Reliability of the picture description task of the Western Aphasia Battery - revised in Laurentian French persons without brain injury

Objective: Limited normative data (including psychometric properties) are currently available on discourse tasks in non-dominant languages such as Laurentian (Quebec) French. The lack of linguistic and cultural adaptation has been identified as a barrier to discourse assessment. The main aim of this study is to document inter-rater and test-retest reliability properties of the picnic scene of the Western Aphasia Battery - Revised (WAB-R), including the cultural adaptation of an information content unit (ICU) list, and provide a normative reference for persons without brain injury (PWBI). Method: To do so, we also aimed to adapt an ICU checklist culturally and linguistically for Laurentian French speakers. Discourse samples were collected from 66 PWBI using the picture description task of the WAB-R. The ICU list was first adapted into Laurentian French. Then, ICUs and thematic units (TUs) were extracted manually, and microstructural variables were extracted using CLAN. Inter-rater reliability and test-retest reliability were determined. Results: Excellent inter-rater reliability was obtained for ICUs and TUs, as well as for all microstructural variables, except for mean length of utterance, which was found to be good. Conversely, test-retest reliability ranged from poor to moderate for all variables. Conclusion: The present study provides a validated ICU checklist for clinicians and researchers working with Laurentian French speakers when assessing discourse with the picnic scene of the WAB-R. It also addresses the gap in available psychometric data regarding inter-rater and test-retest reliability in PWBI.

Speech Acts as a Window to the Difficulties in Instrumental Activities of Daily Living: A Qualitative Descriptive Study in Mild Neurocognitive Disorder and Healthy Aging

Background

Executive functions (EF) are central to instrumental activities of daily living (IADL). A novel approach to the assessment of the impact of EF difficulties on IADL may be through the speech acts produced when performing IADL-inspired tasks in a laboratory-apartment. Speech acts may act as a window to the difficulties encountered during task performance.

Objective

We aim to 1) qualitatively describe the speech acts produced by participants with mild neurocognitive disorder (mild NCD) and healthy controls (HC) as they performed 4 IADL-inspired tasks in a laboratory-apartment, and to then 2) compare their use in both groups.

Methods

The participants' performance was videotaped, and speech acts produced were transcribed. Qualitative description of all speech acts was performed, followed by a deductive-inductive pattern coding of data. Statistical analyses were performed to further compare their use by mild NCD participants and HC.

Results

Twenty-two participants took part in the study (n mild NCD = 11; n HC = 11). Meta-categories of data emerged from pattern coding: strategies, barriers, reactions, and consequences. Mild NCD participants used significantly more strategies and barriers than did HC. They were more defensive of their performance, and more reactive to their difficulties than HC. Mild NCD participants' verification of having completed all tasks was less efficient than controls.

Conclusions

An assessment of speech acts produced during the performance of IADL-inspired tasks in a laboratory-apartment may allow to detect changes in the use of language which may reflect EF difficulties linked to cognitive decline.

Adaptation and Reliability of the Cinderella Story Retell Task in Canadian French Persons Without Brain Injury

PURPOSE

Main concept (MC) analysis is a well-documented method of discourse analysis in adults with and without brain injury. This study aims to develop a MC checklist that is culturally and linguistically adapted for Canadian French speakers and examine its reliability. We also documented microstructural properties and provide a normative reference in persons not brain injured (PNBIs).

METHOD

Discourse samples from 43 PNBIs were collected. All participants completed the Cinderella story retell task twice. Manual transcription was performed for all samples. The 34 MCs for the Cinderella story retell task were adapted into Canadian French and used to score all transcripts. In addition, microstructural variables were extracted using Computerized Language Analysis (CLAN). Intraclass correlation coefficients were computed to assess interrater reliability for MC codes and microstructural variables. Test-retest reliability was assessed using intraclass correlations, Spearman's rho correlations, and the Wilcoxon signed-ranks test. Bland-Altman plots were used to examine the agreement of the discourse measures between the two sessions.

RESULTS

The MC checklist for the Cinderella story retell task adapted for Canadian French speakers is provided. Good-to-excellent interrater reliability was obtained for most MC codes; however, reliability ranged from poor to excellent for the "inaccurate and incomplete" code. Microstructural variables demonstrated excellent interrater reliability. Test-retest reliability ranged from poor to excellent for all variables, with the majority falling between moderate and excellent. Bland-Altman plots illustrated the limits of agreement between test and retest.

CONCLUSIONS

This study provides the MC checklist for clinicians and researchers working with Canadian French speakers when assessing discourse with the Cinderella story retell task. It also addresses the gap in available psychometric data regarding test-retest reliability in PNBIs.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24171087.

Treatment-induced neuroplasticity after anomia therapy in post-stroke aphasia: A systematic review of neuroimaging studies

We systematically reviewed the literature on neural changes following anomia treatment post-stroke. We conducted electronic searches of CINAHL, Cochrane Trials, Embase, Ovid MEDLINE, MEDLINE-in-Process and PsycINFO databases; two independent raters assessed all abstracts and full texts. Accepted studies reported original data on adults with post-stroke aphasia, who received behavioural treatment for anomia, and magnetic resonance brain imaging (MRI) pre- and post-treatment. Search results yielded 2481 citations; 33 studies were accepted. Most studies employed functional MRI and the quality of reporting neuroimaging methodology was variable, particularly for pre-processing steps and statistical analyses. The most methodologically robust data were synthesized, focusing on pre- versus post-treatment contrasts. Studies more commonly reported increases (versus decreases) in activation following naming therapy, primarily in the left supramarginal gyrus, and left/bilateral precunei. Our findings highlight the methodological heterogeneity across MRI studies, and the paucity of robust evidence demonstrating direct links between brain and behaviour in anomia rehabilitation.

The Three Terms Task - an open benchmark to compare human and artificial semantic representations

Word processing entails retrieval of a unitary yet multidimensional semantic representation (e.g., a lemon's colour, flavour, possible use) and has been investigated in both cognitive neuroscience and artificial intelligence. To enable the direct comparison of human and artificial semantic representations, and to support the use of natural language processing (NLP) for computational modelling of human understanding, a critical challenge is the development of benchmarks of appropriate size and complexity. Here we present a dataset probing semantic knowledge with a three-terms semantic associative task: which of two target words is more closely associated with a given anchor (e.g., is lemon closer to squeezer or sour?). The dataset includes both abstract and concrete nouns for a total of 10,107 triplets. For the 2,255 triplets with varying levels of agreement among NLP word embeddings, we additionally collected behavioural similarity judgments from 1,322 human raters. We hope that this openly available, large-scale dataset will be a useful benchmark for both computational and neuroscientific investigations of semantic knowledge.

The longitudinal trajectory of discourse from the hyperacute to the chronic phase in mild to moderate poststroke aphasia recovery: A case series study

BACKGROUND

Discourse analysis has recently received much attention in the aphasia literature. Even if post-stroke language recovery occurs throughout the longitudinal continuum of recovery, very few studies have documented discourse changes from the hyperacute to the chronic phases of recovery.

AIMS

To document a multilevel analysis of discourse changes from the hyperacute phase to the chronic phase of post-stroke recovery using a series of single cases study designs.

METHODS & PROCEDURES

Four people with mild to moderate post-stroke aphasia underwent four assessments (hyperacute: 0-24 h; acute: 24-72 h; subacute: 7-14 days; and chronic: 6-12 months post-onset). Three discourse tasks were performed at each time point: a picture description, a personal narrative and a story retelling. Multilevel changes in terms of macro- and microstructural aspects were analysed. The results of each discourse task were combined for each time point. Individual effect sizes were computed to evaluate the relative strength of changes in an early and a late recovery time frame.

OUTCOMES & RESULTS

Macrostructural results revealed improvements throughout the recovery continuum in terms of coherence and thematic efficiency. Also, the microstructural results demonstrated linguistic output improvement for three out of four participants. Namely, lexical diversity and the number of correct information units/min showed a greater gain in the early compared with the late recovery phase.

CONCLUSIONS & IMPLICATIONS

This study highlights the importance of investigating all discourse processing levels as the longitudinal changes in discourse operate differently at each phase of recovery. Overall results support future longitudinal discourse investigation in people with post-stroke aphasia.

WHAT THIS PAPER ADDS

What is already known on the subject Multi-level discourse analysis allows for in-depth analysis of underlying discourse processes. To date, very little is known on the longitudinal discourse changes from aphasia onset through to the chronic stage of recovery. This study documents multi-level discourse features in four people with mild to moderate aphasia in the hyperacute, acute, subacute and chronic stage of post-stroke aphasia recovery. What this paper adds to existing knowledge The study found that most discourse variables demonstrated improvement throughout time. Macrostructural variables of coherence and thematic units improved throughout the continuum whereas microstructural variables demonstrated greater gains in the early compared to the late period of recovery. What are the potential or actual clinical implications of this work? This study suggests that multilevel discourse analysis will allow a better understanding of post-stroke aphasia recovery, although more research is needed to determine the clinical utility of these findings. Future research may wish to investigate longitudinal discourse recovery in a larger sample of people with aphasia with heterogenous aphasia profiles and severities.

Validation of Videoconference Administration of Picture Description From the Western Aphasia Battery-Revised in Neurotypical Canadian French Speakers

PURPOSE

During the COVID-19 pandemic, clinicians and researchers have increasingly used remote online assessments to pursue their activities, but mostly with tests not validated for videoconference administration. This study aims to validate the remote online administration of picture description in Canadian French neurotypical speakers and to explore the thematic unit (TU) checklist recently developed.

METHOD

Spoken discourse elicited through the picture description task of the Western Aphasia Battery-Revised (WAB-R) was collected from Canadian French neurotypical speakers from Québec aged between 50 and 79 years old. Forty-seven participants completed the task in person, and 49 participants completed the task by videoconference. Videos of each discourse sample were transcribed using CHAT conventions. Microstructural variables were extracted using the CLAN (Computerized Language ANalysis) program, whereas thematic informativeness was scored for each sample using TUs. Chi-square tests were conducted to compare both groups on each TU; t tests were also performed on the total score of TUs and microstructural variables.

RESULTS

Groups were matched on sex, age, and education variables. The t tests revealed no intergroup difference for the total TU score and for the microstructural variables (e.g., mean length of utterances and number of words per minute). Chi-square tests showed no significant intergroup difference for all 16 TUs.

CONCLUSIONS

These findings support remote online assessment of the picnic scene of the WAB-R picture description in Canadian French neurotypical speakers. These results also validate the 16 TUs most consistently produced. The use of videoconference could promote and improve the recruitment of participants who are usually less accessible, such as people using assistive mobility technologies.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21476961.

Functional network and structural connections involved in picture naming

We mapped the left hemisphere cortical regions and fiber bundles involved in picture naming in adults by integrating task-based fMRI with dMRI tractography. We showed that a ventral pathway that "maps image and sound to meaning" involves the middle occipital, inferior temporal, superior temporal, inferior frontal gyri, and the temporal pole where a signal exchange is made possible by the inferior fronto-occipital, inferior longitudinal, middle longitudinal, uncinate fasciculi, and the extreme capsule. A dorsal pathway that "maps sound to speech" implicates the inferior temporal, superior temporal, inferior frontal, precentral gyri, and the supplementary motor area where the arcuate fasciculus and the frontal aslant ensure intercommunication. This study provides a neurocognitive model of picture naming and supports the hypothesis that the ventral indirect route passes through the temporal pole. This further supports the idea that the inferior and superior temporal gyri may play pivotal roles within the dual-stream framework of language.

A Standardized Set of 380 Pictures for Lebanese Arabic: Norms for Name Agreement, Conceptual Familiarity, Imageability, and Subjective Frequency

Research on language processing requires language-specific norms of pictorial and linguistic experimental stimuli across different psycholinguistic variables. Such normative data have not yet been collected for Lebanese Arabic (LA), an Arabic dialect. Arabic languages are characterized by diglossia: while modern standard Arabic is their common means of formal communication, Arabic dialects are the medium of oral communication within each community. This claims for specific dialectal norms. Thus, the main goal of the present study was to collect normative LA data for 380 pictures taken from Cykowicz, Friedman, Rothstein, and Snodgrass (The Quarterly Journal of Experimental Psychology Section A 50(3):560-585; including the 260 pictures of Snodgrass & Vanderwart in Journal of experimental psychology: Human learning and memory 6(2):174-215, 1980) using a sample of 248 native LA speakers. Norms are reported for name agreement, conceptual familiarity, imageability and subjective frequency, together with word length in number of letters and syllables. We compared the obtained norms with the normative data of other Arabic dialects (Levantine, Tunisian and Gulf Arabic) and with English, French and Spanish. Results showed the distinction of LA from the other Arabic dialects. This provides support of specific dialectal Arabic norms and will allow researchers to rigorously select the stimuli to investigate language processing in LA-speaking populations.

Picture Description of the Western Aphasia Battery Picnic Scene: Reference Data for the French Canadian Population

PURPOSE

The main aim of this study is to provide French Canadian reference data for quantitative measures extracted from connected speech samples elicited by the Western Aphasia Battery-Revised picnic scene, a discourse task frequently used in clinical assessment of acquired language disorders.

METHOD

Our sample consisted of 62 healthy French Canadian adults divided in two age groups: a 50- to 69-year-old group and a 70- to 90-year-old group.

RESULTS

High interrater reliability scores were obtained for most of the variables. Most connected speech variables did not demonstrate an age effect. However, the 70- to 90-year-old group produced more repetitions than the 50- to 69-year-old group and displayed reduced communication efficiency (number of information content units per minute).

CONCLUSION

These findings contribute to building a reference data set to analyze descriptive discourse production in clinical settings.

Comprehensive Analysis of Brain Volume in REM Sleep Behavior Disorder with Mild Cognitive Impairment

BACKGROUND

Rapid-eye-movement sleep behavior disorder (RBD) is a major risk factor for Parkinson's disease and dementia with Lewy bodies. More than a third of RBD patients have mild cognitive impairment (MCI), but their specific structural brain alterations remain poorly understood.

OBJECTIVE

This study aimed to investigate the local deformation and volume of gray and white matter tissue underlying MCI in RBD.

METHODS

Fifty-two idiopathic RBD patients, including 17 with MCI (33%), underwent polysomnography, neuropsychological, neurological, and magnetic resonance imaging assessments. MCI diagnosis was based on a subjective complaint, cognitive impairment on the neuropsychological battery, and preserved daily functioning. Forty-one controls were also included. Deformation-based morphometry (DBM), voxel-based morphometry (VBM), and regional volume analyses of the corpus callosum and basal forebrain cholinergic were performed. Multiple regressions models were also computed using anatomical, cognitive (composite z score), and motor parameters.

RESULTS

Globally, patients with MCI displayed a widespread pattern of local deformation and volume atrophy in the cortical (bilateral insula, cingulate cortex, precuneus, frontal and temporal regions, right angular gyrus, and mid-posterior segment of the corpus callosum) and subcortical (brainstem, corona radiata, basal ganglia, thalamus, amygdala, and right hippocampus) regions compared to patients without MCI (DBM) or controls (DBM and VBM). Moreover, brain deformation (DBM) in patients were associated with lower performance in attention and executive functions, visuospatial abilities, and higher motor symptoms severity.

CONCLUSION

The present study identified novel brain structural alterations in RBD patients with MCI which correlated with poorer cognitive performance. These results are consistent with those reported in patients with synucleinopathies-related cognitive impairment.

Predicting Early Post-stroke Aphasia Outcome From Initial Aphasia Severity

Background: The greatest degree of language recovery in post-stroke aphasia takes place within the first weeks. Aphasia severity and lesion measures have been shown to be good predictors of long-term outcomes. However, little is known about their implications in early spontaneous recovery. The present study sought to determine which factors better predict early language outcomes in individuals with post-stroke aphasia. Methods: Twenty individuals with post-stroke aphasia were assessed <72 h (acute) and 10-14 days (subacute) after stroke onset. We developed a composite score (CS) consisting of several linguistic sub-tests: repetition, oral comprehension and naming. Lesion volume, lesion load and diffusion measures [fractional anisotropy (FA) and axial diffusivity (AD)] from both arcuate fasciculi (AF) were also extracted using MRI scans performed at the same time points. A series of regression analyses were performed to predict the CS at the second assessment. Results: Among the diffusion measures, only FA from right AF was found to be a significant predictor of early subacute aphasia outcome. However, when combined in two hierarchical models with FA, age and either lesion load or lesion size, the initial aphasia severity was found to account for most of the variance (R 2 = 0.678), similarly to the complete models (R 2 = 0.703 and R 2 = 0.73, respectively). Conclusions: Initial aphasia severity was the best predictor of early post-stroke aphasia outcome, whereas lesion measures, though highly correlated, show less influence on the prediction model. We suggest that factors predicting early recovery may differ from those involved in long-term recovery.

Functional changes in the cortical semantic network in amnestic mild cognitive impairment

OBJECTIVE

Semantic memory impairment has been documented in individuals with amnestic Mild cognitive impairment (aMCI), who are at risk of developing Alzheimer's disease (AD), yet little is known about the neural basis of this breakdown. The aim of this study was to investigate the brain mechanisms associated with semantic performance in aMCI patients.

METHOD

A group of aMCI patients and a group of healthy controls carried out a semantic categorization task while their brain activity was recorded using magnetoencephalography (MEG). During the task, participants were shown famous faces and had to determine whether each famous person matched a given occupation. The main hypotheses were that (a) semantic processing should be compromised for aMCI patients, and (b) these deficits should be associated with cortical dysfunctions within specific areas of the semantic network.

RESULTS

Behavioral results showed that aMCI participants were significantly slower and less accurate than controls at the semantic task. Additionally, relative to controls, a significant pattern of hyperactivation was found in the aMCI group within specific regions of the extended semantic network, including the right anterior temporal lobe (ATL) and fusiform gyrus.

CONCLUSIONS

Abnormal functional activation within key areas of the semantic network suggests that it is compromised early in the disease process. Moreover, this pattern of right ATL and fusiform gyrus hyperactivation was positively associated with gray matter integrity in specific areas, but was not associated with any pattern of atrophy, suggesting that this pattern of hyperactivation may precede structural alteration of the semantic network in aMCI. (PsycINFO Database Record

Connected Speech Features from Picture Description in Alzheimer's Disease: A Systematic Review

The language changes that occur over the course of Alzheimer's disease (AD) can impact communication abilities and have profound functional consequences. Picture description tasks can be used to approximate everyday communication abilities of AD patients. As various methods and variables have been studied over the years, current knowledge about the most affected features of AD discourse in the context of picture descriptions is difficult to summarize. This systematic review aims to provide researchers with an overview of the most common areas of impairment in AD discourse as they appear in picture description tasks. Based on the 44 articles fulfilling inclusion criteria, our findings reflect a multidimensional pattern of changes in the production (speech rate), syntactic (length of utterance), lexical (word-frequency and use of pronouns), fluency (repetitions and word-finding difficulties), semantic (information units), and discourse (efficiency) domains. We discuss our findings in the light of current research and point to potential scientific and clinical uses of picture description tasks in the context of AD.

A MEG study of the neural substrates of semantic processing in semantic variant primary progressive aphasia

Despite a well-documented pattern of semantic impairment, the patterns of brain activation during semantic processing in semantic variant primary progressive aphasia (svPPA) still remain poorly understood. In the current study, one svPPA patient (EC) and six elderly controls carried out a general-level semantic categorization task while their brain activity was recorded using magnetoencephalography (MEG). Despite similar behavioral performance, EC showed hyperactivation of the left inferior temporal gyrus (ITG) and right anterior temporal lobe (ATL) relative to controls. This suggests that periatrophic regions within the ATL region may support preserved semantic abilities in svPPA.

Naming unique entities in the semantic variant of primary progressive aphasia and Alzheimer's disease: Towards a better understanding of the semantic impairment

While the semantic variant of primary progressive aphasia (svPPA) is characterized by a predominant semantic memory impairment, episodic memory impairments are the clinical hallmark of Alzheimer's disease (AD). However, AD patients also present with semantic deficits, which are more severe for semantically unique entities (e.g. a famous person) than for common concepts (e.g. a beaver). Previous studies in these patient populations have largely focused on famous-person naming. Therefore, we aimed to evaluate if these impairments also extend to other semantically unique entities such as famous places and famous logos. In this study, 13 AD patients, 9 svPPA patients, and 12 cognitively unimpaired elderly subjects (CTRL) were tested with a picture-naming test of non-unique entities (Boston Naming Test) and three experimental tests of semantically unique entities assessing naming of famous persons, places, and logos. Both clinical groups were overall more impaired at naming semantically unique entities than non-unique entities. Naming impairments in AD and svPPA extended to the other types of semantically unique entities, since a CTRL>AD>svPPA pattern was found on the performance of all naming tests. Naming famous places and famous persons appeared to be most impaired in svPPA, and both specific and general semantic knowledge for these entities were affected in these patients. Although AD patients were most significantly impaired on famous-person naming, only their specific semantic knowledge was impaired, while general knowledge was preserved. Post-hoc neuroimaging analyses also showed that famous-person naming impairments in AD correlated with atrophy in the temporo-parietal junction, a region functionally associated with lexical access. In line with previous studies, svPPA patients' impairment in both naming and semantic knowledge suggest a more profound semantic impairment, while naming impairments in AD may arise to a greater extent from impaired lexical access, even though semantic impairment for specific knowledge is also present. These results highlight the critical importance of developing and using a variety of semantically-unique-entity naming tests in neuropsychological assessments of patients with neurodegenerative diseases, which may unveil different patterns of lexical-semantic deficits.

Altered Gray Matter Structural Covariance Networks in Early Stages of Alzheimer's Disease

Clinical symptoms observed in Alzheimer's disease (AD) patients may reflect variations within specific large-scale brain networks, modeling AD as a disconnection syndrome. The present magnetic resonance imaging study aims to compare the organization of gray matter structural covariance networks between 109 cognitively unimpaired controls (CTRL) and 109 AD patients positive to beta-amyloid at the early stages of the disease, using voxel-based morphometry. The default-mode network (DMN; medial temporal lobe subsystem) was less extended in AD patients in comparison with CTRL, with a significant decrease in the structural association between the entorhinal cortex and the medial prefrontal and the dorsolateral prefrontal cortices. The DMN (midline core subsystem) was also less extended in AD patients. Trends toward increased structural association were observed in the salience and executive control networks. The observed changes suggest that early disruptions in structural association between heteromodal association cortices and the entorhinal cortex could contribute to an isolation of the hippocampal formation, potentially giving rise to the clinical hallmark of AD, progressive memory impairment. It also provides critical support to the hypothesis that the reduced connectivity within the DMN in early AD is accompanied by an enhancement of connectivity in the salience and executive control networks.

Longitudinal gray matter contraction in three variants of primary progressive aphasia: A tenser-based morphometry study

The present study investigated the pattern of longitudinal changes in cognition and anatomy in three variants of primary progressive aphasia (PPA). Eight patients with the non-fluent variant of PPA (nfvPPA), 13 patients with the semantic variant (svPPA), seven patients with the logopenic variant (lvPPA), and 29 age-matched, neurologically healthy controls were included in the study. All participants underwent longitudinal MRI, neuropsychological and language testing at baseline and at a 1-year follow-up. Tenser-based morphometry (TBM) was applied to T1-weighted MRI images in order to map the progression of gray and white matter atrophy over a 1-year period. Results showed that each patient group was characterized by a specific pattern of cognitive and anatomical changes. Specifically, nfvPPA patients showed gray matter atrophy progression in the left frontal and subcortical areas as well as a decline in motor speech and executive functions; svPPA patients presented atrophy progression in the medial and lateral temporal lobe and decline in semantic memory abilities; and lvPPA patients showed atrophy progression in lateral/posterior temporal and medial parietal regions with a decline in memory, sentence repetition and calculations. In addition, in all three variants, the white matter fibers underlying the abovementioned cortical areas underwent significant volume contraction over a 1-year period. Overall, these results indicate that the three PPA variants present distinct patterns of neuroanatomical contraction, which reflect their clinical and cognitive progression.

Proper name anomia in poststroke aphasics: evidence from a multiple-case study

We aimed to characterize difficulties in famous face naming in three poststroke aphasic patients with a lesion limited to the left mid-posterior temporal language regions, sparing the anterior temporal lobe. The patients did not present semantic deficits specific to known people. Nonetheless, they showed difficulties naming famous buildings in addition to famous faces, but they were comparable to healthy controls in generating proper names. Our results support the critical role of the mid-posterior temporal language regions in the lexical retrieval of proper names, namely from pictorial stimuli, in absence of semantic impairments.

Interhemispheric coupling improves the brain's ability to perform low cognitive demand tasks in Alzheimer's disease and high cognitive demand tasks in normal aging

OBJECTIVE

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects the corpus callosum (CC), which plays a key role in interhemispheric coupling in high-demand conditions. Using 3D callosal measurements and a letter-matching paradigm, this 2-part study investigated the neural substrate of interhemispheric coupling in individuals with AD or amnestic mild cognitive impairment (a-MCI) and age-matched healthy individuals (HC).

METHOD

Thirty-three right-handed participants were MRI scanned to measure the volume of the CC in 5 sections. In Study 1, AD, a-MCI, and HC individuals performed a low-demand perceptual letter shape-matching task (e.g., A-A); in Study 2, a-MCI and HC individuals performed a "case-sensitive" letter-matching task (Study 2A) and a "load-sensitive" letter-matching task (Study 2B).

RESULTS

The results showed a positive correlation between Response Times and the midbody of the CC at the lowest cognitive demand level (Study 1) in participants with AD, and the total CC, midbody, caudal body, and isthmus of the CC at high cognitive demand levels (Study 2A) in normal aging. The volume of the anterior part of the CC was significantly negatively correlated with the interhemispheric behavioral indices for the a-MCI group (Study 1 and Study 2B).

CONCLUSION

This study provides evidence that interhemispheric coupling may constitute a flexible mechanism that can improve the brain's ability to meet processing demands for low cognitive demand in AD and for high cognitive demand in normal aging.

Semantic dementia and persisting Wernicke's aphasia: linguistic and anatomical profiles

Few studies have directly compared the clinical and anatomical characteristics of patients with progressive aphasia to those of patients with aphasia caused by stroke. In the current study we examined fluent forms of aphasia in these two groups, specifically semantic dementia (SD) and persisting Wernicke's aphasia (WA) due to stroke. We compared 10 patients with SD to 10 age- and education-matched patients with WA in three language domains: language comprehension (single words and sentences), spontaneous speech and visual semantics. Neuroanatomical involvement was analyzed using disease-specific image analysis techniques: voxel-based morphometry (VBM) for patients with SD and overlays of lesion digitized lesion reconstructions in patients with WA. Patients with SD and WA were both impaired on tasks that involved visual semantics, but patients with SD were less impaired in spontaneous speech and sentence comprehension. The anatomical findings showed that different regions were most affected in the two disorders: the left anterior temporal lobe in SD and the left posterior middle temporal gyrus in chronic WA. This study highlights that the two syndromes classically associated with language comprehension deficits in aphasia due to stroke and neurodegenerative disease are clinically distinct, most likely due to distinct distributions of damage in the temporal lobe.

Single- and multiple-domain amnestic mild cognitive impairment: two sides of the same coin?

BACKGROUND

Amnestic mild cognitive impairment (aMCI) is considered a transition stage between normal aging and Alzheimer's disease (AD). Two main clinical subtypes of aMCI have been identified: (1) single-domain aMCI (aMCI-SD), with isolated episodic memory impairments, and (2) multiple-domain aMCI (aMCI-MD), with episodic memory impairments and deficits in one or more other cognitive domains.

AIMS

To map the pattern of gray matter (GM) atrophy associated with aMCI-SD, aMCI-MD and mild AD.

METHODS

A group of aMCI-SD, aMCI-MD characterized by executive function disorders, mild AD and cognitively unimpaired subjects underwent a comprehensive neuropsychological assessment and a high-definition MR brain scan. Voxel-based morphometry analysis was used to characterize the GM tissue loss in each patient group, and the common pattern of GM atrophy in aMCI-SD and aMCI-MD.

RESULTS

aMCI-SD and aMCI-MD are characterized by a common pattern of GM atrophy within the medial temporal cortex, predisposing to AD and correlating with the severity of verbal memory symptoms. Moreover, the pattern of GM atrophy observed in aMCI-SD, aMCI-MD and mild AD revealed that, from an anatomical point of view, these three clinical syndromes could represent three severity points along the continuum between normal aging and AD.

Reading disorders in primary progressive aphasia: a behavioral and neuroimaging study

Previous neuropsychological studies on acquired dyslexia revealed a double dissociation in reading impairments. Patients with phonological dyslexia have selective difficulty in reading pseudo-words, while those with surface dyslexia misread exception words. This double dissociation in reading abilities has often been reported in brain-damaged patients, but it has not been consistently shown in patients with neurodegenerative diseases. In this study, we investigated reading impairments and their anatomical correlates in various neurodegenerative diseases. First, we performed a behavioral analysis to characterize the reading of different word types in primary progressive aphasia (PPA). Then, we conducted a voxel-based morphometry neuroimaging study to map the brain areas in which gray matter volume correlated with the accurate reading of exception and pseudo-words. The results showed a differential pattern of exception and pseudo-word reading abilities in different clinical variants of PPA. Patients with semantic dementia, a disorder characterized by selective loss of semantic memory, revealed a pattern of surface dyslexia, while patients with logopenic/phonological progressive aphasia, defined by phonological loop deficits, showed phonological dyslexia. Neuroimaging results showed that exception word reading accuracy correlated with gray matter volume in the left anterior temporal structures, including the temporal pole, the anterior superior and middle temporal and fusiform gyri, while pseudo-word reading accuracy correlated with left temporoparietal regions, including the posterior superior and middle temporal and fusiform gyri, and the inferior parietal lobule. These results suggest that exception and pseudo-word reading not only rely upon different language mechanisms selectively damaged in PPA, but also that these processes are sustained by separate brain structures.

The logopenic/phonological variant of primary progressive aphasia

OBJECTIVE

Primary progressive aphasia (PPA) is characterized by isolated decline in language functions. Semantic dementia and progressive nonfluent aphasia are accepted PPA variants. A "logopenic" variant (LPA) has also been proposed, but its cognitive and anatomic profile is less defined. The aim of this study was to establish the cognitive and anatomic features of LPA.

METHODS

Six previously unreported LPA cases underwent extensive neuropsychological evaluation and an experimental study of phonological loop functions, including auditory and visual span tasks with digits, letters, and words. For each patient, a voxel-wise, automated analysis of MRI or SPECT data were conducted using SPM2.

RESULTS

In LPA, speech rate was slow, with long word-finding pauses. Grammar and articulation were preserved, although phonological paraphasias could be present. Repetition and comprehension were impaired for sentences but preserved for single words, and naming was moderately affected. Investigation of phonological loop functions showed that patients were severely impaired in digit, letter, and word span tasks. Performance did not improve with pointing, was influenced by word length, and did not show the normal phonological similarity effect. Atrophy or decreased blood flow was consistently found in the posterior portion of the left superior and middle temporal gyri and inferior parietal lobule.

CONCLUSIONS

Logopenic progressive aphasia (LPA) is a distinctive variant of primary progressive aphasia. Cognitive and neuroimaging data indicate that a deficit in phonological loop functions may be the core mechanism underlying the LPA clinical syndrome. Recent studies suggest that Alzheimer disease may be the most common pathology underlying the LPA clinical syndrome.

Evidence of white matter changes on diffusion tensor imaging in frontotemporal dementia

BACKGROUND

Two major clinical variants of frontotemporal dementia (FTD) have been described: frontal variant (fvFTD) and temporal variant (tvFTD).

OBJECTIVE

To analyze white matter (WM) and gray matter (GM) tissue organization in patients with fvFTD and tvFTD by means of diffusion tensor imaging and voxel-based morphometry, and the correlations with neuropsychological and behavioral variables.

DESIGN AND SETTING

Frontotemporal dementia clinic-based cohort and structural magnetic resonance imaging acquisition for voxel-based morphometry and diffusion tensor imaging measurements. Abnormalities were detected by a comparison with healthy control subjects. These variables were also correlated with clinical scores. Patients Thirty-six patients (28 with fvFTD and 8 with tvFTD) in early disease stage and 23 healthy controls who underwent standardized clinical and neuropsychological evaluation and magnetic resonance imaging.

INTERVENTIONS

Diffusion tensor imaging and voxel-based morphometry.

MAIN OUTCOME MEASURES

Neuroimaging analyses resulted in localized GM atrophy and reductions of white matter densities; the latter correlated with behavioral scores.

RESULTS

Voxel-based morphometry analysis showed separate patterns of GM atrophy in the 2 groups. Diffusion tensor imaging showed different WM reduction patterns in patients with fvFTD and tvFTD. The fvFTD group showed a selective WM reduction in the superior longitudinal fasciculus, interconnecting the frontal and occipital and the temporal and parietal regions. Conversely, patients with tvFTD were characterized by WM reductions in the inferior longitudinal fasciculus, which affected the connections between anterior temporal and frontal regions. The WM reductions in fvFTD paralleled both behavioral disturbances measured by Frontal Behavioral Inventory and neuropsychological deficits affecting frontal functions.

CONCLUSIONS

The fvFTD and tvFTD variants are associated not only with selective local GM reductions but also with significant WM damage in early disease phase. The different WM patterns contribute to the different clinical syndromes in FTD and could be responsible for the further progression of atrophy in the later disease stages.

The anatomy of category-specific object naming in neurodegenerative diseases

Neuropsychological studies suggest that knowledge about living and nonliving objects is processed in separate brain regions. However, lesion and functional neuroimaging studies have implicated different areas. To address this issue, we used voxel-based morphometry to correlate accuracy in naming line drawings of living and nonliving objects with gray matter volumes in 152 patients with various neurodegenerative diseases. The results showed a significant positive correlation between gray matter volumes in bilateral temporal cortices and total naming accuracy regardless of category. Naming scores for living stimuli correlated with gray matter volume in the medial portion of the right anterior temporal pole, whereas naming accuracy for familiarity-matched nonliving items correlated with the volume of the left posterior middle temporal gyrus. A previous behavioral study showed that the living stimuli used here also had in common the characteristic that they were defined by shared sensory semantic features, whereas items in the nonliving group were defined by their action-related semantic features. We propose that the anatomical segregation of living and nonliving categories is the result of their defining semantic features and the distinct neural subsystems used to process them.

Neuropsychological deficits and neural dysfunction in familial dyslexia

We report the neuropsychological profile and the pattern of brain activity during reading tasks in a sample of familial dyslexics. We studied our subjects with an in-depth neuropsychological assessment and with functional neuroimaging (fMRI) during word and pseudoword reading and false font string observations (baseline condition). The neuropsychological assessment revealed that familial dyslexia, in both persistent and compensated forms, is often associated with deficits in verbal short-term memory, phonological awareness and automatization abilities. The functional results showed a lack of activation in the posterior areas of the reading network. This study, together with the previously published VBM study (Brambati, S.M., Termine, C., Ruffino, M., Stella, G., Fazio, F., Cappa, S.F. and Perani, D., Regional reductions of gray matter volume in familial dyslexia, Neurology, 63 (2004) 742-5), provides a multiple modality evaluation of familial dyslexia. The neuropsychological assessment showed cognitive deficits associated with dyslexia that persist also in subjects with compensated reading deficit. Both the anatomical and the functional study point out a deficit in the posterior areas of the reading network.

Anatomical correlates of early mutism in progressive nonfluent aphasia

Patients with progressive nonfluent aphasia (PNFA) can become mute early in the course of the disease. Voxel-based morphometry showed that PNFA is associated with left anterior insula and inferior frontal atrophy. In PNFA with early mutism, volume loss was more prominent in the pars opercularis and extended into the left basal ganglia. Damage to the network of brain regions involved in both coordination and execution of speech causes mutism in PNFA.

Diffusion tensor imaging and voxel based morphometry study in early progressive supranuclear palsy

BACKGROUND

A comprehensive characterisation of grey and white matter changes in progressive supranuclear palsy (PSP), the second most common extrapyramidal syndrome after Parkinson disease, is still not available.

OBJECTIVE

To evaluate grey and white matter changes in mild PSP patients by voxel based morphometry (VBM) and diffusion tensor imaging (DTI), respectively.

METHODS

14 mild PSP patients and 14 healthy controls entered the study and underwent a clinical and neuropsychological evaluation according with a standardised assessment. Each subject had a structural magnetic resonance imaging (MRI) study. Processing analysis of MRI data was carried out according to optimised VBM and fractional anisotropy was determined.

RESULTS

Compared with the controls, in PSP patients VBM analysis showed a significant clusters of reduced grey matter in premotor cortex, frontal operculum, anterior insula, hippocampus, and parahippocampal gyrus, bilaterally. With regard to subcortical brain regions, the pulvinar, dorsomedial and anterior nuclei of the thalamus, and superior and inferior culliculum were affected bilaterally. A bilateral decrease in fractional anisotropy in superior longitudinal fasciculus, anterior part of corpus callosum, arcuate fascicolus, posterior thalamic radiations, and internal capsule, probably involving the cortico-bulbar tracts, was present in PSP patients.

CONCLUSIONS

These data provide evidence for both grey and white matter degeneration in PSP from the early disease stage. These structural changes suggest that atrophy of cortical and subcortical structures and neurodegeneration of specific fibre tracts contribute to neurological deficits in PSP.

Development of saccadic suppression in children

We measured saccadic suppression in adolescent children and young adults using spatially curtailed low spatial frequency stimuli. For both groups, sensitivity for color-modulated stimuli was unchanged during saccades. Sensitivity for luminance-modulated stimuli was greatly reduced during saccades in both groups but far more for adolescents than for young adults. Adults' suppression was on average a factor of about 3, whereas that for the adolescent group was closer to a factor of 10. The specificity of the suppression to luminance-modulated stimuli excludes generic explanations such as task difficulty and attention. We suggest that the enhanced suppression in adolescents results from the immaturity of the ocular-motor system at that age.

Regional reductions of gray matter volume in familial dyslexia

An in vivo anatomic study of gray matter volume was performed in a group of familial dyslexic individuals, using an optimized method of voxel-based morphometry. Focal abnormalities in gray matter volume were observed bilaterally in the planum temporale, inferior temporal cortex, and cerebellar nuclei, suggesting that the underlying anatomic abnormalities may be responsible for defective written language acquisition in these subjects.