Lexical Retrieval Difficulties Research Articles

Do gestures reflect children’s lexical retrieval difficulties?

Abstract According to the Lexical Retrieval Hypothesis, one important function of representational gestures is to help speakers retrieve words for production. In this study, we test whether gestures help preschoolers access words for production. We tested two predictions generated from the LRH. First, since bilinguals often have greater difficulties with lexical access than monolinguals, we predicted that bilinguals will gesture more than monolinguals. Second, since low-frequency words are harder to access than high frequency words, we predicted that the more low-frequency words children used, the more they would gesture. Using children’s (aged 4 to 6 years) data from a storytelling task, we found no difference in gesture use between bilinguals and monolinguals. We did, however, find that the use of low-frequency words was a positive predictor of gesture use. While this result could support the LRH, an exploration of some examples of gesture production raises some doubts about that conclusion.

Comparing Individuals With PPA to Individuals With AD: Cognitive and Linguistic Profiles

Primary Progressive Aphasia (PPA) is a degenerative condition characterized by the progressive loss of language function. In PPA, aphasia is the most prominent deficit at onset. On the other hand, memory deficits are the hallmark of Alzheimer's disease (AD). The first aim of the study was to establish differences on neuropsychological testing and connected speech production between Greek-speaking individuals with AD and PPA. The second aim was to investigate the executive deficit involvement in the two conditions. Ten individuals with PPA and 9 individuals with AD took part in a comprehensive cognitive-linguistic evaluation. Fifteen demographically matched neurologically healthy adults served as controls. Participants were evaluated using a battery of neuropsychological measures. Quantitative production analysis and acoustic analysis were performed to calculate narrative and temporal measures of the participants' speech. Participants with PPA differed significantly from participants with AD on linguistic measures. They performed worse on the long frequent sentences' subtest of the Sentence Repetition Test and they produced fewer narrative and unique words in picture description. They also produced shorter, less elaborated sentences, and made more phonological errors. The two groups did not differ significantly on memory, executive, visuospatial and semantic composite measures. Compared to neurotypical adults, participants with AD were impaired in memory, and executive function. They also exhibited lexical retrieval difficulties, as well as difficulties in linguistic tasks with an increased processing load. Participants with PPA performed within normal limits on the delay conditions of episodic memory measures. However, they too were impaired in executive tasks, especially for short-term memory and verbal fluency. The production of phonological errors, difficulty in repeating long frequent sentences, and the production of simple and short sentences has differentiated participants PPA not only from neurotypical controls but also from participants with AD. No single measure could differentiate the AD group from the other two groups. These findings should be interpreted with caution considering the small sample size.

Factors affecting cross-language activation and language mixing in bilingual aphasia: A case study

ABSTRACT Background Some bilinguals with aphasia tend to mix languages within a single utterance. Two opposing views attribute this to difficulty with either language control or word retrieval. Aims This study investigated the influence of factors that increase activation of the non-target language on the occurrence of language mixing errors. This increased activation predicts more language mixing errors if there is a language control issue, but not if they stem from word retrieval difficulties. Methods and procedures A picture naming experiment was conducted with a bilingual individual with aphasia who showed language mixing. We investigated the influence of four factors likely to influence activation of representations of the non-target language on response accuracy, response latency and the occurrence of language selection errors: language, language mode, task, and phonological overlap between the target word and its translation equivalent. Outcomes and results The increased activation of the non-target language induced by language mode, task and phonological overlap with the translation equivalent did not lead to an increase in language selection errors when compared to correct responses. This is despite the fact that these factors affected accuracy and response latency, in the direction that is expected in unimpaired bilingual performance. Conclusions Results were not consistent with a disruption of the cognitive control needed to respond in the intended language. Instead, they highlight that language mixing in this individual, rather than being “pathological”, is instead used as a strategy to potentially improve communication when lexical retrieval difficulties occur. Language mixing behaviours in aphasia may not be due to issues of control and have a communicative value that should be recognised.

Lexical Retrieval Difficulties in the L1 of Lithuanians in Ireland

The article describes the study of the Irish Lithuanian (IL) L1 lexical attrition. Several indications can show lexical attrition: vocabulary reduction, use of hypernyms instead of hyponyms, code switching, and hesitation markers. These signs indicate that the person is having difficulty retrieving words from memory. The article analyzes 30 IL speech examples (recordings of picture description) while focusing on the hesitation markers (pauses, corrections, repetitions, etc.) and the units of lexical expression. The study involves first-generation emigrants who left Lithuania at the age of 12 or older and have lived in Ireland for 5 years or more. The data of the target group are compared with the data of the control group – Lithuanians living in Lithuania (LL). The significance of the results is confirmed by applying T test.
 During the study, informants were asked to describe two pictures. The results show that there were more hesitation markers in IL speech rather than in LL speech (p = 0.000). In addition, less relevant units of lexical expression were used in IL rather than in LL speech (p = 0.002). Such results suggest that the target group experience difficulties retrieving words from memory and this could mean that their L1 lexicon is facing attrition. It also turned out that the picture related to private life situations was described more fluently than the picture related to public life situations.

Aphasia assessment: impact of material on naming performance.

Naming and lexical retrieval difficulties are common symptoms of aphasia. Naming abilities are usually evaluated by means of real objects or pictures or line drawings that are printed. The aim of this study was to investigate whether the ability to name objects among individuals with aphasia is influenced by the dimensions of the visual stimuli and to understand whether the order of presentation of the stimuli, number of years of education and length of time post-onset are involved in the success of naming. The naming abilities of healthy controls and patients with acute or chronic aphasia due to stroke were assessed through presentation of two sets of 24 stimuli consisting of real objects and color photographs of the same objects presented on a screen. The results obtained under these two conditions were compared by means of within-subject paired ANOVA, controlling for presentation order. 40 patients (62.4 ± 17.3 years old; 70% females; mean education level of 8.5 ± 5.3 years; and 60% evaluated within the first eight days after stroke) and 50 controls that were age, gender and education-matched were included. Object naming was significantly better than naming color photographs among the patients (p = 0.001), but no differences were observed among the controls. Age, education, length of time post-onset and presentation sequence did not have any impact on naming performance. These results suggest that use of digital color photographs for naming objects in assessment of aphasia may be associated with lower naming performance, compared with use of real objects. This needs to be taken into account when different forms of stimuli are presented in sequential aphasia evaluations.

Apathy and actions- another consideration when theorizing about embodied nature of language in Parkinson's disease

Objectives Individuals with Parkinson's disease (PD) have difficulty processing actions or verbs relative to nouns. Verb difficulties are thought to represent the coupling of language and motor networks. However, those with PD also frequently experience apathy. The overlap between apathy and action language difficulties is to date unexplored. Furthermore, whether verb/action fluency difficulty represents verb degradation (semantic/conceptual) or a selective lexical retrieval difficulty has not been determined.Methods In the current study, 20 individuals with PD without dementia completed cued action (verb) and animal (noun) fluency tasks in addition to assessments of apathy, cognition, and motor functioning.Results Individuals who exhibited impairments on action and animal fluency improved around 50% with the provision of cueing. The degree to which action fluency improved with cueing was correlated with behavioral/initiation apathy (rs=.56) as well as motor dysfunction (rs=-.57), while no similar relationship was found between those factors and nouns.Conclusions These findings suggest that impaired retrieval of actions and nouns are present in PD, but may have different underlying neuropsychological underpinnings. This provides preliminary support for grounded cognition models, which suggest the brain organizes information around motor, perceptual, and other networks.MESH terms Parkinson Disease, Neurocognitive Disorders, Apathy, Language Disorders, Neuropsychological Tests, Cognition

Patterns of cortical interactivity supporting speech production and lexical retrieval: A graph signal processing approach at the individual level

Abstract Although seemingly easy, speech production is a complex action involving several processes and brain regions and is often studied through the use of picture naming paradigms. Several brain regions have been identified as being involved in speech production and lexical retrieval, including several areas of the left lateral, ventral, and medial temporal cortex, and of the left lateral and medial prefrontal cortex (PFC). However, little is known about how these regions interact to allow us to produce and retrieve words so efficiently as we speak. In this study, we used graph signal processing, and in particular graph learning, to analyze intracranial electroencephalography data recorded directly at the cortical surface (i.e., electrocorticography, ECoG) in the blocked cyclic picture naming task (recently reported in Ries et al., 2017). In this task, pictures are named several times in semantically homogeneous (HOM) versus heterogeneous (HET) blocks. Lexical retrieval, and in particular our ability to select words from competing alternatives, is hampered in HOM vs. HET blocks with increasing repetitions of the pictures, an effect referred to as the semantic interference effect. The method we used can infer the connectivity between different brain regions from the recorded ECoG signals through an optimization process that considers the entire connectivity map instead of pair-wise methods such as more commonly used correlation measures. Our results show that distant left frontal and temporal brain regions as well as PFC regions are functionally connected in picture naming, and that connection strength is variable between pairs of brain regions and between participants. Semantic interference on naming latencies was not present in all participants and varied in terms of when naming latencies became slower in HOM versus HET blocks. Connection weights were generally sensitive to semantic context in the participants showing a semantic interference effect on behavior but in highly variable ways across participants and in different region pairs. In sum, our results are consistent with the hypotheses that left frontal and temporal regions are functionally connected during picture naming and that intra-frontal connections seem particularly important in this paradigm manipulating lexical retrieval difficulty. Further research is needed to explore the cortical interactions supporting lexical retrieval.

Referential adjustment during discourse production in Alzheimer’s disease

ABSTRACT Several studies have shown that people with Alzheimer’s disease (AD) tend to use more pronouns than healthy aged adults when referring to entities during discourse. This referential behavior has been associated with the decrease of cognitive abilities, such as lexical retrieval difficulties or reduced abilities in working memory. However, the influence of certain important discourse factors on the referential choices made by people with AD has yet to be established. This study examines referential choices made at three discourse stages during narrative discourse (the introduction of a referent, the maintaining of the referent in focus, and the shift from one referent in focus to another). These referential choices are examined in increasingly complex referential contexts. In addition, this study investigates the relationships between referential choices and various cognitive abilities. To do so, the narrative discourses of 21 people with AD and 21 healthy adults were elicited using a newly developed storytelling in sequence task. The analyses focused on the production of three major referential expressions (indefinite expressions, definite expressions and pronouns) which are expected to vary according to discourse stage and the referential complexity of the stories. The results show that AD participants produce significantly fewer of the referential expressions expected at the introduction and shift stages than healthy aged adults produce. Nevertheless, the variation in the categories of referential expressions produced by the AD participants between the discourse stages is similar to that produced by the healthy aged adults, suggesting a preserved sensitivity to the factors manipulated in the task (i.e., discourse stages and referential complexity). This study also highlights the fact that different cognitive competences, especially executive abilities, are greatly involved in referential choices. The results add further evidence that referential choices rely on a variety of cognitive skills, depending on the discourse context in which they are made.

Evaluating Change in the Conversation of a Person With Mild Aphasia After Attentive Reading With Constrained Summarization-Written Treatment.

Purpose The purpose of this project was to evaluate the effect of a discourse-level treatment, Attentive Reading with Constrained Summarization-Written (ARCS-W), on conversational discourse. ARCS-W aims to improve spoken and written output by addressing the cognitive-linguistic requirements of discourse production through constrained summarization of novel material. Method This is an experimentally controlled case study with a single participant, Bill. Three conversation samples were collected at pretreatment, and a single conversation was collected 1 month after treatment. The participant completed 24 ARCS-W treatment sessions, and each session included reading and then summarizing a novel current event article following specific constraints (use lexically precise words, stay on topic, use complete sentences) in speaking and writing. Conversation outcomes evaluated the success of each utterance (1-4 scale), grammaticality, and the proportion of utterances with relevant content (relevant utterances). Additionally, behavioral manifestations of word-finding difficulty were evaluated in conversation. Results Bill improved communicative success at the utterance level based on the minimal detectable change. He also demonstrated reductions in behavioral manifestations of lexical retrieval difficulty based on decreases in the percentage of false starts (e.g., t*, t*), mazes (e.g., uh, s*, um), and abandoned utterances. Bill did not increase the proportion of relevant utterances or grammatical utterances in conversation. Conclusions This case study provides preliminary evidence of the potential impact of ARCS-W treatment in conversation. Additionally, the measures implemented to evaluate conversation represent a promising adaptation of a novel methodology to capture change in conversation. Supplemental Material https://doi.org/10.23641/asha.12375053.

When phonological neighborhood density both facilitates and impedes: Age of acquisition and name agreement interact with phonological neighborhood during word production.

The number of similar-sounding words that a target word has, or its Phonological Neighborhood Density (PND), has been shown to influence word production. However, reported results are sometimes inconsistent, with studies showing facilitation, inhibition, and null effects of phonological neighbors. These mixed results may be due to the influence of other factors beyond PND. We investigated the potential interactions between a broad measure of PND (bPND), and age of acquisition (AoA), frequency, and name agreement in order to see if the effect of bPND varies as a function of these three variables. We examined the effect of bPND on the latency of picture naming and observed significant interactions between bPND and AoA such that bPND facilitated lexical retrieval for words that were acquired early, but inhibited retrieval for words acquired later in life. We hypothesize that lexical retrieval difficulty ultimately depends on the activation level of the target word's phonological representations relative to the activation levels of its neighbors' phonological representations. When phonological features of the target word are weakly activated (i.e., late AoA), and bPND is high, the neighbors' activation may overshadow the target's, impeding target retrieval. However, when the target's phonological representation is strongly activated, the activation of the neighbors might not exceed that of the target, thereby supporting phonological retrieval. We also observed interactions between bPND and name agreement such that increasing bPND led to faster reaction times (RTs), particularly when name agreement was lower, suggesting that bPND may also facilitate word retrieval when lexical competition is high.

Learners’ harmonic preferences are modulated by lexical retrieval difficulty

Typological work has established the existence of language universals – features or combinations of features that (co-) occur in unrelated languages more frequently than expected by chance. The origins of language universals are a fundamental question in language sciences as these universals are considered a reflection of cognitive mechanisms underlying human language. In this study, we use a miniature artificial language learning paradigm to explore whether a well-known universal – a preference for harmonic word ordering between adpositional and verb phrases (i.e., placing the head in a consistent position with respect to the complements across the two phrase types) – originates in biases during language learning and whether this preference interacts with memory constraints (operationalized as lexical retrieval difficulty). We first trained participants on miniature languages containing adpositional phrases of a deterministic word order (either prepositional or postpositional inputs) and then briefly exposed them to simple transitive sentences (verb-subject-object and subject-object-verb order, equally frequent in the input). At test, we asked learners to describe simple transitive scenes. We found that in the hard lexical retrieval condition, learners exposed to a postpositional language showed a preference for harmonic ordering but learners of the prepositional language did not, which is only partially consistent to the typological distribution. In the easy lexical retrieval condition, learners of neither the postpositional nor prepositional language showed a preference for harmonic ordering, indicating that this preference is modulated by memory constraints.

Modified semantic feature analysis for anomia: a single case study

ABSTRACTSemantic feature analysis (SFA) is a treatment approach designed for patients with lexical retrieval difficulty caused by semantic deficits. During training, a structured framework (e.g. requiring the patient to name the category, function, and colour of the target items) is usually provided to facilitate the patient in thinking of the semantic features of the target items. Nevertheless, the use of a structured framework potentially limits the variety of semantic features activated for lexical retrieval. This study investigated the effectiveness of modified SFA training to address this potential limitation. An odd-man-out task was carried out in the modified SFA training with an anomic patient with impaired access to the phonological output lexicon. The task aimed to encourage a detailed comparison of semantic features among items in the same category. It is hypothesized that activations of more distinctive semantic features belonging to the target items will result in greater extent of generalizations in the lexical processing. The patient’s abilities in naming semantic features at the beginning and at the end of each treatment session were compared. Besides, accuracy and error patterns in oral and written naming in the initial and post-treatment assessment were also compared. The results showed a significant increase in the number of semantic features retrieved within treatment sessions. Moreover, a significant improvement in oral picture naming was also observed subsequent to the modified SFA training. Finally, the results of the error analyses further supported that the modified SFA was effective in promoting overall lexical processing. The findings indicated that both quantity and distinctiveness of concepts activated in the semantic system are essential to effective lexical retrieval. Theoretical and clinical implications were also discussed.

Conversation in Aphasia Across Communication Partners: Exploring Stability of Microlinguistic Measures and Communicative Success.

Purpose The aim of this study was to determine if people with aphasia demonstrate differences in microlinguistic skills and communicative success in unstructured, nontherapeutic conversations with a home communication partner (Home-P) as compared to a speech-language pathologist communication partner (SLP-P). Method Eight persons with aphasia participated in 2 unstructured, nontherapeutic 15-minute conversations, 1 each with an unfamiliar SLP-P and a Home-P. Utterance-level analysis evaluated communicative success. Two narrow measures of lexical relevance and sentence frame were used to evaluate independent clauses. Two broad lexical and morphosyntactic measures were used to evaluate elliptical and dependent clauses and to evaluate independent clauses for errors beyond lexical relevance and sentence frame (such as phonological and morphosyntactic errors). Utterances were further evaluated for presence of behaviors indicating lexical retrieval difficulty (pauses, repetitions, and false starts) and for referential cohesion. Results No statistical differences occurred for communicative success or for any of the microlinguistic measures between the SLP-P and Home-P conversation conditions. Four measures (2 of lexical retrieval and 1 each of communicative success and grammaticality) showed high correlations across the 2 conversation samples. Individuals showed variation of no more than 10 percentage points between the 2 conversation conditions for 46 of 56 data points. Variation greater than 10 percentage points tended to occur for the measure of referential cohesion and primarily for 1 participant. Conclusions Preliminary findings suggest that these microlinguistic measures and communicative success have potential for reliable comparison across Home-P and SLP-P conversations, with the possible exception of referential cohesion. However, further research is needed with a larger, more diverse sample. These findings suggest future assessment and treatment implications for clinical and research needs. Supplemental Material https://doi.org/10.23641/asha.7616312.

Semantic and phonological aspects of lexical retrieval in bilingual aphasia

Semantic and phonological aspects of lexical retrieval in bilingual aphasia

Language mixing patterns in a bilingual individual with non-fluent aphasia

ABSTRACTBackground: Language mixing in bilingual speakers with aphasia has been reported in a number of research studies, but the reasons for the mixing and whether it reflects typical or atypical behaviour has been a matter of debate.Aims: In this study, we tested the hypothesis that language mixing behaviour in bilingual aphasia reflects lexical retrieval difficulty.Methods & procedures: We recruited a Hebrew-English bilingual participant with mild-moderate non-fluent agrammatic aphasia and assessed his languages at three timepoints. We analysed the participant’s Hebrew and English production for retrieval during single-word naming, sentences, and discourse, and identified all instances of language mixing.Outcomes & Results: We found that there was a greater frequency of language mixing during production of more difficult lexical items, namely the post-morbidly less proficient language (compared to the more proficient language), function words (compared to content words), and single-word naming (compared to retrieval in the context of connected speech tasks), but not for verbs (compared to nouns).Conclusions: In this bilingual participant with non-fluent aphasia, language mixing behaviour closely resembles lexical retrieval difficulty. Thus, we suggest that bilingual speakers with aphasia may mix their languages as a strategy to maximise communication.

Verbal fluency performance in Bengali-English bilingual aphasia

Event Abstract Back to Event Verbal fluency performance in Bengali-English bilingual aphasia Abhijeet Patra1 and Arpita Bose1* 1 University of Reading, School of Psychology and Clinical Language Sciences, United Kingdom Introduction: Research has shown that impairments in executive control may influence word production abilities in aphasia[1,2]. However, studies investigating the contribution of lexical retrieval and executive control processes during word production are mostly limited to monolingual aphasia[3,4]. Very little is known about bilinguals with aphasia (BWA). A better approach to understand the relationship between lexical retrieval and executive control processes might be to use a task that simultaneously draw upon these processes. In a verbal fluency task, lexical and executive contribution for semantic and letter fluency conditions are different; semantic fluency largely depends on lexical retrieval abilities, whilst letter fluency largely depends on executive control abilities. Characterisation of verbal fluency performance beyond number of correct responses (CR) (e.g., Fluency Difference Score FDS; cluster size; number of switches; temporal measures such as within- and between-cluster pauses), have enabled researchers to specifically speculate the components of performance that depends on lexical retrieval vs. executive control processes[5,6,7]. Previous research has shown that in semantic fluency, BWA produced fewer CR, smaller cluster sizes, and fewer number of switches compared to bilingual healthy adults (BHA)[5,6]. These studies have emphasised the greater role of lexical processes in performance differences between BWA and BHA. However, in absence of comparison to letter fluency, it remains inconclusive if it is only the lexical processes that are compromised in BWA. We compared semantic and letter fluency conditions between Bengali-English BWA and BHA to determine: a) if poor performance in aphasia is due to lexical retrieval and/or executive control difficulties; b) are the differences more exaggerated on measures which depend heavily on the executive control processes. Bengali is a South-Asian language spoken by 180.5 million speakers in the world[8]. Despite that aphasia research reporting Bengali speakers remain under-presented (only one study)[9]. We attempt to fill this gap in the literature. Methods & Procedure: Semantic (animals, fruits and vegetables) and letter fluency (/p/, /k/, /m/) 60-seconds trails were collected from eight non-fluent Bengali-English BWA and eight Bengali-English BHA in their dominant language (Bengali). The groups were matched for age, gender, years of education, and bilingualism measures (language proficiency, usage, dominance). We measured: CR, FDS ((CR.semantic fluency - CR.letter fluency)/CR.semantic fluency), cluster size, number of switches, within-and between-cluster pause. Results and Discussion: Table 1 presents results summary. Overall, on both fluency conditions, compared to BHA, BWA produced fewer number of CR, had higher FDS, made fewer switches, and had longer between-cluster pauses. These results are indicative of difficulty in the executive control component of the verbal fluency task in addition to their lexical difficulties[4,7]. Both groups performed similarly on cluster size and within-cluster pauses. Fewer number of CR, and fewer switches for BWA are consistent with the literature[5,6]. No difference in cluster size and within-cluster pause suggest similar search strategies used by BWA and BHA while accessing the mental lexicon. Our results demonstrate that inclusion of letter fluency and a full range of verbal fluency measures are necessary to understand the effect of lexical and executive control processes in verbal fluency performance. Acknowledgements We would like to thank all our participants for their time and effort. We also would like to acknowledge Felix trust, UK for the PhD fellowship.

What we can learn from naming errors of children with language impairment at preschool age

ABSTRACTNaming is a complex, multi-level process. It is composed of distinct semantic and phonological levels. Children with naming deficits produce different error types when failing to retrieve the target word. This study explored the error characteristics of children with language impairment compared to those with typical language development. 46 preschool children were tested on a naming test: 16 with language impairment and a naming deficit and 30 with typical language development. The analysis compared types of error in both groups. In a group level, children with language impairment produced different error patterns compared to the control group. Based on naming error analysis and performance on other language tests, two case studies of contrasting profiles suggest different sources for lexical retrieval difficulties in children. The findings reveal differences between the two groups in naming scores and naming errors, and support a qualitative impairment in early development of children with naming deficits. The differing profiles of naming deficits emphasise the importance of including error analysis in the diagnosis.

Word retrieval in connected speech in Alzheimer’s disease: a review with meta-analyses

ABSTRACTBackground: Language assessment in Alzheimer’s disease (AD) demonstrates deficits in single-word production, but rarely includes connected speech.Aims: If Alzheimer’s disease leads to deficits in lexical retrieval, we should find reduced word output in connected speech, limited lexical diversity, an increase in retrieval errors, and an association between scores on tests of single-word production and measures of word retrieval in context. The purpose of this review was to investigate these hypotheses across studies of connected speech in AD.Main Contribution: A search of Medline and PsychNET identified 51 articles (published in 1985–2016) that reported data from 1,114 individuals with AD and 1,280 cognitively healthy individuals. A meta-analysis showed a significant but small reduction in word output in AD. No consistent decrease in the proportion of unique words was documented, but there was indication that individuals with AD produce more frequent words than do controls. An analysis of errors documented a moderate effect size, showing that individuals with AD commit more retrieval errors of all types. A relatively strong association was found between picture-naming scores and measures of word retrieval in connected speech.Conclusions: The review shows that individuals with AD experience significant lexical retrieval difficulties in connected speech.

Clinical marker for Alzheimer disease pathology in logopenic primary progressive aphasia.

To determine whether logopenic features of phonologic loop dysfunction reflect Alzheimer disease (AD) neuropathology in primary progressive aphasia (PPA). We performed a retrospective case-control study of 34 patients with PPA with available autopsy tissue. We compared baseline and longitudinal clinical features in patients with primary AD neuropathology to those with primary non-AD pathologies. We analyzed regional neuroanatomic disease burden in pathology-defined groups using postmortem neuropathologic data. A total of 19/34 patients had primary AD pathology and 15/34 had non-AD pathology (13 frontotemporal lobar degeneration, 2 Lewy body disease). A total of 16/19 (84%) patients with AD had a logopenic spectrum phenotype; 5 met published criteria for the logopenic variant (lvPPA), 8 had additional grammatical or semantic deficits (lvPPA+), and 3 had relatively preserved sentence repetition (lvPPA-). Sentence repetition was impaired in 68% of patients with PPA with AD pathology; forward digit span (DF) was impaired in 90%, substantially higher than in non-AD PPA (33%, p < 0.01). Lexical retrieval difficulty was common in all patients with PPA and did not discriminate between groups. Compared to non-AD, PPA with AD pathology had elevated microscopic neurodegenerative pathology in the superior/midtemporal gyrus, angular gyrus, and midfrontal cortex (p < 0.01). Low DF scores correlated with high microscopic pathologic burden in superior/midtemporal and angular gyri (p ≤ 0.03). Phonologic loop dysfunction is a central feature of AD-associated PPA and specifically correlates with temporoparietal neurodegeneration. Quantitative measures of phonologic loop function, combined with modified clinical lvPPA criteria, may help discriminate AD-associated PPA.

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

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. 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). 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. 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. 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.