Akademik Merkezler / Academic Centers
Permanent URI for this communityhttps://hdl.handle.net/11413/4999
Browse
Browsing Akademik Merkezler / Academic Centers by Publisher "ELSEVIER IRELAND LTD, ELSEVIER HOUSE, BROOKVALE PLAZA, EAST PARK SHANNON, CO, CLARE, 00000, IRELAND"
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Publication A comparative analysis of sensory visual evoked oscillations with visual cognitive event related oscillations in Alzheimer's disease(ELSEVIER IRELAND LTD, ELSEVIER HOUSE, BROOKVALE PLAZA, EAST PARK SHANNON, CO, CLARE, 00000, IRELAND, 2009-09-25) Yener, Görsev G.; Güntekin, Bahar; Tülay, Elif; BAŞAR, EROL; TR142226; TR142311; TR204666; TR143760We compared visual evoked oscillatory responses of subjects with Alzheimer's disease (AD) (n = 22) to healthy elderly controls (n = 19) elicited by simple light stimuli. The visual evoked oscillatory responses in AD subjects without cholinergic treatment (n = 11) show significant differences (df = 2.38. F = 4.957, P = 0.012) from the controls and the AD subjects treated with a cholinesterase inhibitor (n = 11). Higher theta oscillatory responses in untreated AD subjects are seen on the electrode locations over bi-parietal and right occipital regions after simple light stimuli with less, if any, cognitive load. These changes were restricted to the theta frequency range only and are related to location, frequency bands and drug effects. In our previous work we observed that visual event related oscillations elicited after the visual stimuli with a higher cognitive load, i.e. an oddball target, display lower amplitudes: between controls and AD subjects in delta frequency band without a drug effect, over the left and mid-central region. These differences between the visual evoked oscillations and the visual event related oscillations imply that there are at least two different cognitive circuits that are activated upon visual stimuli in AD patients. (c) 2009 Published by Elsevier Ireland Ltd.Publication Event Related Oscillations in Euthymic Patients With Bipolar Disorder(ELSEVIER IRELAND LTD, ELSEVIER HOUSE, BROOKVALE PLAZA, EAST PARK SHANNON, CO, CLARE, 00000, IRELAND, 2008-10-17) Özerdem, Ayşegül; Kocaaslan, Sibel; Tunca, Zeliha; BAŞAR, EROL; TR140995; TR12868; TR142226Bipolar disorder involves dysfunction in gamma amino butyric acid (GABA)/glutamatergic systems and neural circuits that regulate cognitive processing. Valproate, a mood stabilizing anticonvulsant, modulates GABA/glutamate and shows neuroprotective effect. Electroencephalographic oscillatory activity assessment is an alternative brain imaging technique with high time resolution. It presents integrative brain functioning. We aimed to assess the oscillatory responses of patients with bipolar disorder in euthymic state of bipolar disorder and the changes after treatment with valproate. Event related potentials to visual odd-ball paradigm in 10 euthymic medication free, bipolar patients were measured before and after 6 weeks of valproate monotherapy and compared with sex- and age-matched healthy controls. Delta frequency bands, as representative of signal detection and decision-making, were obtained by digital filtering. At baseline, patients showed higher delta responses to target stimuli in all but significantly left frontal channels in comparison to controls. After 6 weeks of treatment, delta responses decreased significantly in central frontal (Fz) (p: 0.028), left frontal (F3) (p: 0.028), left (T3) (p: 0.015), right anterior (T4) (p: 0.011), and left posterior temporal (T5) (p: 0.011) channels compared to baseline and became no different to the controls, which did not differ between two assessments. The findings point to a diffuse increase in low frequency electrical activity which was prominent in the left frontal location in euthymic patients with bipolar disorder. Reduction of the electrical activity of the left frontal and bilateral anterior temporal areas with treatment may be through modulation of glutamatergic and GABAergic mechanisms and indicative of valproate's neuroprotective effect. (C) 2008 Elsevier Ireland Ltd. All rights reserved.Publication Gender Differences Influence Brain's Beta Oscillatory Responses in Recognition of Facial Expressions(ELSEVIER IRELAND LTD, ELSEVIER HOUSE, BROOKVALE PLAZA, EAST PARK SHANNON, CO, CLARE, 00000, IRELAND, 2007-09-07) Güntekin, Bahar; BAŞAR, EROL; TR142226; TR204666There are only few studies describing gender differences in recognition of facial expressions. Our study has the aim to analyze the effect of gender differences in oscillatory brain responses. Three sets of Ekman and Friesens's facial expressions (neutral, angry, and happy) were presented to 26 healthy subjects (13 men) while recording from 13 different scalp locations. Occipital beta response (15-24 Hz) was significantly larger for women than for men during the presentation of face expressions. Our results demonstrate that processing of emotional face expressions clearly differs between men and women. Accordingly, the results indicate the necessity of introducing standardization between male and female subjects by means of oscillatory dynamics. In turn, this standardization may be useful for cognitive and clinical studies. (C) 2007 Elsevier Ireland Ltd. All rights reserved.