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This is a pilot study describing event-related oscillations in patients with Alzheimer-type dementia (AD). Theta responses of 22 mild probable AD subjects according to NINCDS-ADRDA criteria (11 non-treated, 11 treated by cholinesterase inhibitors), and 20 healthy elderly controls were analyzed by using the conventional visual oddball paradigm. We aimed to compare theta responses of the three groups in a range between 4-7 Hz at the frontal electrodes. At F-3 location, theta responses of healthy subjects were phase locked to stimulation and theta oscillatory responses of non-treated Alzheimer patients showed weaker phase-locking, i.e. average of Z-transformed means of correlation coefficients between single trials was closer to zero. In treated AD patients, phase-locking following target stimulation was two times higher in comparison to the responses of non-treated patients. The results indicate that the phase-locking of theta oscillations at F-3 in the treated patients is as strong as the control subjects. The F-4 theta responses were not statistically significant between the groups. Our findings imply that the theta responses at F3 location are highly unstable in comparison to F4 in non-treated mild AD patients and cholinergic agents may modulate event-related theta oscillatory activities in the frontal regions. (c) 2006 Elsevier B.V. All rights reserved.

The surface flux transport (SFT) model of solar magnetic fields involves empirically well-constrained velocity and magnetic fields. The basic evolution of the Sun's large-scale surface magnetic field is well described by this model. The azimuthally averaged evolution of the SFT model can be compared to the surface evolution of the flux transport dynamo (FTD), and the evolution of the SFT model can be used to constrain several near-surface properties of the FTD model. We compared the results of the FTD model with different upper boundary conditions and diffusivity profiles against the results of the SFT model. Among the ingredients of the FTD model, downward pumping of magnetic flux, related to a positive diffusivity gradient, has a significant effect in slowing down the diffusive radial transport of magnetic flux through the solar surface. Provided the pumping was strong enough to give rise to a downflow of a magnetic Reynolds number of 5 in the near-surface boundary layer, the FTD using a vertical boundary condition matches the SFT model based on the average velocities above the boundary layer. The FTD model with a potential field were unable to match the SFT results., Accepted for A&A

Background: Visual delta event-related (ERO) and evoked oscillations (EO) of Alzheimer patients (AD) are different than healthy. In the present study, the analysis is extented to include auditory ERO and EO in AD. The rationale is to reveal whether the auditory ERO delta responses are also reduced, and whether this is a general phenomenon in Alzheimer patients upon applying stimuli with cognitive load. Methods.: Thirty-four mild AD subjects 117 de-novo and 17 medicated (cholinergic)l and seventeen healthy controls were included. Auditory oddball paradigm and sensory auditory stimuli were applied to the subjects. Oscillatory responses were analyzed by measuring maximum amplitudes in delta frequency range (0.5-3.5 Hz). Results: Auditory delta ERO (0.5-3.5 Hz) responses of healthy controls were higher than either de-novo AD or medicated AD group, without a difference between two AD subgroups. Furthermore, the auditory EO after presentation of tone bursts yielded no group difference. Conclusion: Our findings imply that delta ERO is highly unstable in AD patients in comparison to age-matched healthy controls only during the cognitive paradigm. Our results favor the hypothesis that neural delta networks are activated during cognitive tasks and that the reduced delta response is a general phenomenon in AD, due to cognitive impairment.

In 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

Already in 1940s several neurophysiologic, biochemical and physical discoveries took place and the conjecture was open for the initiation of the "Quantum Brain Concept". The present essay explains the ensemble of discoveries that could lead to the quantum brain concept and tries to find out the reason, why this concept was delayed during many decades.

Diagnosis and treatment of Alzheimer's disease (AD) depend on clinical evaluation and there is a strong need for an objective tool as a biomarker. Our group has investigated brain oscillatory responses in a small group of AD subjects. We found that the de novo (untreated) AD group differs from both the cholinergically-treated AD group and aged-matched healthy controls in theta and delta responses over left frontal-central areas after cognitive stimulation. On the contrary, the difference observed in AD groups upon a sensory visual stimulation includes response increase over primary or secondary visual sensorial areas compared to controls. These findings imply at least two different neural networks, depending on type of stimulation (i.e. cognitive or sensory). The default mode defined as activity in resting state in AD seems to be affected electrophysiologically. Coherences are also very valuable in observing the group differences, especially when a cognitive stimulus is applied. In healthy controls, higher coherence values are elicited after a cognitive stimulus than after a sensory task. Our findings support the notion of disconnectivity of cortico-cortical connections in AD. The differences in comparison of oscillatory responses upon sensory and cognitive stimulations and their role as a biomarker in AD await further investigation in series with a greater number of subjects.

This report describes the importance of oscillations in brain function and introduces metaphors to quantum dynamics. In order to analyze scattering processes at the level of elementary particles Werner Heisenberg proposed the use of the so-called S-Matrix to understand nuclear interactions by studying ingoing at outgoing particles. Later, Richard Feynman developed useful schemes in order to visualize processes of elementary particle interactions. In the present report a metaphor to Feynman Diagrams is developed in order to model the “Ongoing Brain Activity and Event Related Oscillations”. The response susceptibility of the brain shows a probabilistic causality similar to uncertain processes in elementary particle physics. A new grammar called Brain Feynman Diagrams is proposed in order to show brain oscillatory responses as a more visible construct in comparison to conventional compound brain potentials.

Charles Darwins's evolution theory was surveyed and analyzed by Henri Bergson in his book "Evolution Creatrice" (1907). Bergson described the importance of "intuition" and "cognitive processes" during evolution. The present essay describes the importance of entropy changes during evolution of species and development of cognition and intuition. The importance of Bergson's philosophy in modern sciences is globally explained.

Background and purpose: Alzheimer type of dementia (AD) is the most common neuropsychiatric morbidity in elderly individuals. Event-related oscillations (ERO) provide an useful tool for detecting subtle abnormalities of cognitive processes with high temporal resolution. Methods: In the present report, event-related oscillations of patients with AD were analyzed by using a visual oddball paradigm. A total of 22 mild probable AD subjects according to NINCDS-ADRDA criteria and 20 age-, gender-, and education-matched healthy control subjects were compared. AD group consisted from 11 untreated patients and 11 patients treated with cholinesterase inhibitor. Oscillatory responses were recorded from 13 scalp electrodes. Results: Significant differences in delta frequency range were seen between the groups by using repeated measures of ANOVA analysis [F(9.120) = 2.228; P = 0.022]. Post-hoc analyses using Wilcoxon test showed that at mid- and left central regions, (Cz, C3) peak amplitudes of delta responses of healthy subjects were significantly higher than either group. Also cholinesterase inhibitors did not have effect on delta oscillatory responses. Conclusions: Our findings imply that the delta oscillatory responses at central locations are highly instable in mild probable AD patients regardless of treatment when compared to the healthy aged controls. This study supports the importance of oscillatory event-related potentials for investigating AD brain dynamics.

TEZ5886 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2006. Kaynakça (s.130-135) var. xix, 147 s. : res. ; 29 cm. The shear flow of a fully turbulent boundary layer along a perforated plate, which is bounded by a closed cavity on its backside, can give rise to highly coherent, self-sustained oscillations. These oscillations are characterized in terms of unsteady pressure fluctuations and quantitative images of the instantaneous and averaged flow structure using a technique of high-image-density particle image velocimetry (PIV). Kapalı bir kavite üzerine yerleştirilmiş gözenekli bir levha boyunca oluşmuş tam türbülanslı sınır tabaka içerisinde kendili inden sürekli salınımlar oluşur. Bu çalışmada parçacık görüntülemeli (PIV) hız ölçme metodu kullanılarak anlık ve ortalama hız değerleri, girdap çizgileri, Reynolds gerilmeleri ve levha boyunca belli bir zaman aralığında ölçülen basınç değerleri ile bu salınımlar ifade edilmiştir. Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi Tarafından Desteklenmiştir. Proje No