Abstract Categorization is the mental operation by which the brain classifies objects and events. It is classically assessed using semantic and non-semantic matching or sorting tasks. These tasks show a high variability in performance across healthy controls and the cerebral bases supporting this variability remain unknown. In this study we performed a voxel-based morphometry study to explore the relationships between semantic and shape categorization tasks and brain morphometric differences in 50 controls. We found significant correlation between categorization performance and the volume of the grey matter in the right anterior middle and inferior temporal gyri. Semantic categorization tasks were associated with more rostral temporal regions than shape categorization tasks. A significant relationship was also shown between white matter volume in the right temporal lobe and performance in the semantic tasks. Tractography revealed that this white matter region involved several projection and association fibers, including the arcuate fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, and inferior longitudinal fasciculus. These results suggest that categorization abilities are supported by the anterior portion of the right temporal lobe and its interaction with other areas. Highlights Anterior temporal lobe morphometry correlates with categorization performances Semantic is associated with a more rostral temporal region than shape categorization Semantic categorization performances are associated with right temporal connections
Left unilateral neglect, a dramatic condition which impairs awareness of left-sided events, has been classically reported after right hemisphere cortical lesions involving the inferior parietal region. More recently, the involvement of long range white matter tracts has been highlighted, consistent with the idea that awareness of events occurring in space depends on the coordinated activity of anatomically distributed brain regions. Damage to the superior longitudinal fasciculus (SLF), linking parietal to frontal cortical regions, or to the inferior longitudinal fasciculus (ILF), connecting occipital and temporal lobes, has been described in neglect patients. In this study, four right-handed patients with right hemisphere strokes underwent a high definition anatomical MRI with diffusion tensor imaging (DTI) sequences and a pencil and paper neglect battery of tests. We used DTI tractography to visualise the SLF, ILF and the inferior fronto-occipital fasciculus (IFOF), a pathway running the depth of the temporal lobe, not hitherto associated with neglect. Two patients with cortical involvement of the inferior parietal and superior temporal regions, but intact and symmetrical fasciculi, showed no signs of neglect. The other two patients with signs of left neglect had superficial damage to the inferior parietal cortex and white matter damage involving the IFOF. These findings suggest that superficial damage to the inferior parietal cortex per se may not be sufficient to produce visual neglect. In some cases, a lesion to the direct connections between ventral occipital and frontal regions (ie, IFOF) may contribute to the manifestation of neglect by impairing the top down modulation of visual areas from the frontal cortex.
The study of the frontal connections is of particular interest for the neuroscience of aging. With aging the neuronal loss and small vessel alteration lead to progressive white matter damage associated with cognitive decline in the elderly (Pantoni, 2010). Cognitive decline affects predominantly executive functions, and brain changes seem to distribute unevenly, concerning predominantly the frontal region (Bishop et al., 2010). Previous studies using tract specific measurements revealed a slow decrease with aging in fractional anisotropy (FA) for frontal callosal tracts (Lebel et al., 2010) and for the average value of long tract connecting the frontal lobe (Jones et al., 2006) affecting more prominently the frontal portion of these tracts (Davis et al., 2009). Using voxel-based statistics, FA has been found to correlate negatively with aging, especially within the frontal lobes (Cabeza and Dennis, 2012). Whether this progressive decline affects the whole frontal white matter or specific tracts is unknown. Diffusion weighted datasets from 47 healthy volunteers aged 22-70 (M:F 24:23) were acquired on a 3T Siemens Verio TIM system equipped with a 32-channel head coil with the following parameters: voxel size 2x2x2 mm, matrix 128x128, slices 60, NEX 1, TE 90 ms, b-value 1500 s/mm2, 60 diffusion-weighted directions and 6 non-diffusion-weighted volumes, using a spin-echo EPI sequence. Cardiac Gating was applied with effective TR of 24 R-R intervals. Diffusion datasets were corrected for motion and eddy current distortions (Smith et al., 2004) and then processed with a Spherical Deconvolution algorithm based on a damped version of the Richardson-Lucy algorithm (Dell'acqua et al., 2010, Dell'Acqua et al., 2013). Tractography was performed following the method described in (Catani et al., 2012). We dissected fifty-five frontal tracts including U-shaped fibers. For each dissection FA (Basser and Pierpaoli, 1996) and hindrance modulated oriented anisotropy (HMOA) (Dell'Acqua et al., 2013) were extracted as an indirect measure of the tract integrity and correlated with the age of the participants regressing out the level of education. P values are presented after false discovery rate (FDR) correction for multiple comparisons (* p < 0.05 ; ** p < 0.01 ; *** p < 0.001). Aging was significantly associated with a decrease of FA (r = - 0.501*) and OA (r = - 0.508**) in the frontal projections of the corpus callosum. Aging was also associated with a decrease of OA in the right frontal lobe including the SLF I (r = - 0.401**) and SLF III (r = - 0.576***) branches of the superior longitudinal fasciculus, inferior fronto-occipital fasciculus (r = - 0.331*), fronto-thalamic projections (r = - 0.515***). In the left hemisphere, OA measure also decreased with aging for the frontal inferior longitudinal fasciculus (r = - 0.542***) and the frontal orbito-polar tract (r = - 0.542***). Results are summarized in Figure 1. We confirmed preliminary evidences reporting reduced integrity in the frontal portion of the corpus callosum associated with aging (Lebel et al., 2010). This commissural decline may explain the increased reaction times associated with aging reported in tasks requiring interhemispheric transfer (Reuter-Lorenz and Stanczak, 2000). Our results also suggest for the first time that aging alters significantly other tracts in the right hemisphere which brings up interesting pathophysiological hypotheses for ageing decline in visuospatial and verbal working memory, memory encoding and retrieval, reward-based associative learning that can be tested in the elderly (Cabeza and Dennis, 2012). Correlation between age of the participants and tract specific measurements, a) frontal corpus callosum b) first branch of the right superior longitudinal fasciculus; c) third branch of the right superior longitudinal fasciculus; d) right inferior fronto-occipital fasciculus; e) right fronto-thalamic projections; f) left frontal orbito-polar tract; g) left frontal inferior longitudinal fasciculus. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001 false discovery rate corrected for multiple comparison.
SEE BURGESS DOI101093/BRAIN/AWW092 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE : Analogical reasoning is at the core of the generalization and abstraction processes that enable concept formation and creativity. The impact of neurological diseases on analogical reasoning is poorly known, despite its importance in everyday life and in society. Neuroimaging studies of healthy subjects and the few studies that have been performed on patients have highlighted the importance of the prefrontal cortex in analogical reasoning. However, the critical cerebral bases for analogical reasoning deficits remain elusive. In the current study, we examined analogical reasoning abilities in 27 patients with focal damage in the frontal lobes and performed voxel-based lesion-behaviour mapping and tractography analyses to investigate the structures critical for analogical reasoning. The findings revealed that damage to the left rostrolateral prefrontal region (or some of its long-range connections) specifically impaired the ability to reason by analogies. A short version of the analogy task predicted the existence of a left rostrolateral prefrontal lesion with good accuracy. Experimental manipulations of the analogy tasks suggested that this region plays a role in relational matching or integration. The current lesion approach demonstrated that the left rostrolateral prefrontal region is a critical node in the analogy network. Our results also suggested that analogy tasks should be translated to clinical practice to refine the neuropsychological assessment of patients with frontal lobe lesions.
Creativity is of central importance for human civilization, yet its neurocognitive bases are poorly understood. The aim of the present study was to integrate existing functional imaging data by using the meta-analysis approach. We reviewed 34 functional imaging studies that reported activation foci during tasks assumed to engage creative thinking in healthy adults. A coordinate-based meta-analysis using Activation Likelihood Estimation (ALE) first showed a set of predominantly left-hemispheric regions shared by the various creativity tasks examined. These regions included the caudal lateral prefrontal cortex (PFC), the medial and lateral rostral PFC, and the inferior parietal and posterior temporal cortices. Further analyses showed that tasks involving the combination of remote information (combination tasks) activated more anterior areas of the lateral PFC than tasks involving the free generation of unusual responses (unusual generation tasks), although both types of tasks shared caudal prefrontal areas. In addition, verbal and non-verbal tasks involved the same regions in the left caudal prefrontal, temporal, and parietal areas, but also distinct domain-oriented areas. Taken together, these findings suggest that several frontal and parieto-temporal regions may support cognitive processes shared by diverse creativity tasks, and that some regions may be specialized for distinct types of processes. In particular, the lateral PFC appeared to be organized along a rostro-caudal axis, with rostral regions involved in combining ideas creatively and more posterior regions involved in freely generating novel ideas.
Introduction: The COVID-19 pandemic can certainly be considered a turning point in history. In 2021 vaccines have finally arrived. They were met with different attitudes from people, from a willingness to be vaccinated as soon as possible to hostility. This study aimed to conduct a survey assessing public beliefs and attitudes towards vaccinations and COVID-19. Material and methods: A survey was conducted online from January 13 to February 14, 2022. It was completed by 7025 adult participants. After screening for potential fraudulent responses, 7018 valid responses were included in the analysis. Results: Among the concerns about vaccination, the most common reason for hesitation was the lack of information on long-term side effects, cited by 41.4% of the vaccinated. Doubts about vaccine effectiveness were reported by 15.9% of people, and fear of severe side effects was mentioned by 32.2%. For the unvaccinated, the most common affirmative response was the desire for a COVID passport, which 43.7% of individuals supported. Concerns about avoiding severe illness led 38.7% to hesitate, while 25.1% felt social pressure. Among the statements about vaccinations and COVID-19, unvaccinated individuals most commonly believe in the falsification of pandemic statistics, think that the time from vaccine development to deployment was too short, and fear that vaccines might cause serious side effects. In contrast, vaccinated individuals are more likely to believe in the severity of the disease and the effectiveness of vaccines. Conclusions: The present findings indicate the need for increased focus on vaccine education. It is crucial to inform the public about where to access credible and verified information. Additionally, it is important to approach rumors and theories circulating on social media with skepticism. Developing and distributing educational materials, such as pamphlets and online resources, can help ensure the public has access to reliable health information.
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