343 research outputs found
Visual and auditory perceptual strength norms for 3,596 French nouns and their relationship with other psycholinguistic variables
Perceptual experience plays a critical role in the conceptual representation of words. Higher levels of semantic variables such as imageability, concreteness, and sensory experience are generally associated with faster and more accurate word processing. Nevertheless, these variables tend to be assessed mostly on the basis of visual experience. This underestimates the potential contributions of other perceptual modalities. Accordingly, recent evidence has stressed the importance of providing modality-specific perceptual strength norms. In the present study, we developed French Canadian norms of visual and auditory perceptual strength (i.e., the modalities that have major impact on word processing) for 3,596 nouns. We then explored the relationship between these newly developed variables and other lexical, orthographic, and semantic variables. Finally, we demonstrated the contributions of visual and auditory perceptual strength ratings to visual word processing beyond those of other semantic variables related to perceptual experience (e.g., concreteness, imageability, and sensory experience ratings). The ratings developed in this study are a meaningful contribution toward the implementation of new studies that will shed further light on the interaction between linguistic, semantic, and perceptual systems
Differential involvement of the anterior temporal lobes in famous people semantics
The ability to recognize a famous person occurs through semantic memory. Previous
neuroimaging studies have shown that the anterior temporal lobes (ATLs) are involved
in the recognition of famous people. However, it is still a matter of debate whether
the semantic processing of names or pictures of famous people has an impact on
the activation of ATLs. The aim of this study was to explore the pattern of activation
associated with a semantic processing of famous people based on face and written name
stimuli. Fifteen healthy young individuals participated in our fMRI study, in which they
were asked to perform a semantic categorization judgment task, based on profession, of
visually presented pictures, and names of famous people. Neuroimaging findings showed
a common pattern of activation for faces and names mainly involving the inferior frontal
regions, the posterior temporal lobe, the visual cortex, and the ATLs. We found that
the comparison names vs. pictures lead to significant activation in the anterior superior
temporal gyrus. On the other hand, faces vs. names seemed associated with increased
activation in the medial ATL. Moreover, our results demonstrated that the functional
connectivity network anchored to the medial ATL, compared to the anterior STG, is more
connected to the bilateral occipital lobe and fusiform gyrus that are regions implicated in
the visual system and visual processing of faces. This study provides critical evidence of
the differential involvement of ATL regions in semantics of famous people
Comprehension of concrete and abstract words in semantic variant primary progressive aphasia and Alzheimer’s disease: a behavioral and neuroimaging study
The aim of this study was to investigate the comprehension of concrete, abstract and abstract emotional words in semantic variant primary progressive aphasia (svPPA), Alzheimer’s disease (AD), and healthy elderly adults (HE) Three groups of participants (9 svPPA, 12 AD, 11 HE) underwent a general neuropsychological assessment, a similarity judgment task, and structural brain MRI. The three types of words were processed similarly in the group of AD participants. In contrast, patients in the svPPA group were significantly more impaired at processing concrete words than abstract words, while comprehension of abstract emotional words was in between. VBM analyses showed that comprehension of concrete words relative to abstract words was significantly correlated with atrophy in the left anterior temporal lobe. These results support the view that concrete words are disproportionately impaired in svPPA, and that concrete and abstract words may rely upon partly dissociable brain regions
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
The role of the left anterior temporal lobe for unpredictable and complex mappings in word reading
The anterior temporal lobes (ATLs) have been consistently associated with semantic
processing which, in turn, has a key role in reading aloud single words. This study aimed
to investigate (1) the reading abilities in patients with the semantic variant of primary
progressive aphasia (svPPA), and (2) the relationship between gray matter (GM) volume
of the left ATL and word reading performance using voxel-based morphometry (VBM).
Three groups of participants (svPPA, Alzheimer’s Disease, AD and healthy elderly adults)
performed a reading task with exception words, regular words and pseudowords, along
with a structural magnetic resonance imaging scan. For exception words, the svPPA
group had a lower accuracy and a greater number of regularization errors as compared
to the control groups of healthy participants and AD patients. Similarly, for regular words,
svPPA patients had a lower accuracy in comparison with AD patients, and a greater
number of errors related to complex orthography-to-phonology mappings (OPM) in
comparison to both control groups. VBM analyses revealed that GM volume of the left
ATL was associated with the number of regularization errors. Also, GM volume of the left
lateral ATL was associated with the number of errors with complex OPM during regular
word reading. Our results suggest that the left ATL might play a role in the reading of
exception words, in accordance with its role in semantic processing. Results further
support the involvement of the left lateral ATL in combinatorial processes, including the
integration of semantic and phonological information, for both exception and regular
words
Recommended from our members
Deformation-based shape analysis of the hippocampus in the semantic variant of primary progressive aphasia and Alzheimer’s disease
Background
Increasing evidence shows that the semantic variant of primary progressive aphasia (svPPA) is characterized by hippocampal atrophy. However, less is known about disease-related morphological hippocampal changes. The goal of the present study is to conduct a detailed characterization of the impact of svPPA on global hippocampus volume and morphology compared with control subjects and patients with Alzheimer’s disease (AD).
Methods
We measured hippocampal volume and deformation-based shape differences in 22 patients with svPPA compared with 99 patients with AD and 92 controls. Multiple Automatically Generated Templates Brain Segmentation Algorithm (MAGeT-Brain) was used on MRI images obtained at the diagnostic visit.
Results
Comparable left and right hippocampal atrophy were observed in svPPA and AD. Deformation-based shape analysis showed a common pattern of morphological deformation in svPPA and AD compared with controls. More specifically, both svPPA and AD showed inward deformations in the dorsal surface of the hippocampus, from head to tail on the left side, and more limited to the anterior portion of the body in the right hemisphere. These results also pointed out that both diseases are characterized by a lateral displacement of the central part (body) of the hippocampus.
Discussion
Our study provides critical new evidence of hippocampal morphological changes in svPPA, similar to those found in AD. These findings highlight the importance of considering morphological hippocampal changes as part of the anatomical profile of patients with svPPA
Dormant origins and fork protection mechanisms rescue sister forks arrested by transcription
The yeast RNA/DNA helicase Sen1, Senataxin in human, preserves the integrity of replication forks encountering transcription by removing RNA-DNA hybrids. Here we show that, in sen1 mutants, when a replication fork clashes head-on with transcription is arrested and, as a consequence, the progression of the sister fork moving in the opposite direction within the same replicon is also impaired. Therefore, sister forks remain coupled when one of the two forks is arrested by transcription, a fate different from that experienced by forks encountering Double Strand Breaks. We also show that dormant origins of replication are activated to ensure DNA synthesis in the proximity to the forks arrested by transcription. Dormant origin firing is not inhibited by the replication checkpoint, rather dormant origins are fired if they cannot be timely inactivated by passive replication. In sen1 mutants, the Mre11 and Mrc1-Ctf4 complexes protect the forks arrested by transcription from processing mediated by the Exo1 nuclease. Thus, a harmless head-on replication-transcription clash resolution requires the fine-tuning of origin firing and coordination among Sen1, Exo1, Mre11 and Mrc1-Ctf4 complexes
La sémantique, la lecture de mots irréguliers et les lobes temporaux antérieurs
Dans cette recension des écrits nous présentons les résultats d’études comportementales
et de neuroimagerie mettant en rapport la sémantique et la lecture de mots irréguliers,
ainsi que la sémantique et les lobes temporaux antérieurs (LTA). Plus particulièrement,
nous nous concentrons sur l’atteinte de la lecture à voix haute de mots irréguliers, soit la
dyslexie de surface, chez la variante sémantique de l’Aphasie Primaire Progressive
(vsAPP). Cette maladie neurodégénérative débute par l’atrophie des lobes temporaux
antérieurs et touche d’abord la mémoire sémantique. À partir des études
comportementales, il est possible de conclure que la dyslexie de surface est très souvent
observée chez des patients atteints de vsAPP. Ceci semble mettre en avant le rapport
entre la dyslexie de surface et la dégradation de la mémoire sémantique chez ce type de
patients. De plus, la nature neurodégénérative de la vsAPP a permis d’établir le rapport
entre l’atteinte sémantique et les LTA. Les études de neuroimagerie menées auprès des
participants sains ont aussi mis en évidence le rôle des LTA lors du traitement
sémantique et lors de la lecture de mots irréguliers. Le rôle des LTA en lecture de mots
irréguliers semblerait être celui de la sémantique, plutôt que celui de la lecture ellemême.
En somme, les modèles théoriques et computationnels qui postulent l’activation
sémantique pour la lecture de mots irréguliers permettraient d’expliquer le profil de
lecture et l’atteinte sémantique trouvés en vsAPP, ainsi que le réseau de lecture de mots
irréguliers qui inclut le LTA gauche.This review presents the results of behavioural and neuroimaging studies that address the
relationship between semantics, irregular word reading and the anterior temporal lobes
(ATLs). In particular we focused on acquired surface dyslexia, i.e., irregular word
reading impairment , in patients suffering from the semantic variant of primary
progressive aphasia (svPPA). svPPA is a neurodegenerative disease that occurs following
the atrophy of the ATLs. This disease is early characterized by semantic memory
impairments. Taken together, behavioural studies show that svPPA patients often suffer
from acquired surface dyslexia. This pattern highlights the relationship between acquired
surface dyslexia and semantic knowledge degradation in svPPA. Moreover, the
neurodegenerative nature of svPPA has pointed out to the relationship between semantic
impairment and the ATLs. Neuroimaging studies in healthy participants have also
provided evidence of the role of the ATLs in semantic processing and irregular word
reading. The ATLs seem to be related to semantic processing in irregular word reading,
more than to irregular word reading itself. In sum, the results of the studies reviewed here
provide evidence for theoretical and computational models that predict semantic
activation during irregular word reading. This semantic contribution can explain the
profile of surface dyslexia in svPPA, as well as the brain network that sustains the
processing of this type of words and that includes the left ATL
Recommended from our members
Comparison of Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Thickness Values Using Spectral-Domain and Swept-Source OCT
PURPOSE: To compare peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thickness measurements obtained with spectral domain optical coherence tomography (SD-OCT) and swept-source OCT (SS-OCT) using an OCT-angiography scanning protocol, and their ability to distinguish among patients with glaucoma, glaucoma suspects (GS), and healthy controls (HC).
METHODS: Cross-sectional study of 196 eyes (81 glaucoma, 48 GS, and 67 HC) of 119 participants. Participants underwent peripapillary and macular OCT with SD-OCT and SS-OCT. Parameters of interest were average and sector-wise pRNFL and mGCIPL thickness. Inter-device agreement was investigated with Bland-Altman statistics. Conversion formulas were developed with linear regression. Diagnostic performances were evaluated with area under the receiver operating characteristic curves.
RESULTS: Both SD-OCT and SS-OCT detected a significant pRNFL and mGCIPL thinning in glaucoma patients compared to HC and GS for almost all study sectors. A strong linear relationship between the two devices was present for all quadrants/sectors (R2 ≥ 0.81, P < 0.001), except for the nasal (R2 = 0.49, P < 0.001) and temporal (R2 = 0.62, P < 0.001) pRNFL quadrants. SD-OCT and SS-OCT measurements had a proportional bias, which could be removed with conversion formulas. Overall, the two devices showed similar diagnostic abilities.
CONCLUSIONS: Thickness values obtained with SD-OCT and SS-OCT are not directly interchangeable but potentially interconvertible. Both devices have a similar ability to discriminate glaucoma patients from GS and healthy subjects.
TRANSLATIONAL RELEVANCE: OCT-Angiography scans can be reliably used to obtain structural metrics in glaucoma patients
Flood Protection in Venice under Conditions of Sea-Level Rise: An Analysis of Institutional and Technical Measures
It is widely acknowledged that in times of climate change loss of coastal resources and risk for human life can be minimized by implementing adaptation strategies. Such strategies need to encompass a balanced mix of non-structural (institutional) and structural (technical) measures based on sound scientific knowledge. This article discusses measures carried out to protect the city of Venice, Italy from flooding (locally known as “high water”), and reflects on their ability to anticipate a possible acceleration of sea-level rise as induced by climate change. It is based on scientific literature, legislative and policy documents of key institutions, reports and documents of organizations working on Venice issues, newspaper articles, and interviews. Our analysis shows that the synergic action of the hydraulic defense infrastructure under construction is in principle adequate to withstand a broad range of sea-level rise scenarios for the next 100 years. However, when the goal is to use these investments effectively major changes in the existing institutional arrangements will be required in the years to come. The Venice findings point out the difficulties and yet the importance of identifying and implementing both non-structural and structural measures to adapt to climate change
- …