Early consequences of lithium-pilocarpine convulsive status epilepticus (SE) were studied six days after this status had been induced in rat pups at the age of either 12 or 25 days. Studies of spontaneous EEG activity demonstrated the presence of epileptic phenomena (isolated spikes) in both hippocampus and cortex (cortical spikes were more expressed in the older group). There were no marked behavioral correlates of spikes and transition into the ictal phase was exceptional. The motor performance on a rotorod and a horizontal bar was the same in experimental and control rats of both ages. Behavior in the open field was changed in a reverse manner in the two age groups: the locomotor activity of rats with induced seizures at the age of 12 days was significantly lower than that of their control siblings, whereas animals undergoing status at the age of 25 days were hyperactive. In addition, they also exhibited increased exploratory activity (rearing) and their habituation to the open field was deranged. Nissl-stained brain sections demonstrated extensive brain damage in the older group in contrast to the negative findings in younger animals. EEG, behavioral and morphological changes induced by status epilepticus in developing rats persisted for 6 days after the status. They markedly differed according to the age of animals., L. Suchomelová, H. Kubová, R. Haugvicová, R. Druga, P. Mareš., and Obsahuje bibliografii
The operator is required to be constantly vigilant and even more attentive when operating the device. The paper introduces a cooperation of a car simulator realized in the virtual reality (VR) environments and measurements of "human driver behavior" focused mainly on the aspects of HMI and drivers' attention decrease. In the first part a conception and a development of our VR car simulation devices are described. During the development of the car simulators many problems need to be solved. One of these problems is represented by a simplification and a partial automation of a scenery creation. The first part is dedicated to the algorithms used in our tools, which help to automate the creation of virtual scenes. The next part analyses, in greater detail, the tools themselves and the rest of this section deals with demonstration of the scenes, which were modeled using these tools. For simpler and faster generation of virtual sceneries it is suitable to store the models within a hierarchical database 3D object. Our database includes model objects from which it subsequently forms surroundings for the road virtual scenes. In the article is described how to specify the 3D model properties - their fundamental characteristic and consequent differentiation into specific categories. Sound perception cues are one of the most important ones besides the visual cues in the car simulation. The audio section of this article deals with simulating a sound of a car engine as a most significant audio stimulant for the driver. It shows the basics of the cross fading system which renders the car audio from multiple looped samples. The first part contains an analysis of car engine sound, the second part describes how to synthesize it on the computer. Validation measurements and consequent results are shown at the end of this section. The final paragraphs show examples of experiments developed for measurements of the driver's fatigue and other aspects of the driver's behavior.
Human society needs still more intensive exploitation of all kinds of
transportation facilities. This need has already lasted for several decades and will be much more imperative in future. Mobility is one of the basic requirements for survival, besides the energy and food resources, health care and security. The requirements on transportation systems concern not only the quantitative and qualitative aspects of transportation activities, but still more also the aspects of their reliability and safety. This concerns not only the transported subjects or goods but also the environment.
The losses caused by failures of transportation activities reach even now a very high level and if not limited by systematic research and preventive activity, they will reach quite a tremendous level soon.
However, practically all the conternporary transportation vehicles, trains, ships and planes and also all the transportation systems need, for their proper operation, the interaction with human beings, which drive them, controls them or uses them and maintains them.
In spite of the fact that significant progress was made in recent years as concerns the transportation systems automation, the fully automatic transportation systam in use is still foreseen in the considerably far future.
Analyzing the reliability and safety of transportation, one finds that the activity of a human being is the weakest point. The technical reliability of almost all transportation tools has improved quite a lot in the past years; however, the human subject interacting with them has not changed too much, as for his/her reliability and safety of the respective necessary interaction.
Therefore there is a vital necessity to improve it and the possibilities how to implement it will stay more and more in the focus of our interest.
In this paper an overview of the related problems is made, the challenges for further research and development in this area are discussed and the outline of a vision, with respect to human interaction reliability, of optimized transportation systems is presented.
Chaotic transitions likely emerge in a wide variety of cognitive phenomena and may be linked to specific changes during the development of mental disorders. They represent relatively short periods in the behavior of a system, which are extremely sensitive to very small changes. This increased sensitivity has been suggested to occur also during retrieval of stressful emotional experiences because of their fragmentary, temporally and spatially disorganized character. To test this hypothesis we recorded EEG during retrieval of fearful memories related to panic attack in 7 patients and retrieval of anxiety-related memories in 11 healthy controls. Nonlinear data analysis of EEG records showed a statistically significant increase in degree of chaotic dynamics after retrieval of stressful memories in majority of patients as well as in control subjects. This change correlated with subjective intensity of anxiety induced during the memory retrieval. The data suggest a role of nonlinear changes of neural dynamics in the processing of stressful
anxiety-related memories, which may play an important role in the pathophysiology of panic disorder.
Digital signal processing techniques are often used for measurement of small time shifts between EEG signals. In our work we tested properties of linear cross-correlation and phase/coherence method. The last mentioned method was used in two versions. The first version used fast Fourier transform (FFT) algorithm and the second was based on autoregressive modeling with fixed or adaptive model order. Methods were compared on several testing signals mimicking real EEG signals. The accuracy index for each method was computed. Results showed that for long signal segments all methods bring comparably good results. Accuracy of FFT phase/coherence method significantly decreased when very short segments were used and also decreased with an increasing level of the additive noise. The best results were obtained with autoregressive version of phase/coherence. This method is more reliable and may be used with high accuracy even in very short signals segments and it is also resistant to additive noise.
The paper technically describes the principles of incorporation of the biofeedback system into the system of a driving simulator. After a brief introduction of the basic features of EEG biofeedback, the most important scenarios where such simulator enhancement can be successfully used are described. The system is introduced with the use of an analysis of the major technical and construction aspects, such as the software design, hardware realization and its incorporation into the driving simulator system. Finally, the paper sketches pilot experiments which were performed using EEG biofeedback incorporated into the driving simulator.
This paper introduces the cooperation of a virtual car simulator and
EEG measurements to test a human driver’s behavior in demanding situations. After a short explanation of the main principles and tasks of EEG measurements, basic concepts of our experiments are presented. The following part is devoted to problems and solutions concerning the physical model, graphical and other aspects of our simulator. At the end of the article various measuring procedures are presented.
Two doses of alprazolam (0.1 and 0.5 mg.kg“1) were tested against a model of human absences - rhythmic EEG activity elicited by low doses of pentylenetetrazol (35 mg.kg-1) - in 10 unrestrained rats with implanted cortical electrodes. Alprazolam delayed the onset of epileptic EEG activity, decreased the number of rhythmic episodes and shortened the total duration of rhythmic activity in a dose-dependent manner. The average duration of episodes of rhythmic activity remained unchanged; other benzodiazepines studied previously were able to influence this measure.
The goal of this paper is to desigen a system for the detection and evaluation of the decrease of drivers’ attention. The paper refers to possible reasons and risks of a phenomenon called micro-sleep. It also describes the measurement methodology. The paper apprise of a new way of detection and evaluation of microsleep. The methods of fuzzy systém and knowledge systém is used. The state of the proband is assessed by classification modules F-COMS and C-COMS which were designed specifically for these systems. The paper also describes the individual frequencies of an EEG spectrum including their mutual dependencies in particular states and individual contributions in a detailed way. The conception of the proposed system for detection and evaluation of the decrease of attention ensues from the uniqueness of an individual, and the inaccuracy of measurement on humans, as well as from the universality of a systém construction, capable of detecting not only the inattention of a driver, but also his/her maximum concentration or pathological changes.