RESEARCH PAPER
Spectral analysis of EEG signals among people with different levels of personal anxiety
 
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Lesia Ukrainka East European National University
CORRESPONDING AUTHOR
Olena Dmytrotsa   

Lesia Ukrainka East European National University, Nikishewa 14, 43010 Lutsk, Ukraine
 
J Pre Clin Clin Res. 2018;12(1):22–25
 
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ABSTRACT
Introduction:
The study of electrical activity peculiarities in the cerebral cortex among people with different levels of anxiety and the dependence of EEG rhythms from the level of personal anxiety (PA) is relevant and needs to be studied. As a result of our research, we have found that during the baseline EEG among people with a moderate level of personal anxiety, the intensity of alpha rhythm predominates in the posterior areas of the cerebral cortex. People with a high level of PA had the highest rates of beta rhythm intensity. An inverse relationship between EEG main rhythms and the level of anxiety is noted. Thus, people, who were involved in our study, with the moderate level of PA had the following results: the steadier the PA, the less the intensity of the PA level. People with a high level of PA had positive connections between the alpha and beta rhythms and level of anxiety, as well as a higher activity in the right-hemisphere of the cortex, which indicates the contribution of this hemisphere in the high level PA in studies.

Material and methods:
The power of EEG rhythms among people (aged 18–22) with different levels of anxiety was studied. Registration of the cerebral cortex electrical activity was carried out using the «Neurocom».device. During the electroencephalogram recording, electrodes were placed on the international system 10/20. The spectral power values were analyzed in the standard physiological frequency bands: delta (1–4 Hz), theta (4–8 Hz), alpha (8–14 Hz), beta (14–35 Hz). For the spectral EEG characteristics, an absolute (ACP, μV) and relative spectral power (RSP, %) were used. The analysis of power indices was carried out in a state of rest with closed eyes (baseline),and a state of rest with open eyes during task solving as an emotional load.

Results:
We have found that during the EEG baseline people with the moderate level of PA had high indexes of alpha rhythm in the posterior areas of the cerebral cortex. Eyes’ opening caused an increase of the intensity of theta rhythm in the frontal area of the cerebral cortex. During the intellectual task conducting, we noticed that the increase of intensity of beta rhythm in the frontal, temporal and end-lobe parts, whereas in the central and vertex parts of the cortex the intensity of theta rhythm predominated. Among people with a high level of PA during the baseline probe, the highest rates of beta rhythm intensity in the posterior areas of the cerebral cortex were fixed. In the state of rest with open eyes, the activity of theta rhythm was revealed. The alpha rhythm had the highest rates of intensity in the posterior area of the right hemisphere. During the intellectual task, the intensity of beta rhythm predominated. In the frontal and central parts of the cortex, the intensity of theta rhythm predominated.

Conclusions:
During the baseline probe among people with a moderate level of PA, the intensity of alpha rhythm in the posterior areas of the cerebral cortex predominated, among people with a high level of PA – beta rhythm. eyes open caused an increase in the intensity of theta rhythm in the frontal area of the cerebral cortex of people with a moderate level of PA, and alpha rhythm in the posterior area of the right hemisphere. During the intellectual task conducted among people with a moderate level of PA, we noticed an increase in beta rhythm intensity in the frontal, temporal and end-lobe parts, but in the central and vertex parts of the cortex the intensity of theta rhythm predominated. While in another group of people who were involved in study, the intensity of beta rhythm predominated; in the frontal and central parts – theta rhythm. With a moderate level of PA, there were significant negative links between the level of anxiety and intensity of alpha, beta, theta rhythms. With a high level of PA, positive links between the intensity of alpha and beta rhythms and the level of anxiety were noticed; the intensity of EEG rhythms in this group of examined people was correlated with the right parts of the brain, which indicates to a big contribution of this part in the high level of PA among the examined people.

 
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