Person: BAŞAR, EROL
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BAŞAR
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Publication Metadata only Resting state Rolandic mu rhythms are related to activity of sympathetic component of autonomic nervous system in healthy humans(Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2016-05) Triggiani, Antonio Ivano; Valenzano, Anna; Del Percio, Claudio; Marzano, Nicola; Soricelli, Andrea; Petito, Annamaria; Bellomo, Antonello; Mundi, Ciro; Cibelli, Giuseppe; Babiloni, Claudio; BAŞAR, EROL; 142226We tested the hypothesis of a relationship between heart rate variability (HRV) and Rolandic mu rhythms in relaxed condition of resting state. Resting state eyes-closed electroencephalographic (EEG) and electrocardiographic (ECG) data were recorded (10-20 System) in 42 healthy adults. EEG rhythms of interest were high frequency alpha (10.5-13 Hz) and low-frequency beta (13-20 Hz), which are supposed to form Rolandic mu rhythms. Rolandic and occipital (control) EEG sources were estimated by LORETA software. Results showed a statistically significant (p < 0.05, corrected) negative correlation across all subjects between Rolandic cortical sources of low-frequency beta rhythms and the low-frequency band power (LF, 0.04-0.15 Hz) of tachogram spectrum as an index of HRV. The lower the amplitude of Rolandic sources of low-frequency beta rhythms (as a putative sign of activity of somatomotor cortex), the higher the LF band power of tachogram spectrum (as a putative sign of sympathetic activity). This effect was specific as there was neither a similar correlation between these EEG rhythms and high-frequency band power of tachogram spectrum (as a putative sign of parasympathetic vagal activity) neither between occipital sources of low-frequency beta rhythms (as a putative sign of activity of visual cortex) and LF band power of tachogram spectrum. These results suggest that Rolandic low frequency beta rhythms are related to sympathetic activity regulating heart rate, as a dynamic neurophysiologic oscillatory mechanism sub-serving the interaction between brain neural populations involved in somatomotor control and brain neural populations regulating ANS signals to heart for on-going homeostatic adaptations. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Brain-Body-Mind in the nebulous cartesian system: A holistic approach by oscillations(SPRINGER, 233 SPRING STREET, NEW YORK, NY 10013, UNITED STATES, 2011) BAŞAR, EROLPublication Metadata only Views of hayek, hebb, and heiisenberg:Toward an approach to brain functioning(2011) BAŞAR, EROLPurpose - The conceptual ideas of Hebb, Heisenberg, and Feynman are embedded in the framework Hayek's so-called New Psychology. The present survey tries to bridge these concepts. Methodology - A theoretical and empirical informed approach. Findings - The theory of D. O. Hebb opened the way to "Neurobiology of Learning" in the past century. The S-Matrix theory of Werner Heisenberg and the so-called Feynman Diagrams that consider everything in the path-history of particles opened up new avenues to predict production of elementary particles. This as Hayek proposed or assumed in his theoretical monograph The Sensory Order. Originality/value of paper - Besides Fuster and Edelman few (if any) currently practicing neuroscientists have any knowledge of or appreciation of Hayek's philosophical psychology.Publication Metadata only Reduced Visual Event-Related Delta Oscillatory Responses in Amnestic Mild Cognitive Impairment(Ios Press, Nieuwe Hemweg 6B, 1013 Bg Amsterdam, Netherlands, 2013) Yener, Görsev; Kurt, Pınar; Emek Savaş, Derya Durusu; Güntekin, Bahar; BAŞAR, EROL; 143760; 24351; 227002; 204666; 142226Mild cognitive impairment (MCI) is considered as a prodromal stage for Alzheimer's disease (AD) in the majority of cases. Event-related oscillations might be used for detection of cognitive deficits. Our group's earlier results showed diminished delta visual and auditory target oscillatory responses in AD, and we investigated whether this prevails for MCI. Eighteen MCI subjects and 18 age-matched healthy elderly controls were investigated. The maximum peak-to-peak amplitudes of oscillatory responses for each subject's averaged oscillatory target responses in delta, theta, and alpha frequency bands upon application of visual oddball paradigm were measured. Repeated measures of ANOVA was used to analyze four locations (frontal, central, parietal, occipital), at three coronal (left, midline, right) sites. Independent t tests were applied for post-hoc analyses. The oddball target delta response (0.5-3.0 Hz) was 26-32% lower in MCI than healthy controls over fronto-central-parietal regions [F(1.34) = 4.562, p = 0.04]. Without a group effect, theta oscillatory responses (4-7 Hz) showed significant differences in coronal electrodes indicating highest values over mid-electrode sites, and a anteriorposterior x coronal effect, being maximum at mid-central. Alpha frequency band analyses indicated no statistical differences. Peak-to-peak amplitudes of visual target delta oscillatory responses were lower in fronto-central-parietal regions in MCI than in healthy controls. This supports our earlier findings in AD, showing hypoactive delta fronto-central-parietal regions during cognitive tasks. These results indicate that event-related oscillations may detect early changes of brain dynamics in MCI, and deserves to be investigated as a candidate biomarker in further studies using multimodal techniques.Publication Unknown Selective Gamma Activation in Alzheimer, Bipolar Disease and Schizophrenia(Elsevier Science Inc, 360 Park Ave South, New York, Ny 10010-1710 Usa, 2011-05-01) Başar Eroğlu, Canan; Güntekin, Bahar; Özerdem, Ayşegül; Yener, Görsev; BAŞAR, EROL; 142226; 274866; 204666; 140995; 143760Publication Metadata only Disturbance In Long Distance Gamma Coherence In Bipolar Disorder(Pergamon-Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1Gb, England, 2010-08-16) Özerdem, Ayşegül; Güntekin, Bahar; Saatçı, Ertuğrul; Tunca, Zeliha; BAŞAR, EROL; TR140995; TR204666; TR10488; TR142226The aim of this study was to investigate long distance event-related gamma (28-48 Hz) coherence in mania before and after valproate monotherapy. Gamma coherence in response to visual oddball paradigm in ten medication-free, manic patients was studied before and after six weeks of valproate monotherapy in comparison to ten controls. Inter-hemispheric F(3)-F(4), C(3)-C(4), T(3)-T(4), T(5)-T(6), P(3)-P(4), O(1)-O(2) and intra-hemispheric F(3)-P(3), F(4)-P(4), F(3)-T(5), F(4)-T(6), F(3)-O(1), F(4)-O(2), C(3)-O(1), C(2)-O(4) electrode pairs were included in the analysis. Repeated measures ANOVA revealed a significant difference between groups with regard to pre-treatment coherence values (p: 0.018). The coherence to the target stimuli at the right fronto-temporal location was significantly reduced by 35.41% in the patients compared to controls (p: 0.003). Patients showed significantly lower pretreatment coherence values in response to non-target stimuli compared to controls at the right frontotemporal (28.51%, p: 0.004), right fronto-occipital (23.71%, p: 0.024), and right centro-occipital (25.69%, p: 0.029) locations. After six weeks of valproate monotherapy, manic symptoms improved significantly. Post-treatment change in target and non-target coherence values was statistically non-significant. EEG coherence is a measure of functional connectivity in the brain. Event-related gamma oscillations are essential for brain electrical activity. The results show that acute mania presents right sided long distance connectivity disturbance, thus pointing to the potential importance of measuring oscillatory responses in the search for consistent neurobiological markers in such a complicated condition as bipolar disorder. (C) 2010 Elsevier Inc. All rights reserved.Publication Metadata only Brain oscillations are highly influenced by gender differences(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2007-09) Güntekin, Bahar; BAŞAR, EROL; TR204666; TR142226There are few studies describing gender differences in event related oscillations (EROS). In the present report we demonstrate that gender differences are apparent in EROS even during simple visual stimulation, possibly activating very basic sensory networks. The data of 32 (16 males) healthy subjects were recorded from thirteen different scalp locations (F-3, F-4, C-z, C-3, C-4, T-3, T-4, T-5, T-6, P-3, P-4, O-1, O-2). Analysis was performed in the delta (0.5-3.5 Hz), theta (5-8.5 Hz), alpha (9-13 Hz), beta (15-24 Hz), and gamma (28-48 Hz) frequency ranges. The results showed that the maximum peak-to-peak delta response amplitudes for women were significantly higher than for men over occipital, parietal, central and temporal electrode locations. There were also differentiations in the beta and gamma oscillatory responses. These gender differences were most pronounced over the electrode Site O-2, that is, over primary visual areas. It is suggested that this study might serve as a standard to investigate gender differences in electrophysiology. (c) 2007 Elsevier B.V All rights reserved.Publication Metadata only Facial Affect Manifested By Multiple Oscillations(Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2009-01) Güntekin, Bahar; BAŞAR, EROL; TR204666; TR142226The present study describes electrophysiological differentiation of "Facial Expressions" by using the method of event-related oscillations (EROS). These measures were used to assess electrical manifestations of emotional expressions of 20 healthy subjects exposed to neutral, angry, and happy" faces. The present study extended previous analysis to frequency windows of delta (0.5-3.5 Hz) and theta (5-8.5 Hz) oscillations. No significant differences among responses to various face expression stimuli were observed, however, topological differences in response to all facial expressions were found. Delta oscillatory responses in the parietal-temporal-occipital locations were larger than the frontal and central locations, whereas theta oscillatory responses in the right temporal-occipital electrodes were larger than the right central electrodes. Assessment of topologically distributed multiple oscillations opens a new avenue for understanding of the electrophysiology of recognition of "faces" and "facial expressions". (c) 2008 Elsevier B.V. All rights reserved.Publication Metadata only Reduced long distance gamma (28-48 Hz) coherence in euthymic patients with bipolar disorder(Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2011-08) Özerdem, Ayşegül; Güntekin, Bahar; Atagün, İlhan; Turp, Bilge; BAŞAR, EROL; TR142226; TR25145; TR204666; TR140995Background: EEG coherence represents the brain's functional connectivity. Synchronous neural gamma oscillations are critical for cortico-cortical communication and large-scale integration of distributed sets of neurons. We investigated long distance gamma (28-48 Hz) coherence in bipolar disorder. Methods: Sensory evoked coherence (EC) and event related coherence (ERC) values for the gamma frequency band during simple light stimulation and visual odd-ball paradigm was assessed in 20 drug-free euthymic bipolar patients in comparison to healthy controls. Groups were compared for the coherence values of the left (F(3)-T(3), F(3)-TP(2), F(3)-P(3), F(3)-O(1)) and right (F(4)-T(4), F(4)-TP(8), F(4)-P(4), F(4)-O(2)) intra-hemispheric electrode pairs by means of a repeated measure analysis of variance (ANOVA) and t-tests. Results: Patients showed significantly lower gamma coherence values in response to target stimuli than the healthy controls between left and right fronto-temporal, as well as between frontal and temporo-parietal electrode pairs. Coherence values for the non-target stimuli were significantly lower in the patients than the healthy controls between frontal and temporo-parietal regions on both right and left sides. EP coherence values did not differ significantly between the groups. Limitations: A relatively small sample size is the major limitation of the study. Conclusions: Bipolar patients present disturbance in functional long-range connectivity between the frontal and temporal as well as temporo-parietal brain structures during a cognitive paradigm requiring attention and immediate recall. The location of the connectivity disturbance corresponds to the underlying neurobiology of executive function, memory and attention impairments in bipolar disorder and raises the question of whether gamma coherence reduction may be a candidate biomarker for bipolar disorder. (C) 2011 Elsevier B.V. All rights reserved.Publication Metadata only Emotional Face Expressions are Differentiated With Brain Oscillations(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2007-04) Güntekin, Bahar; BAŞAR, EROL; TR204666; TR142226The differentiation of "facial expressions" is a process of higher mental activity, which has considerable applications in "psychology of moods and emotions". We applied the approach of event-related oscillations (EROs) to investigate the modulation of electrical manifestations related to emotional expression in EEG recordings of 20 healthy subjects. EROs of "neutral, angry and happy" faces in 13 electrical recordings sites (F-3, F-4, C-z, C-3, C-4, T-3, T-4, T-5, T-6, P-3, P-4, O-1, O-2) were analyzed. Following the recording session, the subjects were asked to express the degree of their emotional involvement (valence and arousal) using the Self-Assessment Manikin ratings. Amplitude frequency characteristics (AFCs) were used to determine the frequencies of interest and the ranges for digital pass-band filtering applied accordingly. Consecutively, peak to peak amplitude measures of oscillatory responses were computed for the selected frequency bands and for the differentiation of the different stimuli. A differentiation between angry and happy facial expressions was observed especially in the alpha (9-13 Hz) and beta (15-24 Hz) frequencies, however, only when selecting stimuli with high mood involvement. Therefore, these frequency bands are the main focus of this report. The amplitudes of the alpha responses upon angry face stimulation were significantly higher than upon presentation of the happy faces at posterior locations. At F3, C, and C3, beta responses upon angry face stimulation were significantly higher in amplitude compared with the happy face stimulation. It is discussed that the frontal theta response is highly increased in comparison to all theta responses also encountered in studies of face recognition: During observation of facial expression, the occipital theta is much higher. We conclude and emphasize that the analysis of brain oscillatory responses distributed over the scalp in combination with subjective ratings of emotional impact of stimuli provide a good basis for analysing the influence of emotional information processing in the brain. In congruence with others, the results support the phylogenetical viewpoint suggesting that angry face stimulations are faster and more ample in responding. Furthermore, frontal, temporal, parietal and occipital lobes seem to be involved in processing of facial expressions, as reflected in an ensemble of different frequency brain oscillatory responses distributed over the scalp. (c) 2006 Published by Elsevier B.V.