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Individual differences in mental imagery are predicted by the intrinsic functional architecture of scene-selective regions
No full textMental imagery plays a crucial role in several cognitive processes, including navigation. It has been
found that cortical regions encoding navigationally-relevant information are also active during mental
imagery of navigational scenes. However, it remains unknown whether their activity reflects the
individuals’ ability to imagine a scene.
Here we used resting state functional connectivity based on functional magnetic resonance imaging
and self-reported questionnaires assessing the preference in using mental imagery (over linguistic)
representations to examine whether the pattern of reciprocal connections between scene-selective and
hippocampal regions reflected individual differences in mental imagery.
We found that the functional coupling between the left parahippocampal place area and the left
retrosplenial cortex significantly predicted the individual cognitive style, i.e., these regions were more
connected in people showing a preference in processing visual information about spatial attributes of
the scene versus verbal information. This suggests that the spontaneous brain activity in
navigationally relevant regions may account for individual differences in using spatial imagery
strategies
Individual Differences in Mental Imagery Modulates Effective Connectivity of Scene Regions at Rest
No full textSuccessful navigation relies on the human ability to identify, perceive and correctly process the spatial structure of a scene. It is well known that mental imagery plays a crucial role in navigation. Cortical regions encoding navigationally-relevant information are active during both perception and mental imagery of navigational scenes. The spatial navigational system relies on the activity of at least three visual cortical areas selectively responding to scenes: the Occipital Place Area (OPA) in the dorsal occipital lobe, the Retrosplenial Complex (RSC) within the parietal-occipital sulcus, and the Parahippocampal Place Area (PPA) at the boundary between the posterior parahippocampal cortex and the anterior lingual gyrus. Although functional connectivity between these regions has been studied, it remains unknown which is the causal influence of these regions on each other and whether their connectivity reflects the individuals’ ability to imagine a scene.
Forty-two healthy volunteers (mean age = 32.21, SD = 4.17, 24 female) underwent two fMRI sessions including two localizer scans for scene-selective regions and two resting-state scans. fMRI data were acquired on 3T Philips Allegra and Siemens Achieva scanner: for Allegra 242 (localizer scans) and 128 (rest scans) volumes, TR=2s, TE=30ms; for Achieva 249(localizer) and 160(resting-state) volumes, TR=1.9s, TE=25ms. The localizer fMRI experiment consisted of passive viewing of eight alternating blocks of face and place pictures presented for 300 ms every 500 ms, interleaved with a fixation period of 15 s on average. In the resting-state fMRI scans subjects lied at rest with eyes closed and no experimental task was imposed. The Vividness of Visual Imagery Questionnaire (VVIQ) (Marks, 1973 ) was administered to measure the vividness of visual imagery. Scene-responsive regions (PPA, RSC and OPA) were defined in each subject as the regions responding more strongly to places than to faces. Six head motion regressors, CSF, WM signal and discrete cosine transform were specified as regressors on resting-state General Linear Model.
Spectral Dynamic Causal models (DCM) for resting state fMRI (Friston et al., 2014) estimating intrinsic effective connectivity from observed BOLD responses were applied to regional time series computed as the principal eigenvariates of resting-state time series after standard preprocessing and removal of most typical confounds and artefact sources (Behzadi Y., 2007). Full-model DCMs were specified and inverted for each session separately. To estimate the average connectivity at the subject level we specified Parametric Empirical Bayes (PEB; Friston et al., 2016) modelling average connectivity (within subject) over sessions. Moreover, to define whether individual differences in mental imagery are predicted by the intrinsic connectivity between scene-selective regions, we performed a further PEB analysis with the VVIQ score as a covariate
Preferential signal pathways during the perception and the imagery of familiar places: a DCM study
No full textThe ability to perceive and remember relevant information about the space around us is necessary to correctly navigate in the environment. Perceiving and imagining visual stimuli, such as buildings and landscapes, activate similar content-dependent brain areas spanning from occipital to temporo-medial regions. However, how these areas interact with each other during perceptual stimulation and visual imagery of familiar scenes, especially when recollecting their spatial location, remains still unknown. In this study, we combined functional magnetic resonance imaging (fMRI) and resting-state functional connectivity (rs-fc) to assess the spontaneous fluctuation of signal among regions entailing scene-processing, the primary visual area (V1) and the hippocampus (HC), responsible for the retrieval of stored information. Afterward, we performed an effective connectivity analysis using Dynamic Causal Modelling (DCM) to evaluate whether the dynamic couplings among these regions differ between perception and imagery. The present study is based on a re-analysis of BOLD data from two datasets. The first one included fMRI resting-state data of 127 subjects, some of which (44 subjects) also underwent a functional localizer for scene-selective regions: the Parahippocampal Place Area (PPA), the Retrosplenial Complex (RSC) and the Occipital Place Area (OPA). The second dataset included data from 14 healthy subjects who participated in a study (Boccia et al., 2017), consisting of three scans of a scene perception-imagery experiment and two localizer scans for scene-selective regions. In the perception-imagery experiment, participants were asked to recall the spatial position of buildings within the University campus, in both perceptual and imagery trials. Specifically, pictures of the buildings were presented in the perceptual trials, whereas written labels were displayed on the screen in imagery trials. Firstly, we performed (rs-fc) analysis on the first fMRI dataset to study the functional connectivity profile at rest of scene selective regions, the primary visual area V1, and the hippocampus. Concurrently, we used the results of rs-fc analysis as constraints for studying the effective connectivity among the aforementioned regions using the Dynamic Causal Modelling (DCM) (Friston et al., 2003). Indeed, we applied DCM on BOLD data of the second dataset with the aim of inferring whether the neural communication among the beforehand regions differs during perception and imagery of familiar places. For each subject and region, we extracted the first eigenvariate of adjusted data. We specified and inverted a DCM with a full model among regions. Finally, we used Parametric Empirical Bayes (PEB) (Friston et al., 2016) analysis to estimate parameters at the group level. The whole-brain analysis revealed a consistent separation in two portions of the parahippocampal place area (PPA) – the anterior and the posterior PPA – in our sample. The rs- fc analysis revealed a connectivity pathway similar to the one observed in macaques and different preferential connectivity linking the anterior and the posterior PPA with the retrosplenial complex (RSC) and the occipital place area (OPA), respectively. Afterward, we performed an effective connectivity analysis using Dynamic Causal Modelling (DCM) to evaluate whether the dynamic couplings among these regions differ between perception and imagery. We found a strong and positive effect of the hippocampus on RSC during the retrieval of imagined landmark positions and a strong effect of occipital regions on both RSC and pPPA during the perception of familiar places
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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