The nature of obsessions has led researchers to try to determine if the main problem in obsessive-compulsive disorder (OCD) is impaired inhibitory control. Previous studies report that the effort to suppress is one of the factors that increase the frequency of obsessive thoughts. Based on these results and those of the present study that suggest inferior parietal lobe (IPL) abnormality in OCD and findings of a recent study that reported the importance of the right posterior parietal cortex in cognitive control of a simple mental image, the present cognitive control paradigm study aimed to determine whether there is a difference in brain dynamics between OCD patients and non-obsessive controls while performing tasks that necessitate cognitive control of a simple mental image, and whether the right posterior parietal region is one of the regions in which a difference in activity between the OCD patients and controls would be observed. Functional brain imaging was performed while the participants attempted to suppress, imagine, or manipulate a mental image. The general linear model showed that there was a main effect of group and main effect of task. Accordingly, in all contrasts (suppression minus free-imagination, erasing minus free-imagination, and imagination minus free-imagination), the right IPL, right posterior cingulate cortex, and right superior frontal gyrus activity were lower in the OCD patients than in the healthy controls. These results and the observed correlations between activity levels, and symptom and subjective performance scores are discussed. In conclusion, the results of the present study and those of previous studies suggest that the main problem in OCD might be difficulty activating the right frontoparietal networks during tasks that require cognitive control, which might result in the intrusiveness of obsessive thoughts.
"Recent researches on FMRI data  and functional connectivity analysis  of patients with OCD during different brain states have demonstrated that OCD influence remote regions of brain called default mode network (DMN) like left and right posterior lobes (LIPL, RIPL) and post cingulate corpus (PCC)  . We considered LIPL, RIPL and PCC regions as regions of interest (ROIs) in this study. "
[Show abstract][Hide abstract] ABSTRACT: OCD) is a frequent, chronic disorder producing intrusive thoughts which results in repetitive behaviors. It is thought that this psychological disorder occurs due to abnormal functional connectivity in certain regions of the brain called Default Mode Network (DMN) mainly. Recently, functional MRI (FMRI) studies were performed in order to compare the differences in brain activity between patients with OCD and healthy individuals through different conditions of the brain. Our previous study on extraction of disease signature for OCD that is determining the features for discrimination of OCD patients from healthy individuals based on their resting-sate functional connectivity (rs-FC) data had given encouraging results. In the present study, functional data extracted from FMRI images of subjects under imagination task (maintaining an image in mind, im-FC) is considered. The aim of this study is to compare classification results achieved from both resting and task-related (imagination) conditions. This research has shown quite interesting and promising results using the same classification (SVM) method.
Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE; 08/2014
"these thought suppression difficulties. OCD patients had difficulty activating the right frontoparietal networks, a key area for visuospatial ability, during tasks that required cognitive control (Koçak, Özpolat, Atbas¸o glu, & Çiçek, 2011). Few studies, however, have directly examined the proposed link between impaired inhibitory control, the component of executive functioning designed to inhibit irrelevant information, and difficulty managing obsessional thoughts. "
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND OBJECTIVES: The aim of the current study was to examine cognitive and psychological factors hypothesized to affect responding to intrusions in obsessive-compulsive disorder (OCD). METHODS: A group of individuals diagnosed with OCD (N = 22) was compared to a social phobia (SP) group (N = 25) and a nonclinical control group (N = 24). Participants performed a battery of neuropsychological tasks, completed self-report measures, and engaged in a self-relevant thought suppression task. RESULTS: Participants in the OCD group demonstrated worse working memory and response inhibition on the neuropsychological tasks and had increased intrusions during the suppression task relative to comparison groups. They also reported more distress during the task relative to the nonclinical group, but not the SP group. Regression analyses revealed that beliefs about thought control failures, but not working memory or response inhibition, was associated with increased frequency of intrusions and greater distress during suppression. LIMITATIONS: Future studies may include a more comprehensive battery of cognitive tests and have a larger sample size. CONCLUSIONS: Findings support cognitive-behavioural models of OCD that emphasize the role of meta-beliefs in explaining the struggle with obsessional thoughts.
Journal of Behavior Therapy and Experimental Psychiatry 02/2013; 44(3):343-350. DOI:10.1016/j.jbtep.2013.01.005 · 2.23 Impact Factor
"The residual BOLD time-series were band-pass filtered to leave low-frequency BOLD oscillations (0.004 Hz < f < 0.08 Hz). To perform seed driven connectivity analysis ROIs were defined on PCC and medial prefrontal cortex (MPFC) regions that are the representative DMN areas (Fox et al., 2005 ; Whitfield-Gabrieli et al., 2011) Left and right inferior parietal lobe (IPL) regions were also included as ROIs to ask if there are any connectivity differences in these regions between OCD patients and healthy controls as a follow up analysis for our recent findings (Kocak et al., 2011). Extracting the residual BOLD time course from seed regions, and computing Pearson's correlation coefficients between that time course and the time course of all other voxels produced correlation maps. "
[Show abstract][Hide abstract] ABSTRACT: Recent evidence suggests that the brain intrinsic activity during rest might be as significant as task evoked activities and consumes considerable energy linked to neural signaling processes. We performed an fMRI study recently aiming to compare the differences in brain activity between patients with obsessive-compulsive disorder and healthy volunteers during a simple suppression paradigm. We hypothesized that the patients with obsessive-compulsive disorder would show default mode network (DMN) connectivity dissociations from healthy individuals. OCD patients had higher connectivity (p < 0.05) than controls between right inferior parietal lobe (IPL) and left ventral medial prefrontal cortex (MPFC).
Activitas nervosa superior 01/2012; 54(3-4):118-124.
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