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- YayınSadece MetadataPrinciples of Oscillatory Brain Dynamics and a Treatise of recognition of Faces and Facial Expressions(ELSEVIER SCIENCE BV, SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2006) Başar, Erol; Güntekin, Bahar; Öniz, Adile; TR142226; TR204666; TR59951The research of event-related oscillations is one of fast-growing fields in neuroscience. In this study, a theory of the "whole-brain-work," which can be useful for functional interpretation of brain oscillations, is presented together with its application to recognition of faces and facial expressions. Following results are summarized: (1) Mechanisms leading to the perception of the grandmother picture are manifested with parallel activations of neural assemblies in different cortical locations and as superposition of delta, theta, alpha, beta, and gamma oscillations. Known and anonymous faces can be differentiated by means of oscillatory brain dynamics. Percepts cannot be localized in a given specific region. The differentiation of facial expression induces significant change in alpha and theta oscillation. (2) While the importance of fMRI in object recognition is clear, this method has low temporal resolution. Our results shows that multiple brain oscillations clearly differentiate the known and unknown faces with varied degrees of selective-responsiveness in a short time window between 0 and 800 ins, thus completing and implementing the analysis of percepts in the dynamic window and indicating a broader distribution at the cortex. (3) The presented evidence of selectively distributed multiple oscillations for differentiation of facial percepts is in conceptual accordance with the "selectively distributed processing" in neurocognitive networks of Goldman-Rakic, Fuster, and of Mesulam. The large-scale approach of several investigators is also confirmed with the new results. On facial stimuli, a given location can show a considerable selected activation, but the formation of percepts is manifested by multiple oscillations with differentiated weight in large neural populations. (4) The most important feature of the comparison of percepts of grandmother and anonymous faces is the existence of a variety of significant differences in delta, theta, alpha, beta, and gamma responses between the anonymous and grandmother faces in frontal, central, parietal, temporal, and occipital sites. (5) The brain response is a construct in a multi-dimensional state manifested by amplitudes of oscillatory responses, topological coordinates, and changes in the time axis following presentation of the percepts including delays and prolongations, coherence between locations. Only a new metrics embracing all these parameters can be representative for dynamics of functionality in the brain. The conceptual aspects of this new scope are explained in the presented theory.
- YayınSadece MetadataLung model parameter estimation by unscented Kalman filter(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2007) Saatçı, Esra; Akan, Aydın; TR2918; TR112197Dynamic nonlinear models are the best choice to analyze respiratory systems and to describe system mechanics. In this work, Unscented Kalman Filtering (UKF) was used to estimate the dynamic nonlinear model parameters of the lung model by using the measured airway flow, mask pressure and integrated lung volume. Artificially generated data and the data from Chronic Obstructive Pulmonary Diseased (COPD) patients were analyzed by the proposed model and the proposed UKF algorithm. Simulation results for both cases demonstrated that UKF is a promising estimation method for the respiratory system analysis.
- YayınSadece MetadataPolyamines in tea processing(TAYLOR & FRANCIS LTD, 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND, 2007) Palavan Ünsal, Narçin; Arısan, Elif Damla; Terzioğlu, Salih; TR6125; TR113920; TR2496The distribution of dietary polyamines, putrescine, spermidine and spermine, was determined during processing of Camellia sinensis. Black tea manufacture is carried by a series of processes on fresh tea leaves involving withering, rolling, fermentation, drying and sieving. The aim of this research was to determine the effect of tea processing on the polyamine content in relation with antioxidant enzymes, superoxide dismutase, lipid peroxidase and glutathione peroxidase. Before processing, the spermine content was much higher than the putrescine and spermidine content in green tea leaves. Spermine was significantly decreased during processing while the putrescine and spermine contents increased during withered and rolling and decreased in the following stages. The superoxide dismutase activity increased at the withering stage and declined during processing. The transcript level of the polyamine biosynthesis-responsible enzyme ornithine decarboxylase was reduced during each processing step. This study reveals the importance of protection of nutritional compounds that are essential for health during the manufacturing process.
- YayınSadece MetadataA breakthrough in neuroscience needs a "Nebulous Cartesian System" Oscillations, quantum dynamics and chaos in the brain and vegetative system(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2007-04) Başar, Erol; Güntekin, Bahar; TR142226; TR204666The Cartesian System is a fundamental conceptual and analytical framework related and interwoven with the concept and applications of Newtonian Dynamics. In order to analyze quantum processes physicist moved to a Probabilistic Cartesian System in which the causality principle became a probabilistic one. This means the trajectories of particles (obeying quantum rules) can be described only with the concept of cloudy wave packets. The approach to the brain-body-mind problem requires more than the prerequisite of modem physics and quantum dynamics. In the analysis of the brain-body-mind construct we have to include uncertain causalities and consequently multiple uncertain causalities. These multiple causalities originate from (1) nonlinear properties of the vegetative system (e.g. irregularities in biochemical transmitters, cardiac output, turbulences in the vascular system, respiratory apnea, nonlinear oscillatory interactions in peristalsis); (2) nonlinear behavior of the neuronal electricity (e.g. chaotic behavior measured by EEG), (3) genetic modulations, and (4) additional to these physiological entities nonlinear properties of physical processes in the body. The brain shows deterministic chaos with a correlation dimension of approx. D-2=6, the smooth muscles approx. D-2=3. According to these facts we propose a hyper-probabilistic approach or a hyper-probabilistic Cartesian System to describe and analyze the processes in the brain-body-mind system. If we add aspects as our sentiments, emotions and creativity to this construct, better said to this already hyper-probabilistic construct, this "New Cartesian System" is more than hyper-probabilistic, it is a nebulous system, we can predict the future only in a nebulous way; however, despite this chain of reasoning we can still provide predictions on brain-body-mind incorporations. We tentatively assume that the processes or mechanisms of the brain-body-mind system can be analyzed and predicted similar to the metaphor of '' finding the walking path in a cloudy or foggy day". This is meant by stating "The Nebulous Cartesian System" (NCS). Descartes, at his time undertaking his genius step, did not possess the knowledge of today's physiology and modem physics; we think that the time has come to consider such a New Cartesian System. To deal with this, we propose the utilization of the Heisenberg S-Matrix and a modified version of the Feynman Diagrams which we call "Brain Feynman Diagrams". Another metaphor to consider within the oscillatory approach of the NCS is the "string theory". We also emphasize that fundamental steps should be undertaken in order to create the own dynamical framework of the brain-body-mind incorporation; suggestions or metaphors from physics and mathematics are useful; however, the grammar of the brains intrinsic language must be understood with the help of a new biologically founded, adaptive-probabilistic Cartesian system. This new Cartesian System will undergo mutations and transcend to the philosophy of Henri Bergson in parallel to the Evolution theory of Charles Darwin to open gateways for approaching the brain-body-mind problem. (c) 2006 Published by Elsevier B.V.
- YayınSadece MetadataEmotional 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.
- YayınSadece MetadataBrain Oscillations Differentiate the Picture of One's Own Grandmother(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2007-04) Başar, Erol; Özgören, Murat; Öniz, Adile; Schmiedt, Christina; Başar-Eroğlu, Canan; TR142226; TR143075; TR59951; TR186954The present report introduces, as a first study, the concept and methods of oscillatory brain dynamics to analyze well-known (familiar) and unfamiliar face processing in the 800 ms following a face presentation. We analyzed event-related oscillations in young, healthy subjects (N=26) by using three types of stimulation: (1) a simple light signal, (2) the picture of the face of an anonymous elderly lady and (3) the picture of the subjects' own grandmother. We found a number of significant peak to peak amplitude measures in all frequency bands in the time period of 0-500 ms, allowing a differentiation between perception of the subjects' own grandmother, the unknown elderly face and the light stimulation. The results showed increased event-related oscillatory responses elicited by the unknown face compared to the known grandmother a) in the theta responses (4-8 Hz) at T-6 (46%), b) in the gamma (28-48 Hz) responses at C-z (22%) and C-3 (38%) and c) in the beta responses at F-4 (46%), C-z (47%) and P-3 (105%). In contrast, the subjects' own grandmother elicited 20% increased fast theta (6-8 Hz) oscillations at F-4 compared to the unknown face. Delta responses dissociated face from simple light processing, as reflected in the observation of approx. 50% higher amplitudes at the occipital compared to the frontal locations during face perception. We conclude that the described multiple brain oscillations clearly differentiate the known and unknown faces with varied degrees of selective-responsiveness in a short time window between 0 and 800 ms. Furthermore, the results are in conceptual accordance with the "selectively distributed processing" hypothesis. (c) 2006 Published by Elsevier B.V.
- YayınSadece MetadataBrain 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.
- YayınSadece MetadataGender 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.
- YayınSadece MetadataRESPIRATORY PARAMETER ESTIMATION IN LINEAR LUNG MODELS(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2008) Saatçı, Esra; Akan, Aydın; TR2918; TR112197If the respiratory system Is represented as a one compartment model composed of linear electrical elements, the Minimum Variance Unbiased Estimation (MVUE) Is the optimum statistical method to estimate the model parameters. Two well known linear models, RIC and Viscoelastic models were chosen and their parameters were estimated by MVUE. Synthetic data simulations showed that minimum 100Hz sampling rate is required in order to have minimum variance. Estimation of lung inertance and viscoelastic tissue compliance parameters resulted in very large estimation variance, whereas the rest of the parameters were estimated successfully. Both parameter values and estimator variances have their own characterization in terms of patient discrimination for diagnostic purposes.
- YayınSadece MetadataDrug/nondrug classification with consensual self-organising map and self-organising global ranking algorithms(2008) Pehlivanlı, Ayça C.; Ersoy, Okan K.; ibrikçi, TurgayIn this paper, a special consensual approach is discussed for separating the druglike compounds from the non-druglike compounds. It involves a group decision to produce a consensus of multiple classification results obtained with a single classification algorithm. The individual results are obtained with either the Self Organising Global Ranking (SOGR) or Self Organising Map (SOM). The main difference between the proposed algorithm and SOM is the neighbourhood concept. The constructed consensual model has a preprocessing unit which consists of transformation of input patterns by random matrices and median filtering to generate independent errors for a single type of classifier, and a postprocessing unit for consensus. The confirmed drugs were classified with a consensual accuracy of 90.63% while nondrugs resulted in 80.44% accuracy. The SOGR results were better than the SOM algorithm results.
- YayınSadece MetadataBrain Oscillations Evoked by the Face of a Loved Person(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2008-06-12) Başar, Erol; Schmiedt-Fehr, Christina; Öniz, Adile; Başar Eroğlu, Canan; TR59951; TR142226Previous studies have shown a close interrelation between emotional processing and memory processes using facial stimuli and applying the concept of oscillatory brain dynamics. Amending prior findings the influence of neural correlates related to the emotional state termed "romantic love" was investigated. Specifically, the effect of feelings of love on face perception was of interest. Pictures of a "loved person" were presented to female subjects and the elicited responses were compared with responses to pictures showing faces of a "known and appreciated person" or an "unknown person" during EEG recordings (n=20 females). As a control condition light stimulation was employed. The sequence of faces shown was presented in random and block-design. EEG data was analyzed considering maximum amplitudes and topographical differences within the conventional frequency bands of delta, theta, alpha, beta and gamma. Differences between light and face stimuli were found in the delta and theta bands and differences between the face types and the two designs were found in the delta band. The delta response to the picture of the "loved person" showed significantly higher amplitude values, not only in comparison with the "unknown person", but also with the picture of the "appreciated person". Frontal lobes appear to react to different types of facial stimuli with specific increases in delta responses. The difference between the response to the "loved person" and of the "known and appreciated person" reflects the component of the emotion denoted as love. The findings and their interpretations are discussed within the framework of event-related oscillations and complex stimulus processing emphasizing the concept of dynamic localization. (C) 2008 Published by Elsevier B.V.
- YayınSadece MetadataDecrease of evoked delta, theta and alpha coherences in Alzheimer patients during a visual oddball paradigm(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2008-10-15) Güntekin, Bahar; Saatçı, Ertuğrul; Yener, Görsev; TR143760; TR204666; TR10488In this study event related coherence of patients with Alzheimer type of dementia (AD) was analyzed by using a visual oddball paradigm as stimuli. A total of 21 mild probable AD subjects (10 untreated, 11 treated) were compared with a group of 19 healthy controls. The members of the groups had their EEG recorded from 12 electrodes by means of a visual oddball paradigm. The evoked coherence was analyzed for delta (1-3.5 Hz), theta (4-7 Hz) and alpha (8-13 Hz) frequency ranges for 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 long range intra-hemi spheric (F(3)-P(3), F(4)-P(4), F(3)-T(5), F(4)-T(6), F(3)-O(1), F(4)-O(2)) electrode pairs. The control group showed higher values of evoked coherence in "delta", "theta" and "alpha" bands in the left fronto-parietal electrode pairs in comparison with the untreated AD group (p < 0.01 for all frequency bands). Furthermore, the control group showed higher values of evoked coherence in the left fronto-parietal electrode pair in theta frequency band (p < 0.01) and higher values of evoked coherence in the right fronto-parietal electrode pair in delta band (p < 0.01) when compared to treated AD group. The only significant difference between the treated and untreated AD groups was in the alpha band. The treated AD group showed higher values of evoked coherence at the left fronto-parietal pair in alpha band in comparison to the untreated AD group (p < 0.01). During a working memory process the coherence in the left fronto-parietal electrode pair (F(3)-P(3)) of AD patients is significantly decreased, thus indicating reduced connectivity between frontal and parietal sites. (c) 2008 Elsevier B.V. All rights reserved.
- YayınSadece MetadataA review of brain oscillations in cognitive disorders and the role of neurotransmitters(ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS, 2008-10-15) Başar, Erol; Güntekin, Bahar; TR142226; TR204666The analysis of the functional correlates of "brain oscillations" has become an important branch of neuroscience. Although research on the functional correlates of brain oscillation has progressed to a high level, studies on cognitive disorders are rare and mainly limited to schizophrenia patients. The present review includes the results of the changes in brain oscillations in patients with Alzheimer's, schizophrenia, bipolar disorders, mild cognitive impairment, attention-deficit hyperactivity disorder (ADHD), alcoholism and those with genetic disorders. Furthermore, the effects of pharmaca and the influence of neurotransmitters in patients with cognitive disorders are also reviewed. Following the review, a short synopsis is given related to the analysis of brain oscillations. (c) 2008 Elsevier B.V. All rights reserved.
- YayınSadece MetadataFacial 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.
- YayınSadece MetadataCharacterization of GH-1 Mutations in Children with Isolated Growth Hormone Deficiency in the Turkish Population(FREUND PUBLISHING HOUSE LTD, PO BOX 35010, TEL AVIV 61350, ISRAEL, 2009-10) Çoker, Ajda; Çetinkaya, Ergun; Dündar, Bumin; Şıklar, Zeynep; Büyükgebiz, Atilla; Arman, Ahmet; TR125860; TR1603; TR173248Isolated growth hormone deficiency (IGHD) is defined as a medical condition associated with growth failure due to insufficient production of growth hormone (GH) or lack of growth hormone action. It occurs with an incidence of between 1/4,000 and 1/10,000 live births. Most cases are sporadic and idiopathic but 5-30% of growth hormone deficiency (GHD) has genetic etiology. Mutations in the GH encoding gene (GH-1) have been detected in patients with IGHD. The purpose of this study was to characterize mutations of the GH-1 gene in children with IGHD in the Turkish population. We found four missense mutations (E33G, N47D, T-24A and A13S), one nonsense mutation (W-7X), one insertion and two deletions in nine patients out of seventy-five patients with IGHD. The missense mutation A13S, GAAA insertion at intron 1 (+178A), and the deletions of +83C in intron I and Delta F166 in exon 5 are novel mutations.
- YayınSadece MetadataAdsorption Of Isoniazid Onto Sepiolite-Palygorskite Group Of Clays: An IR Study(Pergamon-Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington, Oxford Ox5 1Gb, England, 2010-04) Akyüz, Sevim; Akyüz, Tanıl; Akalın, Elif; TR10127; TR111424; TR46357The adsorption of isoniazid (INH) on sepiolite, loughlinite (natural Na-sepiolite) and palygorskite from Anatolia was investigated by FT-IR spectroscopy. Experimental results indicated that INH molecules, adsorbed on sepiolite-palygorskite group of clays, are coordinated to surface hydroxyls by H-bonding interaction through the pyridine ring nitrogen lone pairs. Moreover, some of the adsorbed INH molecules may enter the interior channels of the sepiolite-palygorskite structure and involve H-bonding interaction with zeolitic water. Some intensity and frequency changes in the OH stretching band of surface hydroxyls (Si-OH) of the INH-treated sepiolite and loughlinite were observed. However, this band is found to be less affected by the adsorption of isoniazid in the case of palygorskite, probably because the surface Si-OH groups in palygorskite appear to be less abundant than in sepiolite or loughlinite. (C) 2010 Elsevier B.V. All rights reserved.
- YayınAçık ErişimA New Interpretation Of P300 Responses Upon Analysis Of Coherences(Springer, Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands, 2010-06) Güntekin, Bahar; Başar, Erol; TR142226; TR204666Previous studies on cognitive dynamics showed that oscillatory responses of P300 are composed of mainly delta and theta responses. In the present study, for the first time, the long-distance intra-hemispheric event related coherence (auditory oddball paradigm) and evoked coherence (simple sound) were compared in order to evaluate the effects of cognitive tasks on the long-distance coherences. Seventeen healthy subjects (8 female, 9 male) were included in the study. The coherence was analyzed for delta (1-3.5 Hz), theta (4-7.5 Hz) and alpha (8-13 Hz) frequency ranges for (F(3)-P(3), F(4)-P(4), F(3)-T(7), F(4)-T(8), F(3)-O(1,) F(4)-O(2)) electrode pairs. The coherence to target responses were higher than the non-target and simple auditory response coherence. This difference is significant for the delta coherence for both hemispheres and for theta coherences over the left hemisphere. The highest coherences were recorded at fronto-temporal locations for all frequency bands (delta, theta, alpha). Furthermore, fronto-parietal coherences were higher than the fronto-occipital coherences for all frequency bands (delta, theta, alpha).These results show that the fronto-temporal and fronto-parietal connections are most relevant for the identification of the target signal. This analysis open the way for a new interpretation of dynamic localization results during cognitive tasks.
- YayınSadece MetadataEvent-Related Beta Oscillations Are Affected By Emotional Eliciting Stimuli(Elsevier Ireland Ltd, Elsevier House, Brookvale Plaza, East Park Shannon, Co, Clare, 00000, Ireland, 2010-10-15) Güntekin, Bahar; Başar, Erol; TR204666; TR142226According to previous results, negative emotional facial expressions elicit oscillatory beta responses The present study analyzes event-related beta oscillations upon presentation of International Affective Picture System (IAPS) and aims to show whether behavior of beta in response to negative IAPS pictures also have similar dynamics IAPS pictures (unpleasant, pleasant, and neutral) were presented as a block and random passive viewing to 14 healthy subjects (8 male). Only with pictures with similar luminance level were selected as stimuli. Event-Related Potentials (ERPs) were recorded from 30 different scalp locations, and adaptive digital filtering was used for analysis in different frequency windows. The maximum peak-to-peak amplitudes were measured for each subject's averaged beta responses (15-30 Hz) in the 0 and 300 ms time window. Beta responses were significantly higher for unpleasant pictures than for pleasant and neutral pictures (average 50%). Beta responses were significantly higher for unpleasant than for pleasant pictures over frontal, central and parietal electrode sides (p < 0.05). Furthermore, beta responses were significantly higher for unpleasant than for neutral pictures over parietal and occipital electrodes (p < 0 04) In addition, the pleasant pictures elicited higher beta responses than neutral pictures over occipital electrode sites (p < 0 04) The results of the present study indicate that negative emotions are related to increased beta responses in humans, independent of stimulus types (facial expression or IAPS pictures) Accordingly, beta responses to negative emotions are possibly a common phenomenon The standardization of luminance in pictures may reduce divergences between results from different laboratories (C) 2010 Elsevier Ireland Ltd All rights reserved.
- YayınSadece MetadataEvoked And Event Related Coherence Of Alzheimer Patients Manifest Differentiation Of Sensory-Cognitive Networks(Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2010-10-21) Başar, Erol; Güntekin, Bahar; Tülay, Elif; Yener, Görsev G.; TR143760; TR142226; TR204666; TR142311In previous studies on Alzheimer's patients it was shown that, in frontal and parietal locations, delta and theta responses of AD patients were greatly reduced. The present study analyzed coherence functions in these highly affected frontal and parietal areas. Visual sensory and event related coherences of patients with Alzheimer type dementia (AD) were analyzed comparatively. A total of 38 mild, probable AD subjects (19 untreated, 19 treated with cholinesterase inhibitors) were compared with a group of 19 healthy controls. The sensory evoked coherence and event related target coherences were analyzed for delta (1-3.5 Hz), theta (4-7 Hz), alpha (8-13 Hz), beta (15-30 Hz) and gamma (28-48 Hz) frequency ranges for long-range 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) electrode pairs. The healthy control group showed significantly higher values of event related coherence in "delta", "theta" and "alpha" bands in comparison to the de nova and medicated AD groups (p<0.01 for the delta, theta and alpha) upon application of a target stimuli. In contrast, almost no changes in event related coherences were observed in beta and gamma frequency bands. Furthermore, no differences were recorded between healthy and AD groups upon application of simple light stimuli. Besides this, coherence values upon application of target stimuli were higher than sensory evoked coherence in all groups and in all frequency bands (p<0.01). The cognitive networks of AD patients were highly impaired in comparison to networks activated by sensory stimulation, thus showing separate activation of sensory and cognitive networks. (C) 2010 Elsevier B.V. All rights reserved.
- YayınSadece MetadataThermodynamical Approach To Sympathetic Cooling Of Neutral Particles(Amer Inst Physics, Circulation & Fulfillment Div, 2 Huntington Quadrangle, Ste 1 N O 1, Melville, Ny 11747-4501 USA, 2011-01-28) Borisenok, Sergey; Rozhdestvensky, YuriWe present a "toy" classical model for sympathetic cooling of the neutral Brownian particle in the frame of robust thermodynamical approach. The cooling time is expressed with the parameters of the Brownian particle and the particles from the cooling reservoir. Qualitative and numerical estimations of the model confirm that the sympathetic cooling can be efficient for heavy neutral molecules and clusters. (C) 2011 American Institute of Physics.