Browsing by Subject "Resting state functional connectivity"
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Item Open Access Effects of genetic liability to psychosis proneness and psychosis proneness on functional connectivity of the salience network(2022-12) Aydoğan, İlaydaThe effect of psychosis proneness, a psychometrically defined index of subclinical psychosis, has limited research on its effect on brain connectivity in healthy populations. In addition, functional connectivity research in psychosis proneness mainly focuses on brain networks such as the default-mode network (DMN) and the central executive network (CEN) but not on the salience network (SN). On a similar note, research on genetic susceptibility to psychosis in healthy populations and the combinatory analysis between brain connectivity and genetic liability have not been explored thoroughly. This thesis assessed the relationship between psychosis proneness and genetic liability to psychosis to functional connectivity of the salience network. Seventy-two pairs of twins, siblings, and triplets were included in the analysis for genetic liability and functional connectivity. Participants’ psychosis proneness was assessed via the Community Assessment of Psychic Experience (CAPE-42) questionnaire, and genetic liability scores (PRS-SCZ) were calculated through PLINK and PRSIce-2 software. Global patterns of connectivity, seed-based connectivity, and network topology of the salience network were examined. The findings have revealed that the connectivity levels within the salience network differed in individuals with high psychosis proneness com- pared to individuals with low psychosis proneness. Further analysis has shown that PRS-SCZ did not show a significant difference between high and low psy- chosis proneness groups. The results show that connectivity levels in the salience network differ in individuals with psychometrically defined psychosis proneness. These results were not explained by differences in genetic loading among the participants.Item Open Access Functional changes in the human cortex over the course of visual perceptual learning(2020-03) Akkoyunlu, BeyzaIn this study we assessed functional changes through visual perceptual learning with bisection discrimination task. Before learning, after third session of learning and after learning ended, behavioral threshold and fMRI data has been collected. Our results showed that while participants showed threshold decrease in the midlearning session, the post-learning thresholds are turned to pre-learning levels. These results might be due to fatigue which caused by our experiment. Besides to training condition, we also tested location and task specificity. The results showed that only 150◦polar angle location showed significant change between sessions. Along with the behavioral data, we collected task-based fMRI data while participants performing training and control conditions in the scanner. The analysis showed task-based BOLD response changed with session. However, post-hoc tests did not reveal significant results. The resting-state functional connectivity analysis showed that the functional connectivity between V1 and V2 regions is significantly increased. The Post Hoc analysis showed significant change in the 210◦and 150◦polar angle conditions. The changes in the behavioral and functional connectivity measurements at 150◦polar angle conditions, these results might indicate the effect of the inter-hemispheric connections. Moreover, our analysis on resting state data also revealed that, while there is no change between pre-learning and mid-learning sessions, connectivity changes significantly in the post-learning session compared to other sessions. This finding supports the idea that functional connectivity changes related to perceptual learning might be occurring at the late phases of the learning. Overall, to rule out the confounds in the behavioral measurements and to link the behavioral data with the neural data, additional measurements should be taken in the future.