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A Generalized Framework for Quantifying the Dynamics of EEG Event-Related Desynchronization  [PDF]
Steven Lemm ,Klaus-Robert Müller,Gabriel Curio
PLOS Computational Biology , 2009, DOI: 10.1371/journal.pcbi.1000453
Abstract: Brains were built by evolution to react swiftly to environmental challenges. Thus, sensory stimuli must be processed ad hoc, i.e., independent—to a large extent—from the momentary brain state incidentally prevailing during stimulus occurrence. Accordingly, computational neuroscience strives to model the robust processing of stimuli in the presence of dynamical cortical states. A pivotal feature of ongoing brain activity is the regional predominance of EEG eigenrhythms, such as the occipital alpha or the pericentral mu rhythm, both peaking spectrally at 10 Hz. Here, we establish a novel generalized concept to measure event-related desynchronization (ERD), which allows one to model neural oscillatory dynamics also in the presence of dynamical cortical states. Specifically, we demonstrate that a somatosensory stimulus causes a stereotypic sequence of first an ERD and then an ensuing amplitude overshoot (event-related synchronization), which at a dynamical cortical state becomes evident only if the natural relaxation dynamics of unperturbed EEG rhythms is utilized as reference dynamics. Moreover, this computational approach also encompasses the more general notion of a “conditional ERD,” through which candidate explanatory variables can be scrutinized with regard to their possible impact on a particular oscillatory dynamics under study. Thus, the generalized ERD represents a powerful novel analysis tool for extending our understanding of inter-trial variability of evoked responses and therefore the robust processing of environmental stimuli.
EEG Seizure duration during ECT : Effect Of Concurrent Psychotropic Drugs
Girish K,Gangadhar B N,Janakiramaiah N,Sarvanan E S M
Annals of Indian Academy of Neurology , 2003,
Abstract: This study examined the concurrent use of psychotropic drugs on seizure duration during Electroconvulsive therapy (ECT). Consecutive consenting patients prescribed bilateral ECT (n=182) by the treating psychiatrist were considered for the study. The concurrent psychotropic medication (antipsychotic, antidepressant, benzodiazepine and lithium) was recorded. Motor and EEG seizure durations were recorded at threshold ECT session. The seizure durations were compared between the co-administered drug and control groups for each of the psychotropic drug independently using students′ t-test. Concurrent antipsychotic or antidepressant drugs had no influence on seizure duration. However, the seizure duration was longer in patients on lithium (n=30) and shorter in patients on benzodiazepines (n=67). Prolonged seizures occurred more often in the former (26.6%) but less often in the later (12%). Polypharmacy in these patients precludes firm conclusions. Findings however, point to the need for discontinuing concurrent administration of lithium and benzodiazepines during ECT.
Driver’s alertness detection for based on eye blink duration via EOG & EEG
Yash S. Desai
International Journal of Advanced Computer Research , 2012,
Abstract: This paper presents an EEG-EOG based alertness detection system for vehicle drivers. As lots of algorithms based on signal processing of EEG, EOG, facial EMG & facial gesture image processing. Though these have disadvantages that complex in nature. Our algorithm is based on measure of time duration between blink movements of eye. Normal time duration between eye blink patterns is measured by several observations. Algorithm is set such that If the time duration between blink patterns is more than normal than person may napped or not in alert stage. The basic EEG-EOG acquisition system is made and time duration algorithm set through signal processing tool kit in mat lab. Time duration between blink signals crosses the sated reference time that means driver is obviously in abnormal stage maybe in napped or fatigue condition. However both dangerous for driving. We can also design simple hardware, just measuring time duration between two consecutive picks of blink signal which is as same as measure of ECG R to R interval circuit and when we find time duration just beyond reference time we have to trigger on devices that make driver alert or we can give that impulse to device such as energy pulse generator, speaker to make driver alert and that can easily prevent threats of sudden accident.
Effects of Cold Pressor Stress on the Human Startle Response  [PDF]
Christian E. Deuter, Linn K. Kuehl, Terry D. Blumenthal, André Schulz, Melly S. Oitzl, Hartmut Schachinger
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049866
Abstract: Both emotion and attention are known to influence the startle response. Stress influences emotion and attention, but the impact of stress on the human startle response remains unclear. We used an established physiological stressor, the Cold Pressor Test (CPT), to induce stress in a non-clinical human sample (24 student participants) in a within-subjects design. Autonomic (heart rate and skin conductance) and somatic (eye blink) responses to acoustic startle probes were measured during a pre-stress baseline, during a three minutes stress intervention, and during the subsequent recovery period. Startle skin conductance and heart rate responses were facilitated during stress. Compared to baseline, startle eye blink responses were not affected during the intervention but were diminished afterwards. These data describe a new and unique startle response pattern during stress: facilitation of autonomic stress responses but no such facilitation of somatic startle eye blink responses. The absence of an effect of stress on startle eye blink responsiveness may illustrate the importance of guaranteeing uninterrupted visual input during periods of stress.
Premenstrual seizure increase influence of age, duration of disease, seizure frequency, previous complaint of perimenstrual accentuation, eeg and ct scan findings
Gueirreiro, Carlos A. M.;Ramos, Marcelo C.;
Arquivos de Neuro-Psiquiatria , 1991, DOI: 10.1590/S0004-282X1991000100004
Abstract: we selected prospectively 80 mentally healthy women at menacme age, with chronic epilepsy and at least one seizure in the month preceding this study. they underwent four eegs weekly. ct scan of the skull was done in 57 patients (71.25%). seven patients were excluded because they had no seizures or menses. we registered 5630 seizures during 579 regular menstrual cycles over a 30 month period. results: - there was a higher incidence of seizures in the premenstrual period (p<0.001); - age did not influence the distribution of seizures during the menstrual cycle in the group studied; - patients with 11 or more years of disease showed more accentuation of premenstrual seizures than patients with 10 or less years of disease; - there was no relation between the patients frequency of seizures and the occurrence of premenstrual seizures; - the patients impression of the incidence of seizures not related to menstruation was not confirmed; - patients with abnormal skull ct scans had more accentuation of premenstrual seizures than patients with normal exams; - patients with abnormal eegs had more premenstrual seizures than patients with normal exams. our findings suggest that the female sexual hormones alter cerebral excitability when there is an underlying structural pathology shown by ct scan or an electrical cerebral dysfunction revealed by eeg.

Ai Zhuming,Kou Jianqiu,

生物物理学报 , 1996,
Abstract: The EEG in lead - administrated rats is measured and analyzed using the method of chaotic time series analysis in this paper. The fractal dimension of EEG is determined. From the study we get the relationship between the amount of lead administration and the fractal dimension of EEG. The result shows that lead administration can cause the evident change of fractal dimension of the EEG. The research work has provided a new convenient and sensitive examination method for early clinical diagnosis for heavy metal poisoning.
Thermal Imaging of the Periorbital Regions during the Presentation of an Auditory Startle Stimulus  [PDF]
Luke Gane, Sarah Power, Azadeh Kushki, Tom Chau
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027268
Abstract: Infrared thermal imaging of the inner canthi of the periorbital regions of the face can potentially serve as an input signal modality for an alternative access system for individuals with conditions that preclude speech or voluntary movement, such as total locked-in syndrome. However, it is unknown if the temperature of these regions is affected by the human startle response, as changes in the facial temperature of the periorbital regions manifested during the startle response could generate false positives in a thermography-based access system. This study presents an examination of the temperature characteristics of the periorbital regions of 11 able-bodied adult participants before and after a 102 dB auditory startle stimulus. The results indicate that the startle response has no substantial effect on the mean temperature of the periorbital regions. This indicates that thermography-based access solutions would be insensitive to startle reactions in their user, an important advantage over other modalities being considered in the context of access solutions for individuals with a severe motor disability.
Non-Linear EEG Measures in Meditation  [PDF]
Old?ich Vy?ata, Martin Sch?tz, Jakub Kopal, Jan Burian, Ale? Procházka, Kuchyňka Ji?í, Jakub Hort, Martin Vališ
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.79072
Abstract: In this study, the performance of Sevcik’s algorithm that calculates the fractal dimension and permutation entropy as discriminants to detect calming and insight meditation in electroencephalo-graphic (EEG) signals was assessed. The proposed methods were applied to EEG recordings from meditators practicing insight meditation and calming meditation before as well as during both types of meditation. Analysis was conducted using statistical hypothesis testing to determine the validity of the proposed meditation-identifying techniques. For both types of meditation, there was a statistically significant reduction in the permutation entropy. This result can be explained by the increased EEG synchronization, which is repeatedly observed in the course of meditation. In contrast, the fractal dimension (FD) was significantly increased during calming meditation, but during insight meditation, no statistically significant change was detected. Increased FD during meditation can be interpreted as an increase in self-similarity of EEG signals during self-organisation of hierarchical structure oscillators in the brain. Our results indicate that fractal dimension and permutation entropy could be used as parameters to detect both types of meditation. The permutation entropy is advantageous compared with the fractal dimension because it does not require a stationary signal.
Modulation of the Startle Reflex during Brief and Sustained Exposure to Emotional Pictures  [PDF]
Aimee Mavratzakis, Elaine Molloy, Peter Walla
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.44056

Previous investigations using pictures to elicit an emotional response have shown that the startle reflex habituates over time due to decreased excitation in the obligatory startle processing pathway, an effect that is independent of emotion modulation aspects of the startle response. However, in some instances, startle magnitude has been selectively potentiated during sustained exposure to passively viewed unpleasant pictures. This study assessed startle modulation during brief, alternating and sustained exposure to emotional pictures. Self-reported ratings of emotion were collected online with picture viewing to determine if any change in startle magnitude was observable in explicit emotional responses. Self-reported ratings of pleasantness and arousal were no different across the brief and sustained picture presentations. However, a significant main effect (independent from emotion category) of presentation condition was found for startle magnitudes, showing that, contrary to previous research involving passive picture viewing, mean startle magnitudes during sustained exposure were reduced relative to brief exposure. These findings are likely the result of a general habituation of the startle reflex in the obligatory pathway. The findings are also discussed in terms of the effect of the concurrent emotion rating task, which may have differently affected the cumulative effects of emotion exposure compared to passive picture viewing.

How Long is the 'Present': The EEG Study of the Characteristic of Empty Duration Cognition Segmentation

YU Xiaolin
,HUANG Xiting,CHEN Youguo,QIU Junjie

- , 2018, DOI: 10.13718/j.cnki.xdsk.2018.03.015
Abstract: 人们体验到的“现在”的限度并非一成不变,与时间知觉具有相同的内涵。为探讨人们对空时距形式呈现的“现在”的限度,本研究采用脑电图(EEG)技术,以theta(4-8 Hz)和alpha波(8-12 Hz)功率为指标,考察在工作记忆的保持阶段,1~4 s空时距知觉的分段性,结果发现:不同时距条件在theta波波幅上无显著差异,而2s、3s和4s时距条件的alpha波波幅却显著低于1s条件,表现出分段性,且分界线为1s,说明人们对空时距形式呈现的“现在”的限度约为1s,短于实时距(2s)。本研究首次从神经表征的层面对空时距进行了探讨,并发现时距类型是影响“现在”的限度的因素之一。
The limit of 'present' has the same connotation with time perception. In this study, a matching-to-sample task was adopted to explore the characteristic of 1~4s empty duration cognition segmentation using electroencephalogram (EEG) recordings. The EEG results showed that the length of duration retained in WM was not associated with changes in theta amplitude, whereas the alpha amplitude especially in the posterior during 2s, 3s and 4s duration conditions were significant lower than that of 1s. It indicated that the neural representation of empty duration is segmented, with a critical threshold point of approximately 1s. It is the limit of 'present' presented in form of empty duration. Our study provides electrophysiological evidence for empty duration cognition segmentation. Additionally, the limit of 'present' is affected by the type of duration after comparing with the previous finding about filled duration, but is not suitable for explanation by the length of perceived duration
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