26 research outputs found
Apego y psicopatología en adolescentes y jóvenes que han sufrido maltrato: implicaciones clínicas
ResumenSe estudia la relación entre apego y psicopatología en una muestra de 40 adolescentes y jóvenes que han sufrido maltrato intrafamiliar. El apego se evalúa mediante el cuestionario RQ de Bartholomew, que distingue cuatro estilos de apego en función de la imagen positiva o negativa del self y de los demás: apego seguro, preocupado, temeroso y evitativo. Los resultados del estudio muestran que el apego inseguro, sobre todo el subtipo evitativo, es el más prevalente. Algo más de la mitad de la muestra (52.5%) presenta sintomatología clínicamente significativa (evaluada mediante el SCL-90-R), en especial hostilidad, obsesión-compulsión, ideación paranoide, psicoticismo y sensibilidad interpersonal. Los estilos de apego con una visión negativa del self (preocupado y temeroso) tienden a presentar más sintomatología psicopatológica. Se discuten las implicaciones clínicas de estos resultados.AbstractIn this research, the relationship between attachment and psychopathology was studied in a sample of 40 adolescents and young adults who have suffered from intrafamily maltreatment. Attachment was assessed with Bartholomew's RQ, which distinguishes four attachment styles depending on the positive or negative image of the self and others: secure, preoccupied, fearful and dismissive attachment. Results show that insecure attachment, particularly the dismissive subtype, is the most prevalent one. Slightly more than half of the sample (52.5%) shows clinically significant symptoms (as assessed with the SCL-90-R), particularly hostility, obsessive-compulsive, paranoid ideation, psychoticism, and interpersonal sensitivity. Attachment styles with a negative vision of the self (preoccupied and fearful) tend to show more psychopathological symptoms. The clinical implications of these results are also discussed
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Increased functional connectivity patterns in mild Alzheimer’s disease: a rsfMRI study
Background: Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder. In view of our rapidly aging population, there is an urgent need to identify Alzheimer’s disease (AD) at an early stage. A potential way to do so is by assessing the functional connectivity (FC), i.e., the statistical dependency between two or more brain regions, through novel analysis techniques. Methods: In the present study, we assessed the static and dynamic FC using different approaches. A resting state (rs)fMRI dataset from the Alzheimer’s disease neuroimaging initiative (ADNI) was used (n = 128). The blood-oxygen-level-dependent (BOLD) signals from 116 regions of 4 groups of participants, i.e., healthy controls (HC; n = 35), early mild cognitive impairment (EMCI; n = 29), late mild cognitive impairment (LMCI; n = 30), and Alzheimer’s disease (AD; n = 34) were extracted and analyzed. FC and dynamic FC were extracted using Pearson’s correlation, sliding-windows correlation analysis (SWA), and the point process analysis (PPA). Additionally, graph theory measures to explore network segregation and integration were computed. Results: Our results showed a longer characteristic path length and a decreased degree of EMCI in comparison to the other groups. Additionally, an increased FC in several regions in LMCI and AD in contrast to HC and EMCI was detected. These results suggest a maladaptive short-term mechanism to maintain cognition. Conclusion: The increased pattern of FC in several regions in LMCI and AD is observable in all the analyses; however, the PPA enabled us to reduce the computational demands and offered new specific dynamic FC findings.info:eu-repo/semantics/publishedVersio
Revisiting non-linear functional brain co-activations: directed, dynamic and delayed
The center stage of neuro-imaging is currently occupied by studies of
functional correlations between brain regions. These correlations define the
brain functional networks, which are the most frequently used framework to
represent and interpret a variety of experimental findings. In previous work we
first demonstrated that the relatively stronger BOLD activations contain most
of the information relevant to understand functional connectivity and
subsequent work confirmed that a large compression of the original signals can
be obtained without significant loss of information. In this work we revisit
the correlation properties of these epochs to define a measure of nonlinear
dynamic directed functional connectivity (nldFC) across regions of interest. We
show that the proposed metric provides at once, without extensive numerical
complications, directed information of the functional correlations, as well as
a measure of temporal lags across regions, overall offering a different
perspective in the analysis of brain co-activation patterns. In this paper we
provide for a proof of concept, based on replicating and completing existing
results on an Autism database, to discuss the main features and advantages of
the proposed strategy for the study of brain functional correlations. These
results show new interpretations of the correlations found on this sample.Comment: 12 pages, 8 figure
Residual strength of WC-Co cemented carbides after being subjected to abrupt temperature changes
Thermal shock and thermal fatigue
are recognized as common failure modes
for WC
-
Co cemented carbides
(hardmetals) in several applications
in
volving service temperature changes.
However, information on
microstructure
-
performance for these materials when subjected to abrupt changes in temper
ature is rather
limited.
In this investigation, the thermal shock resistance of two WC
-
Co cemented carbides
is studied on the
basis of their residual strength after being subjected to temperature changes. The materials studied
correspond to grades
with dif
ferent grain size (medium and ultrafine) but similar binder content.
Thermal
shock variables include two temperature difference ranges (400ºC and 550ºC) as well as number of abrupt
changes (1, 3 and 10). Residual strength results were related to
parameters
extracted from Hasselman’s
theory
.
It is found that
medium
-
sized
hardmetal
exhibits a higher strength loss in the first quenching cycle
but a greater damage tolerance to repeated thermal shocks than the ultrafine
-
sized.
The assessed residual
strength tren
ds are in agreement with those expected from
evaluation of
Hasselman’s parameters
for
quantifying resistance to either crack initiation or crack propagation induced by thermal shockPostprint (published version
Revisiting nonlinear functional brain co-activations: Directed, dynamic, and delayed
The center stage of neuro-imaging is currently occupied by studies of functional correlations between brain regions. These correlations define the brain functional networks, which are the most frequently used framework to represent and interpret a variety of experimental findings. In the previous study, we first demonstrated that the relatively stronger blood oxygenated level dependent (BOLD) activations contain most of the information relevant to understand functional connectivity, and subsequent work confirmed that a large compression of the original signals can be obtained without significant loss of information. In this study, we revisit the correlation properties of these epochs to define a measure of nonlinear dynamic directed functional connectivity (nldFC) across regions of interest. We show that the proposed metric provides at once, without extensive numerical complications, directed information of the functional correlations, as well as a measure of temporal lags across regions, overall offering a different and complementary perspective in the analysis of brain co-activation patterns. In this study, we provide further details for the computations of these measures and for a proof of concept based on replicating existing results from an Autistic Syndrome database, and discuss the main features and advantages of the proposed strategy for the study of brain functional correlations.Fil: Cifre, Ignacio. Universitat Ramon Llull; España. Universidad Nacional de San Martin. Escuela de Ciencia y Tecnologia. Centro de Estudios Multidisciplinarios En Sistemas Complejos y Ciencias del Cerebro.; ArgentinaFil: Miller Flores, Maria T.. Universidad Nacional de San Martin. Escuela de Ciencia y Tecnologia. Centro de Estudios Multidisciplinarios En Sistemas Complejos y Ciencias del Cerebro.; ArgentinaFil: Penalba, Lucia. Universitat Ramon Llull; EspañaFil: Ochab, Jeremi K.. Jagiellonian University; PoloniaFil: Chialvo, Dante Renato. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Escuela de Ciencia y Tecnologia. Centro de Estudios Multidisciplinarios En Sistemas Complejos y Ciencias del Cerebro.; Argentin
Power Spectral Density and Functional Connectivity Changes due to a Sensorimotor Neurofeedback Training: A Preliminary Study
Neurofeedback is a form of neuromodulation based on learning to modify some aspects of cortical activity. Sensorimotor rhythm
(SMR) oscillation is one of the most used frequency bands in neurofeedback. Several studies have shown that subjects can learn to
modulate SMR power to control output devices, but little is known about possible related changes in brain networks. The aim of this
study was to investigate the enhanced performance and changes in EEG power spectral density at somatosensory cerebral areas due
to a bidirectional modulation-based SMR neurofeedback training. Furthermore, we also analyzed the functional changes in
somatosensory areas during resting state induced by the training as exploratory procedure. A six-session neurofeedback protocol
based on learning to synchronize and desynchronize (modulate) the SMR was implemented. Moreover, half of the participants
were enrolled in two functional magnetic resonance imaging resting-state sessions (before and after the training). At the end of
the training, participants showed a successful performance enhancement, an increase in SMR power specific to somatosensory
locations, and higher functional connectivity between areas associated with somatosensory activity in resting state. Our research
increases the better understanding of the relation between EEG neuromodulation and functional changes and the use of SMR
training in clinical practice.This work was supported by grants from Bial Foundation
(#385-14), PSI2017-88388-C4-1-R (AEI/FEDER, UE), and
the Spanish Ministerio de Economía, Industria y Competitividad
(ref: PSI2013-48260-C3-1-R and PSI2014-57231-R)
Modular Organization of Brain Resting State Networks in Chronic Back Pain Patients
Recent work on functional magnetic resonance imaging large-scale brain networks under resting conditions demonstrated its potential to evaluate the integrity of brain function under normal and pathological conditions. A similar approach is used in this work to study a group of chronic back pain patients and healthy controls to determine the impact of long enduring pain over brain dynamics. Correlation networks were constructed from the mutual partial correlations of brain activity's time series selected from ninety regions using a well validated brain parcellation atlas. The study of the resulting networks revealed an organization of up to six communities with similar modularity in both groups, but with important differences in the membership of key communities of frontal and temporal regions. The bulk of these findings were confirmed by a surprisingly naive analysis based on the pairwise correlations of the strongest and weakest correlated healthy regions. Beside confirming the brain effects of long enduring pain, these results provide a framework to study the effect of other chronic conditions over cortical function
Non-linear Functional Brain Co-activations in Short-Term Memory Distortion Tasks
Recent works shed light on the neural correlates of true and false recognition and the influence of time of day on cognitive performance. The current study aimed to investigate the modulation of the false memory formation by the time of day using a non-linear correlation analysis originally designed for fMRI resting-state data. Fifty-four young and healthy participants (32 females, mean age: 24.17 ± 3.56 y.o.) performed in MRscanner the modified Deese-Roediger-McDermott paradigm in short-term memory during one session in the morning and another in the evening. Subjects’ responses were modeled with a general linear model, which includes as a predictor the nonlinear correlations of regional BOLD activity with the stimuli, separately for encoding and retrieval phases. The results show the dependence of the non-linear correlations measures with the time of day and the type of the probe. In addition, the results indicate differences in the correlations measures with hippocampal regions between positive and lure probes. Besides confirming previous results on the influence of time-of-day on cognitive performance, the study demonstrates the effectiveness of the non-linear correlation analysis method for the characterization of fMRI task paradigms.Fil: Ceglarek, Anna. Jagiellonian University; PoloniaFil: Ochab, Jeremi K.. Jagiellonian University; PoloniaFil: Cifre, Ignacio. Universitat Ramon Llull; EspañaFil: Fafrowicz, Magdalena. Jagiellonian University; PoloniaFil: Sikora Wachowicz, Barbara. Jagiellonian University; PoloniaFil: Lewandowska, Koryna. Jagiellonian University; PoloniaFil: Bohaterewicz, Bartosz. Jagiellonian University; PoloniaFil: Marek, Tadeusz. Jagiellonian University; PoloniaFil: Chialvo, Dante Renato. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Físicas. - Universidad Nacional de San Martín. Instituto de Ciencias Físicas; Argentin