Browsing by Subject "Functional connectivity"
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Item Open Access Changes in FMRI resting state networks due to audiovisual association induced effects on visual motion perception(2016-08) Yıldırım, Fazilet ZeynepAssociative learning, the process by which an association between two stimuli or a behavior and a stimulus is learned, is one of today's exciting and important topics of neuroscience. The in uence of multisensory associations on perceptual experience has revealed unexpected levels of sensory plasticity in the adult brain. By using an audiovisual association paradigm, we designed experiments to assess motion perception and BOLD activity under various associative learning conditions. Eleven subjects (3 males) participated in the audiovisual association training followed by resting state fMRI scans. Before and after the association training, random-dot motion with varying coherence values and static tones of distinct frequencies were presented. Subjects were required to indicate the direction of random-dot motion. During the association phase, random-dots moving up or down with 100% coherence was paired with either high or low frequency static tone. The behavioral data showed that the perception of random-dot motion with low coherence was signi cantly changed in favor of exposed audiovisual association. The analyses on resting state functional data indicated that identi- ed canonical networks (i.e., visual, auditory, sensory, motor, executive, memory, and default mode) did not di er signi cantly between pre- and post- association training, and inter-hemispheric coherence values between early stage visual motion areas were not increased. On the other hand, the connectivity strength between auditory and visual networks increased signi cantly after the acquired audiovisual association. Accordingly, these ndings suggest that even brief association training can lead to changes in connectivity between low-level sensory areas.Item Open Access Cortical connectivity in the face of congenital structural changes—A case of homozygous LAMC3 mutation(John Wiley & Sons Ltd., 2021-08) Demirayak, P.; Oğuz, Kader Karlı; Üstün, Fatma Seyhun; Ürgen, Buse Merve; Topaç, Yasemin; Gilani, İrtiza; Kansu, T.; Saygı, S.; Özçelik, Tayfun; Boyacı, Hüseyin; Doerschner, KatjaThe homozygous LAMC3 gene mutation is associated with severe bilateral smoothening and thickening of the lateral occipital cortex . Despite this and further significant changes in gray matter structure, a patient harboring this mutation exhibited a range of remarkably intact perceptual abilities . One possible explanation of this perceptual sparing could be that the white matter structural integrity and functional connectivity in relevant pathways remained intact. To test this idea, we used diffusion tensor and functional magnetic resonance imaging to investigate functional connectivity in resting-state networks in major structural pathways involved in object perception and visual attention and corresponding microstructural integrity in a patient with homozygous LAMC3 mutation and sex, age, education, and socioeconomically matched healthy control group. White matter microstructural integrity results indicated widespread disruptions in both intra- and interhemispheric structural connections except inferior longitudinal fasciculus. With a few exceptions, the functional connectivity between the patient's adjacent gray matter regions of major white matter tracts of interest was conserved. In addition, functional localizers for face, object, and place areas showed similar results with a representative control, providing an explanation for the patient's intact face, place, and object recognition abilities. To generalize this finding, we also compared functional connectivity between early visual areas and face, place, and object category-selective areas, and we found that the functional connectivity of the patient was not different from the control group. Overall, our results provided complementary information about the effects of LAMC3 gene mutation on the human brain including intact temporo-occipital structural and functional connectivity that are compatible with preserved perceptual abilities.Item Open Access The effect of SARS-CoV-2 virus on resting-state functional connectivity during adolescence: Investigating brain correlates of psychotic-like experiences and SARS-CoV-2 related inflammation response(Elsevier B.V., 2023-12) Yilmaz Kafali, H.; Dasgin, Hacer; Sahin Cevik, Didenur; Sozan, S. S.; Oguz, Kader K.; Mutlu, M.; Ozkaya Parlakay, A.; Toulopoulou, TimotheaWe first aimed to investigate resting-state functional connectivity (rs-FC) differences between adolescents exposed to SARS-CoV-2 and healthy controls. Secondly, the moderator effect of PLEs on group differences in rs-FC was examined. Thirdly, brain correlates of inflammation response during acute SARS-CoV-2 infection were investigated. Eighty-two participants aged between 14 and 24 years (SARS-CoV-2 (n = 35), controls (n = 47)) were examined using rs-fMRI. Seed-based rs-FC analysis was performed. The positive subscale of Community Assessment of Psychotic Experiences-42 (CAPE-Pos) was used to measure PLEs. The SARS-CoV-2 group had a lesser rs-FC within sensorimotor network (SMN), central executive network (CEN) and language network (LN), but an increased rs-FC within visual network (VN) compared to controls. No significant differences were detected between the groups regarding CAPE-Pos-score. However, including CAPE-Pos as a covariate, we found increased rs-FC within CEN and SN in SARS-CoV-2 compared to controls. Among the SARS-CoV-2 group, neutrophil/lymphocyte and thrombocyte*neutrophil/lymphocyte ratio was correlated with decreased/increased FC within DMN and SN, and increased FC within CEN. Our results showed rs-FC alterations within the SMN, CEN, LN, and VN among adolescents exposed to SARS-CoV-2. Moreover, changes in rs-FC associated with PLEs existed in these adolescents despite the absence of clinical changes. Furthermore, inflammation response was correlated with alterations in FC within the triple network system.Item Open Access Tracking pain in resting state networks in patients with hereditary and diabetic neuropathy(Turkish Neuropsychiatric Society, 2019) Has, Arzu Ceylan; Öztekin, N.; Temuçin, Ç. M.; Karlı, O. K.; Taşkıran Sağ, A.Introduction:Chronic pain is associated with maladaptive plastic changes in the brain. It is usually more prominent in acquired pathologies of nerve fibers as in diabetic neuropathy despite less severe degeneration than hereditary neuropathies. Based on clinical differences concerning pain perception, we hypothesized that functional connectivity analysis would reveal distinct patterns in resting-state networks in these groups. Methods: Ten diabetic patients with painful neuropathy (5F/5M; mean age=50.10±6.05 years), 10 patients with hereditary neuropathy (5F/5M; mean age=37.80±14.01 years), 18 age-and gender-matched healthy controls (eight for painful diabetic neuropathy and 10 for hereditary neuropathy) and seven diabetic controls without painful neuropathy were enrolled in the study. All subjects (n=45) underwent a 5-min resting-state scan in a 3T magnetic resonance scanner. The images were analyzed with seed-based functional connectivity method. The grouplevel maps of the default mode network and insula-cingulate network were identified for each group. Results: Patients with hereditary neuropathy displayed increased connectivity between left insula and left anterior cingulate cortex and inversely correlated activity between left insula and left inferior parietal lobule compared to their controls. In patients with painful diabetic neuropathy, the major findings were the increased connectivity between left anterior cingulate cortex and posterior cingulate cortex/precuneus, and the increased connectivity between medial prefrontal cortex and left medial temporal region compared to their controls. Conclusion: This study revealed that hereditary and diabetic painful neuropathy patients exhibit different patterns of functional connectivity. The clinical differences in these groups regarding the presence of neuropathic pain may relate to this difference in cortical organization.