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Now showing 1 - 10 of 130
  • Publication
    Brain's Alpha, Beta, Gamma, delta, and theta oscillations in neuropsychiatric diseases: Proposal for biomarker strategies
    (2013) Başar Eroğlu, Canan; Güntekin, Bahar; Gülmen Yener, Görsev; BAŞAR, EROL
    Brain oscillations have gained tremendous importance in neuroscience during recent decades as functional building blocks of sensory-cognitive processes. Research also shows that event-related oscillations (EROs) in "alpha," "beta," "gamma," "delta," and "theta" frequency windows are highly modified in pathological brains, especially in patients with cognitive impairment. The strategies and methods applied in the present report reflect the innate organization of the brain: "the whole brain work." The present paper is an account of methods such as evoked/event-related spectra, evoked/ERDs, coherence analysis, and phase-locking. The report does not aim to cover all strategies related to the systems theory applied in brain research literature. However, the essential methods and concepts are applied in several examples from Alzheimer's disease (AD), schizophrenia, and bipolar disorder (BD), and such examples lead to fundamental statements in the search for neurophysiological biomarkers in cognitive impairment. An overview of the results clearly demonstrates that it is obligatory to apply the method of oscillations in multiple electroencephalogram frequency windows in search of functional biomarkers and to detect the effects of drug applications. Again, according to the summary of results in AD patients and BD patients, multiple oscillations and selectively distributed recordings must be analyzed and should include multiple locations. Selective connectivity between selectively distributed neural networks has to be computed by means of spatial coherence. Therefore, by designing a strategy for diagnostics, the differential diagnostics, and application of (preventive) drugs, neurophysiological information should be analyzed within a framework including multiple methods and multiple frequency bands. The application of drugs/neurotransmitters gains a new impact with the analysis of oscillations and coherences. A more clear and differentiated analysis of drug effects can be attained in comparison to the application of the conventional wide-band evoked potential and event-related potential applications.
  • Publication
    Brain oscillations in neuropsychiatric disease
    (2013-09) BAŞAR, EROL
    The term “brain (or neural) oscillations” refers to the rhythmic and/or repetitive electrical activity generated spontaneously and in response to stimuli by neural tissue in the central nervous system. The importance of brain oscillations in sensory-cognitive processes has become increasingly evident. It has also become clear that event-related oscillations are modified in many types of neuropathology, in particular in cognitive impairment. This review discusses methods such as evoked/event-related oscillations and spectra, coherence analysis, and phase locking. It gives examples of applications of essential methods and concepts in bipolar disorder that provide a basis for fundamental notions regarding neurophysiologic biomarkers in cognitive impairment. The take-home message is that in the development of diagnostic and pharmacotherapeutic strategies, neurophysiologic data should be analyzed in a framework that uses a multiplicity of methods and frequency bands.
  • Publication
    Prolongation Of Alpha Oscillations İn Auditory Oddball Paradigm
    (Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2009-03) Öniz, Adile; BAŞAR, EROL; TR59951; TR142226
    Although an important component of the P300 target response is the "prolonged alpha response". no relevant analysis is found in the literature. The present study emphasizes the relevance of prolongation of alpha responses in auditory oddball paradigm. Two types of stimuli were applied to twenty subjects. As standard stimuli 80 dB-1500 Hz tones and the target stimuli 80 dB-1600 Hz tones were used. The prolongations of alpha responses were measured in 13 recording sites in the frequency range of 8-13 Hz. At the Cz recording site, the time period for reaching one third (duration of prolongation) of its peak-to-peak amplitude (1/3 latency) of alpha response to target was 446 ms. The prolongation of nontarget stimuli was 277 ms. Thus, the alpha response to target was significantly more prolonged than the alpha response to nontarget stimuli. Similarly, at C3, the alpha response to target stimuli was prolonged to 373 ms. The alpha response to nontarget stimuli was prolonged to 284 ms. The target alpha response was more prolonged in comparison to the non-target alpha results. The alpha response to target stimuli (431 ms) was also more prolonged in comparison with the alpha response upon non-target stimuli (266 ms) at the C4 recording site. The results indicate that the alpha responses are prolonged under a certain level of cognitive load and working memory. Alpha prolongation is a significant component of P300 responses. It can be Suggested that the cognitive load dependency of alpha responses upon the targets could be related to working memory. (C) 2008 Elsevier B.V. All rights reserved.
  • PublicationOpen Access
    How is the brain working? Research on brain oscillations and connectivities in a new "Take-Off" state
    (Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2016-05) Düzgün, Aysel; BAŞAR, EROL; 142226
    The present report is a trial to survey analysis and applications of brain oscillations in cognitive impairment for opening the way to a new take off in research on brain oscillation. Although the number of papers related to brain oscillations rapidly increases, it is important to indicate the common principles governing the functioning of brain oscillations in the brain and body. Research scientists need a global view on the types of analysis, applications and existing oscillations. Further, scientists dealing with brain oscillations must have some knowledge from theoretical physics, system theory, and also general philosophy. The neuroscientists working on brain oscillations can mentally integrate several papers in the present report, and try to discover new avenues to augment knowledge on brain functions. A new take off in the search of brain oscillations indicates the strong need to survey this brunch of neuroscience in a broad panoply of science. (C) 2016 The Authors. Published by Elsevier B.V.
  • Publication
    Review of Delta, Theta, Alpha, Beta, and Gamma response oscillations in neuropsychiatric disorders
    (2013) Güntekin, Bahar; BAŞAR, EROL
    Method and concepts of brain oscillations pervade the neuroscience literature, especially in cognitive processes. Electrophysiological changes in patients with cognitive impairment will provide fundamental knowledge, not only for clinical studies but also, in turn, for understanding cognitive processes in healthy subjects. This review includes description of brain oscillations in schizophrenia, bipolar disorder, mild cognitive impairment, Alzheimer's disease, and attention deficit hyperactivity disorder. The reviewed publications include several methodological approaches: analysis of spontaneous electroencephalogram (EEG) spectra, evoked oscillations, event-related oscillations, and coherences both in spontaneous EEG and event-related oscillations. The review clearly shows that, in cognitive impairment, fundamental changes are observed in all diseases under study. Accordingly, oscillations can most probably be used as biomarkers in clinical studies. The conclusions of this review include several remarks indicating the nature of brain oscillations, their application to cognitive processes, and the usefulness of recording brain oscillations in memory loss, attention deficit, and learning.
  • PublicationOpen Access
    The City Experience with Location-Based Media: An Examination Through Cognitive Maps
    (Konya Technical University, 2021) IAVARONE, AYŞENUR HİLAL; HASGÜL, ESİN; BAŞAR, EROL
    Purpose The physical space has been an important value for supporting human experience. With the development of mobile devices and location-based media, these technologies have been increasingly present in our virtual spatial experience and the experience of physical city has been changed permanently. Accordingly, this paper aims to discuss the experience potential of urban space with location-based technologies. Design/Methodology/Approach The research structure of this study is based on the literature of location-based media and 'Space of flow' theory. Within the methodology, a workshop is conducted to review the cognitive mappings of the virtual city experience. The workshop is structured through two segments: Documenting the spatial experience revealed using location-based media made by cognitive mappings and testing participants' direct experiences within structured questionnaire-based interviews and finally, interpretating of the obtained data. Findings This paper provides an experiential examination of the relationship between the usage of the degree of location-based media and cognitive experience. Findings point out that experience may differ depending on the media interface used and it is controversial comparing with the physical space experience with its multiple relationships. Research Limitations/Implications The research subject had been exemplified with limited location-based media in a specific location. Originality/Value The proposed method of examining the degree of spatial experience by the location-based media linking with interviews determines the originality of the study. There are also limited studies on the topic of location-based media by focusing on the users' cognitive maps.
  • Publication
    A short review of alpha activity In cognitive processes and in cognitive impairment
    (Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2012-10) Güntekin, Bahar; BAŞAR, EROL; TR142226; TR204666
    Aim of the report: In the companion report (Basar, this volume), the physiological fundaments of alpha activity in integrative brain function are described. The present report is a review of the significant role of alpha activity in memory and cognitive processes in healthy subjects, and in cognitive impairment. The role of neurotransmitters is also described, briefly, in this context. Towards an understanding of brain alpha: Despite numerous experimental studies, it is indicated that the presented results are only appropriate to establish an ensemble of reasonings and suggestions for analyzing "alphas" in the whole brain. In turn, in the near future, these reasonings and suggestions may serve (or are indispensable to serve) as fundaments of more general and tenable hypotheses on the genesis and function of "alphas". (C) 2012 Elsevier B.V. All rights
  • Publication
    Affective pictures processing is reflected by an increased long-distance EEG connectivity
    (Springer, Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands, 2017-08) Güntekin, Bahar; Femir, Banu; Turp Gölbaşı, Bilge; Tülay, Elif; BAŞAR, EROL; 204666; 142226
    Analysis of affective picture processing by means of EEG has invaded the literature. The methodology of event-related EEG coherence is one of the essential methods used to analyze functional connectivity. The aims of the present study are to find out the long range EEG connectivity changes in perception of different affective pictures and analyze gender differences in these long range connected networks. EEGs of 28 healthy subjects (14 female) were recorded at 32 locations. The participants passively viewed emotional pictures (IAPS, unpleasant, pleasant, neutral). The long-distance intra-hemispheric event-related coherence was analyzed for delta (1-3.5 Hz), theta (4-7.5 Hz), and alpha (8-13 Hz) frequency ranges for F-3-T-7, F-4-T-8, F-3-TP7, F-4-TP8, F-3-P-3, F-4-P-4, F-3-O-1, F-4-O-2, C-3-O-1, C-4-O-2 electrode pairs. Unpleasant pictures elicited significantly higher delta coherence values than neutral pictures (p < 0.05), over fronto-parietal, fronto-occipital, and centro-occipital electrode pairs. Furthermore, unpleasant pictures elicited higher theta coherence values than pleasant (p < 0.05) and neutral pictures (p < 0.05). The present study showed that female subjects had higher delta (p < 0.05) and theta (p < 0.05) coherence values than male subjects. This difference was observed more for emotional pictures than for neutral pictures. This study showed that the brain connectivity was higher during emotional pictures than neutral pictures. Females had higher connectivity between different parts of the brain than males during emotional processes. According to these results, we may comment that increased valence and arousal caused increased brain activity. It seems that not just single sources but functional networks were also activated during perception of emotional pictures.
  • PublicationOpen Access
    The brain as a working syncytium and memory as a continuum in a hyper timespace: Oscillations lead to a new model
    (Elsevier Science Bv, Po Box 211, 1000 AE Amsterdam, Netherlands, 2016-05) Düzgün, Aysel; BAŞAR, EROL; 142226
    The aim of this study is threefold: (1) we propose a new framework describing the neurophysiologic functioning and cognitive processing of neural populations, and we extend the neuron doctrine to the physiology of neural assemblies. (2) The extension from neurons to neural populations implies that the brain, with its connectivity, should be considered a working syncytium, which extends Brodmann mapping to the CLAIR model, which includes oscillatory components and their connectivity. (3) In such a working syncytium, a new description of "memory" is needed in the broad time-space continuum, which embraces all memory states. This will be called "hypermemory." (C) 2016 The Authors. Published by Elsevier B.V.
  • Publication
    Bergson's Intuition and Memory in View of NeuroQuantology
    (Anka Publısher, 116-11 Sok No.10 K 2 D 2, Bornova, Izmir 35050, Turkey, 2009) Güntekin, Bahar; BAŞAR, EROL; TR142226; TR204666
    This essay describes the concept of great philosopher Henri Bergson, related to episodic memory, intuition and duration. Further, the relation of "quantum theory" to Bergson's philosophy is shortly described. We discuss the importance of Bergson's concepts to "Quantum Methodology" and modern science.