Previous work has shown that the meaning of a quantifier such as “many” or “few” depends in part on quantity. However, the meaning of a quantifier may vary depending on the context, e.g. in the case ...of common entities such as “many ants” (perhaps several thousands) compared to endangered species such as “many pandas” (perhaps a dozen). In a recent study (Heim et al., 2015 Front. Psychol.) we demonstrated that the relative meaning of “many” and “few” may be changed experimentally. In a truth value judgment task, displays with 40% of circles in a named color initially had a low probability of being labeled “many”. After a training phase, the likelihood of acceptance 40% as “many” increased. Moreover, the semantic learning effect also generalized to the related quantifier “few” which had not been mentioned in the training phase. Thus, fewer 40% arrays were considered “few.” In the present study, we tested the hypothesis that this semantic adaptation effect was supported by cytoarchitectonic Brodmann area (BA) 45 in Broca's region which may contribute to semantic evaluation in the context of language and quantification. In an event-related fMRI study, 17 healthy volunteers performed the same paradigm as in the previous behavioral study. We found a relative signal increase when comparing the critical, trained proportion to untrained proportions. This specific effect was found in left BA 45 for the trained quantifier “many”, and in left BA 44 for both quantifiers, reflecting the semantic adjustment for the untrained but related quantifier “few.” These findings demonstrate the neural basis for processing the flexible meaning of a quantifier, and illustrate the neuroanatomical structures that contribute to variable meanings that can be associated with a word when used in different contexts.
•The meaning of quantifiers (e.g. “many”) can be changed.•This change translates to other quantifiers.•Left BA45 is crucial for the re-interpretation of quantifier semantics.
The most widely established diagnostic criteria for the behavioral variant of frontotemporal dementia have now been in use for almost a decade. Although consensus criteria have provided a much needed ...standard for frontotemporal dementia research, a growing body of evidence suggests that revisions are needed to improve their applicability. In this article, we discuss the limitations of current diagnostic criteria and propose the establishment of an international consortium to revise diagnostic and research criteria for the behavioral variant of frontotemporal dementia.
Knowledge of the neural basis for language and related aspects of cognition has been advanced through detailed studies of patients with primary progressive aphasia. This brief review highlights some ...recent work.
The impairment of semantic knowledge in patients with semantic dementia appears to influence performance in a wide variety of linguistic and cognitive domains, including morphological agreements such as the irregular past tense. Computational studies modeling the deficits of these patients have advanced interpretations of the impairments in semantic dementia. Imaging analyses have confirmed the presence of temporal atrophy cross-sectionally and longitudinally in these patients. In patients with semantic dementia, it appears that both the left temporal and right temporal regions contribute in different proportions to naming and comprehension, although the nature of the process underlying the consolidation of knowledge in semantic memory continues to be actively debated. In patients with progressive non-fluent aphasia, recent work has emphasized an impairment with verbs. Functional neuroimaging work with progressive non-fluent aphasics, compared directly to non-aphasic patients with frontotemporal dementia, has demonstrated a dissociation for grammatical and working memory aspects of sentence processing within the left frontal cortex.
These findings will improve diagnostic accuracy, prognostic ability, and therapeutic potential in patients with progressive aphasia.
Amyotrophic lateral sclerosis (ALS) and the behavioural variant of frontotemporal dementia (bvFTD) commonly share the presence of TDP-43 inclusions. Structural MRI studies demonstrated evidence for ...TDP-43 pathology spread, but while structural imaging usually reveals overt neuronal loss, perfusion imaging may detect more subtle neural activity alterations. We evaluated perfusion as an early marker for incipient pathology associated brain alterations in TDP-43 proteinopathies. Cortical thickness (CT) and perfusion measurements were obtained in ALS (N=18), pathologically and/or genetically confirmed bvFTD-TDP (N=12), and healthy controls (N=33).
BvFTD showed reduced frontotemporal CT, hypoperfusion encompassing orbitofrontal and temporal cortices, and hyperperfusion in motor and occipital regions. ALS did not show reduced CT, but exhibited hypoperfusion in motor and temporal regions, and hyperperfusion in frontal and occipital cortices. Frontotemporal hypoperfusion and reduced CT correlated with cognitive and behavioural impairment as investigated using Mini Mental State Examination (MMSE) and Philadelphia Brief Assessment of Cognition (PBAC) in bvFTD, and hypoperfusion in motor regions correlated with motor disability as measured by the ALS Functional Rating Scale-Revised (ALSFRS-R) in ALS.
Hypoperfusion marked early pathologically involved regions, while hyperperfusion characterized regions of late pathological involvement. Distinct perfusion patterns may provide early markers of pathology distribution in TDP-43 proteinopathies.
To evaluate whether occupational attainment influences the trajectory of longitudinal cognitive decline in behavioral variant frontotemporal degeneration (bvFTD). Single-center, retrospective, ...longitudinal study. Sixty-three patients meeting consensus criteria for bvFTD underwent evaluation at the University of Pennsylvania Frontotemporal Degeneration Center. All patients were studied longitudinally on letter-guided fluency, category-naming fluency and Boston Naming Test (BNT). Occupational attainment was defined categorically by assigning each individual’s occupation to a professional or non-professional category. Linear mixed-effects models evaluated the interaction of neuropsychological performance change with occupational status. Regression analyses were used to relate longitudinal decline in executive function to baseline MRI grey matter atrophy. Higher occupational status was associated with a more severe slope of cognitive decline on letter-guided fluency and category-naming fluency, but not BNT. Faster rates of longitudinal decline on letter-guided and category-naming fluency were associated with more severe baseline grey matter atrophy in right dorsolateral and inferior frontal regions. Our longitudinal findings suggest that bvFTD individuals with higher lifetime cognitive experience demonstrate more rapid decline on measures of executive function. This finding converges with cross-sectional evidence suggesting that lifetime cognitive experiences contribute to heterogeneity in clinical progression in bvFTD.
For spectral‐domain optical coherence tomography (SD‐OCT) studies of neurodegeneration, it is important to understand how segmentation algorithms differ in retinal layer thickness measurements, ...segmentation error locations and the impact of manual correction. Using macular SD‐OCT images of frontotemporal degeneration patients and controls, we compare the individual and aggregate retinal layer thickness measurements provided by two commonly used algorithms, the Iowa Reference Algorithm and Heidelberg Spectralis, with manual correction of significant segmentation errors. We demonstrate small differences of most retinal layer thickness measurements between these algorithms. Outer sectors of the Early Treatment Diabetic Retinopathy Study grid require a greater percent of eyes to be corrected than inner sectors of the retinal nerve fiber layer (RNFL). Manual corrections affect thickness measurements mildly, resulting in at most a 5% change in RNFL thickness. Our findings can inform researchers how to best use different segmentation algorithms when comparing retinal layer thicknesses.
The purpose of this study is to compare two commonly used spectral‐domain optical coherence tomography segmentation algorithms regarding retinal layer thickness measurements and impact of manual correction in frontotemporal degeneration patients and controls. This study finds that these algorithms provide small differences in retinal layer thicknesses. Manual correction mildly affects thickness measurements and segmentation errors are more common for the outer sectors of the Early Treatment Diabetic Retinopathy Study grid.
Patients with semantic dementia (SD) have a striking impairment in semantic memory, but the basis for this deficit is unclear. We examined semantic memory for concrete and abstract verbs with a ...two-alternative, forced-choice measure of lexical semantic associative knowledge. Patients with SD had significantly greater difficulty with concrete verbs (z = -3.33) than with abstract verbs (z = -2.05), a "reversal of the concreteness effect" that was present in a majority of individual patients. The subgroup of SD patients with imaging had significant cortical thinning in the anterior and inferolateral portions of the temporal lobes. These areas of visual association cortex may be important for storing and processing visual features for word meaning. Moreover, poor performance with concrete relative to abstract verbs correlated with cortical thinning of the right anterior temporal lobe in SD, suggesting that this region may contribute to storing and processing visual semantic features. These observations raise the possibility that degraded visual feature knowledge contributes in part to the impaired comprehension of concrete words in SD.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
