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Hypnotic susceptibility modulates brain activity related to experimental placebo analgesia
No full textIdentifying personality traits and neural signatures that predict placebo responsiveness is important, both on theoretical and practical grounds. In the present functional magnetic resonance imaging (fMRI) study, we performed multiple-regression interaction analysis to investigate whether hypnotic susceptibility (HS), a cognitive trait referring to the responsiveness to suggestions, explains interindividual differences in the neural mechanisms related to conditioned placebo analgesia in healthy volunteers. HS was not related to the overall strength of placebo analgesia. However, we found several HS-related differences in the patterns of fMRI activity and seed-based functional connectivity that accompanied placebo analgesia. Specifically, in subjects with higher HS, the placebo response was related to increased anticipatory activity in a right dorsolateral prefrontal cortex focus, and to reduced functional connectivity of that focus with brain regions related to emotional and evaluative pain processing (anterior mid-cingulate cortex/medial prefrontal cortex); an opposite pattern of fMRI activity and functional connectivity was found in subjects with lower HS. During pain perception, activity in the regions reflecting attention/arousal (bilateral anterior thalamus/left caudate) and self-related processing (left precuneus and bilateral posterior temporal foci) was negatively related to the strength of the analgesic placebo response in subjects with higher HS, but not in subjects with lower HS. These findings highlight HS influences on brain circuits related to the placebo analgesic effects. More generally, they demonstrate that different neural mechanisms can be involved in placebo responsiveness, depending on individual cognitive traits
Alterations in cortical gray matter volume, thickness and surface area in women with fibromyalgia syndrome.
No full textAim of Investigation: Recent neuroimaging studies using voxel-based morphometry (VBM) demonstrated reductions in brain gray matter (GM) volume in Fibromyalgia (FS), a chronic pain syndrome thought to result from altered central pain processing.
Little is known about the relative contribution of the two components of cortical GM volume – thickness and surface area – to these structural alterations.
Our aim was to assess alterations in GM morphology (volume, thickness, area) in FS compared to a control group, and to correlate GM morphology with clinical variables of pain, namely duration, intensity (VAS), and tender point count, and with
depression score (Center for Epidemiology Studies-Depression Scale).
Methods: Twenty-three women with FS and 26 healthy pain-free women matched for age and educational level participated in the
study. Pressure pain thresholds were measured with an algometer applied to the 18 defining tender points and to 10 additional points to obtain a total positive tender point count. A high-resolution structural T1-weighted brain scan (360 sagittal slices without gap; isotropic voxel size 0.5mm; FOV 240 x 240 x 180mm; TR 35ms; flip angle 50°; TE 5.7ms) was acquired for each subject, using a 3T Philips Achieva MR scanner. GM volume was assessed applying VBM to modulated data in SPM8 using an
individualised DARTEL template for inter-subject alignment. Surface-based measures of cortical thickness and area were obtained using the Freesurfer 4.5.0 software. Both the VBM and Freesurfer data were spatially smoothed using an 8mm FWHM Gaussian kernel. The statistical analysis of the surface-based data was performed both on vertex-wise values and on values averaged within 64 anatomical Regions of Interest (ROIs). Nuisance influences of age, total intracranial volume (TIV), handedness and menopause were removed.
Results: Compared to the control group, FS patients showed i) reduced GM volume in the left medial and superior frontal gyrus
(BA 6; a trend that became significant after controlling for depression score), ii) reduced surface area in the left pericalcarine cortex, and iii) increased thickness in the left fusiform gyrus and in the right rostral middle frontal cortex. Pain intensity was negatively correlated with thickness in the bilateral paracentral lobule (BA 6); however, brain morphology was correlated neither with pain duration nor with positive tender point count. The only significant age-by-group interaction consisted in the fact that the age-related loss in GM thickness and area in the left lateral occipital cortex was less steep in patients compared to controls, because the patients had lower values already at a younger age.
Conclusions: The present results provide further evidence for altered brain morphology in FS, including brain areas in which this
had not been previously demonstrated, and show a relationship of specific structural changes with the severity of specific
symptoms
Spatial extent of pain influences gray matter volume in fibromyalgia patients.
No full textAim of Investigation: Fibromyalgia (FS) is a syndrome characterised by chronic widespread pain, whose
pathophysiology is still controversial. Previous studies assessing alterations in local gray matter volume (GMV) in
FS have obtained somewhat inconsistent results, possibly due to differences in clinical features. Our aim was to
assess GMV changes in FS compared to a control group, and their correlations with the severity of clinical
aspects, including illness duration, pain intensity and quality, body pain area, number of positive tender points and
depression. Methods: Thirty-four women with FS diagnosed by a rheumatologist and 38 healthy women (controls,
C) without chronic pain matched for age (FS: range 18-55 ys, mean 44; C: 25-60 ys, mean 45.6), menopausal
status, educational level, handedness and caffeine consumption, participated in the study. The control subjects
had experienced no pain (N=9) or episodic/recurrent pain without (N=20) or with use of pain killers (N=9) over the
past year. Depressive symptoms were assessed using the Center for Epidemiology Studies-Depression Scale
(CES-D); the sensory (S), affective (A) and evaluative (E) quality of spontaneous pain were tested using the
Italian adaptation of the McGill Pain Questionnaire (Questionario Italiano del Dolore - QUID). Spatial extent of
pain was assessed using Margolis body pain area drawings. Pressure pain thresholds were measured by means
of an algometer applied to the 18 defining tender points and to 10 additional points to obtain a detailed picture of
spatial distribution of allodynia. A high-resolution structural T1-weighted brain scan (360 sagittal slices without
gap; isotropic voxel size 0.5mm; FOV 240 x 240 x 180mm; TR 35ms; flip angle 50; TE 5.7ms) was acquired for
each subject, using a 3T Philips Achieva MR scanner. GMV was assessed applying voxel-based morphometry
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(VBM) to modulated data in SPM8 using the VBM8 toolbox (voxel-wise critical p < 0.005; cluster size corrected for
multiple comparisons using AlphaSim with 10,000 Monte Carlo simulations). Results: Patients showed no
significant differences in GMV compared to the total control group. In the patient sample, GMV was negatively
correlated with QUID-E score in BA 6 and with the spatial extent of spontaneous pain in the bilateral
parahippocampal gyrus (pHG), and it was positively correlated with illness duration in the cerebellum. GMV was
independent of pain intensity, tender point count, CES-D, QUID-S and QUID-A score. Reported pain extent
ranged from 9-90% of body surface (mean/median: 48%). Patients with below-median pain extent had greater
GMV than patients with above-median values in the bilateral pHG and cerebellum, left paracentral lobule (BA 6)
and cingulate gyrus (BA 31). GMV values of the controls in these brain areas were intermediate between the two
patient groups. Spatial extent of pain was positively correlated with tender point count and with QUID-S and was
independent of all other clinical and nuisance variables included in the study. Conclusions: Some, but not all,
previous VBM studies have reported reduced GMV in the pHG and in the cingulate cortex in FS (Wood, 2010).
Our results point to a possible explanation for these inconsistent findings: depending on how widespread their
pain, FS patients may show either reduced or increased GMV in the pHG and cingulate cortex, i.e. they are more
different from each other than from the control group. Further research is needed to explore the possible causes
of these inter-individual differences within the FS population.
Reference: Wood PB. Variations in brain gray matter associated with chronic pain. Curr Rheumatol Rep
2010;12:462-469
Hypnotic susceptibility explains differences in resting state functional connectivity
No full textIntroduction:
Hypnotic susceptibility (HS) is a measurable cognitive trait defined as the generalized tendency to
respond to hypnotic suggestions [1]. Very little is known about the neural bases of HS [2]. Our aim was to
assess HS-related differences in resting state func tional c onnec tivity.
Methods:
N=35 healthy women (3 ambidextrous, 4 left-handed; age range 19-56 yrs, mean 36.9 yrs) partic ipated
in the study. HS was assessed with the Stanford Hypnotic Susc eptibility Sc ale – Form A (SHSS:A),
mental absorption with the T ellegen Absorption Sc ale (T AS) and trait anxiety with the State-T rait
Anxiety Inventory Form Y (ST AI-Y2). Subjec ts were not in any way pre-selec ted for SHSS sc ore.
T o measure spontaneous BOLD signal fluc tuations at rest, two runs of EPI sc ans were ac quired while
subjec ts lay in the sc anner relaxed with eyes c losed (for eac h run: 200 volumes; T R 2 s; isometric voxel
size 3.6 mm; 35 axial slic es without gap; matrix 80 x 63 voxels; FOV 286 x 229 mm; ac quisition time 7
min), using a 3T Philips Ac hieva MR sc anner. A T 1-weighted brain image (isotropic voxel size 0.5 mm)
was ac quired for inter-subjec t alignment. EPI data were analysed using AFNI. Preproc essing inc luded
the removal of physiologic al, white matter and hardware related noise using RET ROICOR and
ANAT ICOR proc edures, lowpass filtering to remove frequenc ies >0.1 Hz, and 6-mm FWHM spatial
smoothing.
Seed-based func tional c onnec tivity (FC) was quantified as the z-transformed Pearson c orrelation with
the seed signal (average BOLD signal within a sphere of 6mm radius). Seeds were plac ed (a) within key
regions of the Default Mode Network (DMN) taken from the literature; (b) in the two areas (anterior
c ingulate c ortex – ACC; dorsolateral prefrontal c ortex – DLPFC) desc ribed in Hoeft et al. [2]; and (c ) in
15 seeds ad-hoc plac ed along the c ingulate c ortex in eac h hemisphere. HS-related differenc es in FC
were assessed by using SHSS sc ore as a between-subjec ts linear regressor to explain FC z-sc ores.
Furthermore, some of the c lusters whic h resulted signific antly c onnec ted with the above mentioned
seeds, e.g. orbitofrontal c ortex (OFC), were, in turn, used as seeds (d).
Results:
SHSS sc ores ranged from 0-10 (mean 3.6). Eighteen subjec ts had low (SHSS<4), 14 medium
(SHSS=4-7) and 3 high SHSS sc ores (SHSS>7). SHSS was independent of age, educ ational level,
handedness, trait anxiety and mental absorption.
SHSS was positively c orrelated with FC (a) of DMN seeds, i.e., the right medial PFC, left posterior
c ingulate c ortex (PCC) and left posterior insula with c erebellar foc i, and (b) of Hoeft et al.'s [2] ACC
seed with c erebellar regions, and of right DLPFC with left OFC. When foc using on the c ingulate c ortex
(c ), SHSS was positively c orrelated with FC of ACC with mid-c ingulate c ortex (MCC), of various seeds in
the ACC and MCC with c erebellar foc i, and of MCC with bilateral OFC. SHSS was also positively
c orrelated with FC of the OFC foc i (d) with a wide network of regions, inc luding MCC, bilateral DLPFC
(see Fig. 1), pre- and postcentral gyri, superior temporal gyri and insula as well as cerebellum and
contralateral precuneus (Fig. 2).
Conclusions:Among healthy women, individuals with higher HS show higher resting state FC between OFC, DLPFC,
cingulate cortex and cerebellum. Further researc h is needed to c onfirm these relationships in men, and
to assess their cognitive correlates
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
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