Biomedical subjects

Bahar Güntekin

Publications and source records attributed to Bahar Güntekin.

3 recordsLinked to original sources

PubMed2006

Emotional face expressions are differentiated with brain oscillations.

The 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 F(3), C(z) and C(3), 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.

Adult↗

PubMed2006

A breakthrough in neuroscience needs a "Nebulous Cartesian System" Oscillations, quantum dynamics and chaos in the brain and vegetative system.

The 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 modern 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 modern 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.

Brain↗

PubMed2006

Principles of oscillatory brain dynamics and a treatise of recognition of faces and facial expressions.

The 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 ms, 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.

Animals↗