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Browsing Akademik Merkezler / Academic Centers by Author "Atagün, Murat İlhan"
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Publication Open Access Brain's alpha activity is highly reduced in euthymic bipolar disorder patients(Springer, Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands, 2012-02) Güntekin, Bahar; Turp Gölbaşı, Bilge; Atagün, Murat İlhan; Özerdem, Ayşegül; Tülay, Elif; BAŞAR, EROL; TR142226; TR204666; TR25145; TR140995; TR142311Brain's alpha activity and alpha responses belong to major electrical signals that are related to sensory/cognitive signal processing. The present study aims to analyze the spontaneous alpha activity and visual evoked alpha response in drug free euthymic bipolar patients. Eighteen DSM-IV euthymic bipolar patients (bipolar I n = 15, bipolar II n = 3) and 18 healthy controls were enrolled in the study. Patients needed to be euthymic at least for 4 weeks and psychotrop free for at least 2 weeks. Spontaneous EEG (4 min eyes closed, 4 min eyes open) and evoked alpha response upon application of simple visual stimuli were analyzed. EEG was recorded at 30 positions. The digital FFT-based power spectrum analysis was performed for spontaneous eyes closed and eyes open conditions and the response power spectrum was also analyzed for simple visual stimuli. In the analysis of spontaneous EEG, the ANOVA on alpha responses revealed significant results for groups (F(1,34) = 8.703; P < 0.007). Post-hoc comparisons showed that spontaneous EEG alpha power of healthy subjects was significantly higher than the spontaneous EEG alpha power of euthymic patients. Furthermore, visual evoked alpha power of healthy subjects was significantly higher than visual evoked alpha power of euthymic patients (F(1,34) = 4.981; P < 0.04). Decreased alpha activity in spontaneous EEG is an important pathological EEG finding in euthymic bipolar patients. Together with an evident decrease in evoked alpha responses, the findings may lead to a new pathway in search of biological correlates of cognitive impairment in bipolar disorder.Publication Metadata only Changes in brain oscillations and connectivity deficit in bipolar disorder(Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2012-09) Güntekin, Bahar; Atagün, Murat İlhan; Özerdem, Ayşegül; BAŞAR, EROL; 204666; 25145; 140995; 142226Publication Metadata only Decrease of Alpha/Beta Ratio in EEG Activity in Drug Free Euthymic Bipolar Patients(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 Usa, 2012-04-15) Tülay, Elif; Özerdem, Ayşegül; Atagün, Murat İlhan; Güntekin, Bahar; BAŞAR, EROL; 142226; 140995; 25145; 204666Publication Metadata only Decrease of Event Related Delta Oscillations in Euthymic Patients with Bipolar Disorder(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 USA, 2013-05-01) Atagün, Murat İlhan; Güntekin, Bahar; Masali, Belinda; Tülay, Emine Elif; BAŞAR, EROL; 142226; 25145; 204666; 142311Decreased delta oscillation upon cognitive load is common in patients with Alzheimer׳s disease, mild cognitive impairment, and schizophrenia. However, there is no previous study analyzing the delta responses in euthymic medication-free patients with bipolar disorder. Participants comprised of 22 euthymic medication-free patients with DSM-IV diagnoses of bipolar disorder and 21 healthy controls who were matched to the patients for sex, age, and education. Electroencephalographic activity was recorded at 30 electrode sites using an application of an auditory oddball paradigm. The maximum peak-to-peak amplitudes for each subject׳s averaged delta response (0.5-3.5Hz) were measured. There was a significant inter-group difference in evoked and event-related delta (0.5-3.5Hz) responses. Post-hoc comparisons revealed that the event-related delta oscillatory responses of the bipolar patient group were significantly lower than those of the healthy control group over the temporo-parietal and occipital electrode sites. Euthymic bipolar patients showed reduced event-related delta oscillatory responses in comparison to healthy subjects under cognitive load. The decrease of delta oscillations may be a common phenomenon that can be observed in different neuropsychiatric disorders with cognitive dysfunction.Publication Metadata only Decrease of long distance event related gamma coherence in bipolar patients(Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2010-09) Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; Turp, Bilge; Oral, Esat Timuçin; BAŞAR, EROL; 140995; 204666; 25145; 22231; 142226Publication Metadata only Decrease of Long Distance Gamma (28-48 Hz) Coherence in Euthymic Drug Free Bipolar Patients upon Cognitive Load(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 USA, 2010-05-01) Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; Turp, Bilge; Oral, Esat Timuçin; BAŞAR, EROL; 140995; 204666; 25145; 22231; 142226Publication Open Access Decrease of Theta Response in Euthymic Bipolar Patients During an Oddball Paradigm(Springer, Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands, 2013-06) Atagün, Murat İlhan; Güntekin, Bahar; Özerdem, Ayşegül; Tülay, Emine Elif; BAŞAR, EROL; 142226; 25145; 204666; 140995; 142311Theta oscillations are related to cognitive functions and reflect functional integration of frontal and medial temporal structures into coherent neurocognitive networks. This study assessed event-related theta oscillations in medication-free, euthymic patients with bipolar disorder upon auditory oddball paradigm. Twenty-two DSM-IV euthymic bipolar I (n = 19) and II (n = 3) patients and twenty-two healthy subjects were included. Patients were euthymic for at least 6 months, and psychotropic-free for at least 2 weeks. EEG was recorded at 30 electrode sites. Auditory oddball paradigm and sensory stimuli were used. Event-related Oscillations were analyzed using adaptive filtering in two different theta frequency bands (4-6 Hz, 6-8 Hz). In healthy subjects, slow theta (4-6 Hz) responses were significantly higher than those of euthymic patients upon target, non-target and sensory stimuli (p < 0.05). Fast theta (6-8 Hz) responses of healthy subjects were significantly higher than those of euthymic patients upon target-only stimuli (p < 0.05). Reduced theta oscillations during auditory processing provide strong quantitative evidence of activation deficits in related networks in bipolar disorder. Fast theta responses are related to cognitive functions, whereas slow theta responses are related to sensory processes more than cognitive processes.Publication Metadata only Evoked and Event Related Theta Oscillations are Decreased in Drug-Free Euthymic Bipolar Patients(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 USA, 2011-05-01) Atagün, Murat İlhan; Özerdem, Ayşegül; Güntekin, Bahar; BAŞAR, EROL; 25145; 140995; 204666; Erol Başar 142226Publication Metadata only Increase of Beta Response upon Application of Lithium in Euthymic Bipolar Patients(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 USA, 2011-05-01) Tan, Devran; Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; Tülay, Elif; Karadağ, Figen; BAŞAR, EROL; 103606; 140995; 204666; 25145; 111061; Erol Başar 142226Publication Metadata only Increased Beta Frequency (15-30 Hz) Oscillatory Responses in Euthymic Bipolar Patients Under Lithium Monotherapy(Sage Publications Inc, 2455 Teller Rd, Thousand Oaks, Ca 91320 USA, 2016-04) Tan, Devran; Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; Tülay, Elif; Karadağ, Figen; BAŞAR, EROL; 103606; 140995; 204666; 25145; 111061; 142226The effect of lithium on neurocognition is not still fully explored. Brain oscillatory activity is altered in bipolar disorder. We aimed to assess the oscillatory responses of euthymic bipolar patients and how they are affected by lithium monotherapy. Event-related oscillations in response to visual target stimulus during an oddball paradigm in 16 euthymic drug-free and 13 euthymic lithium-treated bipolar patients were compared with 16 healthy controls. The maximum peak-to-peak amplitudes were measured for each subject's averaged beta (15-30 Hz) responses in the 0- to 300-ms time window over frontal (F3, Fz, F4), central (C3, Cz, C4), temporal (T7, T8), temporo-parietal (TP7, TP8), parietal (P3, Pz, P4), and occipital (O1, Oz, O2) areas. Patients under lithium monotherapy had significantly higher beta responses to visual target stimuli than healthy controls (P = .017) and drug-free patients (P = .015). The increase in beta response was observed at all electrode locations, however, the difference was statistically significant for the left (T7; P = .016) and right (T8; P = .031) temporal beta responses. Increased beta responses in drug-free patients and further significant increase in lithium-treated patients may be indicative of a core pathophysiological process of bipolar disorder and how it is affected by lithium. Whether the finding corresponds to lithium's corrective effect on the underlying pathology or to its neurocognitive side effect remains to be further explored. In either case, the finding is a sign that the oscillatory activity may be useful in tracking medication effect in bipolar disorder.Publication Metadata only Lithium Excessively Enhances Alpha and Beta Oscillatory Responses in Bipolar Disorder(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 Usa, 2013) Atagün, Murat İlhan; Güntekin, Bahar; Tan, Devran; Tülay, Elif; BAŞAR, EROL; 25145; 204666; 103606; 142226Background: Previous resting-state electroencephalography studies have consistently shown that lithium enhances delta and theta oscillations in default mode networks. Cognitive task based networks differ from resting-state networks and this is the first study to investigate effects of lithium on evoked and event-related beta oscillatory responses of patients with bipolar disorder. Methods: The study included 16 euthymic patients with bipolar disorder on lithium monotherapy, 22 euthymic medication-free patients with bipolar disorder and 21 healthy participants. The maximum peak-to-peak amplitudes were measured for each subject's averaged beta responses (14-28 Hz) in the 0-300 ms time window. Auditory simple and oddball paradigm were presented to obtain evoked and event-related beta oscillatory responses. Results: There were significant differences in beta oscillatory responses between groups (p=0.010). Repeated measures ANOVA revealed location (p=0.007), lateralityXgroup (p=0.043) and stimulusXlocation (p=0.013) type effects. Serum lithium levels were correlated with beta responses. Limitations: The lithium group had higher number of previous episodes, suggesting that patients of the lithium were more severe cases than patients of the medication-free group. Discussion: Lithium stimulates neuroplastic cascades and beta oscillations become prominent during neuroplastic changes. Excessively enhanced beta oscillatory responses in the lithium-treated patients may be indicative of excessive activation of the neuron groups of the certain cognitive networks and dysfunctional GABAergic modulation during cognitive activity. Lithium Excessively Enhances Event Related Beta Oscillations in Patients with Bipolar Disorder | Request PDF. Available from: https://www.researchgate.net/publication/264897974_Lithium_Excessively_Enhances_Event_Related_Beta_Oscillations_in_Patients_with_Bipolar_Disorder [accessed Jul 12 2018].Publication Metadata only Lithium excessively enhances event related beta oscillations in patients with bipolar disorder(Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2015-01-01) Atagün, Murat İlhan; Güntekin, Bahar; Tan, Devran; Tülay, Emine Elif; BAŞAR, EROL; 25145; 204666; 103606; 142226Background: Previous resting-state electroencephalography studies have consistently shown that lithium enhances delta and theta oscillations in default mode networks. Cognitive task based networks differ horn resting-state networks and this is the first study to investigate effects or lithium on evoked and event-related beta oscillatory responses of patients with bipolar disorder. Methods: The study included 16 euthymic patients with bipolar disorder on lithium monotherapy, 22 euthymic medication-free patients with bipolar disorder and 21 healthy participants. The maximum peak-to-peak amplitudes were measured for each subject's averaged beta responses (14-28 Hz) in the 0-300 ms time window. Auditory simple and oddball paradigm were presented to obtain evoked and event-related beta oscillatory responses. Results: There were significant differences in beta oscillatory responses between groups (p=0.010). Repeated measures ANOVA revealed location (p=0.007), laterality X group (p=0.043) and stimulus X location (p=0.013) type effects. Serum lithium levels were correlated with beta responses. Limitations: The lithium group had higher number of previous episodes, suggesting that patients of the lithium were more severe cases than patients of the medication-free group. Discussion: Lithium stimulates neuroplastic cascades and beta oscillations become prominent during neuroplastic changes. Excessively enhanced beta oscillatory responses in the lithium-treated patients may be indicative of excessive activation of the neuron groups of the certain cognitive networks and dysfunctional GABAergic modulation during cognitive activity. (C) 2014 Elsevier B.V. All rights reserved.Publication Metadata only Long distance gamma (28-48 Hz) coherence decreases under cognitive load in drug free euthymic patients with bipolar disorder(Wiley-Blackwell Publishing, Inc, Commerce Place, 350 Main St, Malden 02148, Ma USA, 2010-03) Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; Turp, Bilge; Oral, Esat Timuçin; BAŞAR, EROL; 140995; 204666; 25145; 22231; 142226Publication Metadata only Significant decrease of EEG alpha activity and alpha response in bipolar patients(Wiley-Blackwell Publishing, Inc, Commerce Place, 350 Main St, Malden 02148, Ma USA, 2010-03) Güntekin, Bahar; Atagün, Murat İlhan; Oral, Esat Timuçin; Özerdem, Ayşegül; BAŞAR, EROL; 142226; 204666; 25145; 22231; 140995Publication Metadata only Significant decrease of EEG alpha activity and visual-evoked alpha response in bipolar patients(Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2010-09) Güntekin, Bahar; Atagün, Murat İlhan; Tülay, Elif; Özerdem, Ayşegül; BAŞAR, EROL; Erol Başar 142226; 204666; 25145; 140995Publication Metadata only Significant Reduction of EEG Alpha Activity and Sensory Alpha Response in Bipolar Patients(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 USA, 2010-05-01) Güntekin, Bahar; Atagün, Murat İlhan; Özerdem, Ayşegül; BAŞAR, EROL; 142226; 204666; 25145; 140995Publication Metadata only Theta Oscillations Are Diminished In Medication-Free Euthymic Patients With Bipolar Disorder(Wiley-Blackwell, Commerce Place, 350 Main St, Malden 02148, Ma Usa, 2011-06) Özerdem, Ayşegül; Güntekin, Bahar; Atagün, Murat İlhan; BAŞAR, EROL; TR140995; TR204666; TR142226; TR25145