hypothesis of an independent mental organization of nouns and verbs, but a substantial effect of imageability and word frequency suggests an interaction of the naming impairment with underlying lexical and semantic aspects.