EEG and radiothermomapping in healthy persons and Chernobyl patients during mental activity

G.D. Kuznetsova, L.A. Zhavoronkova, A.V. Gabova, V.I. Passechnik and A.B. Janovich

Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia

The present study was performed in 20 healthy persons and 36 patients, who took part in cleaning up of the Chernobyl accident's consequence, in 14 years after irradiation by low doses. EEGs and radiothermomappings were performed in awake patients during mental arithmetic and after it. EEGs were recorded from 16 electrodes and coherence coefficients were computed for 6 spectral bands for 26 intrahemispheric and 8 interhemispheric pairs. The new noninvasive method of radiothermomapping was used. 12 antennas (scheme 10?20 for EEG investigation) were placed over the head of investigated person.

In healthy persons the maximal increase of EEG coherence during calculation was observed in the frontal-temporal areas of the left hemisphere, and in the parietal areas of the right hemisphere. After mental activity coherence values had tendency to basement levels. In Chernobyl patients EEG coherence changes during mental activity were more expressed, in comparison to healthy persons, and had different dynamics. General increase of EEG coherence was observed in all brain areas in 50% of patients. An increase of EEG coherence in one hemisphere, accompanied by some diminish of EEG coherence in the other hemisphere, was obtained in 40% of patients. In 10% of persons the global lowering of EEG coherence was noticed. After mental activity, as a rule, the inversion of EEG coherence dynamics was observed: the global increase was changed by the global decrease and vice versa.

Temperature dynamics was recorded during the mental arithmetic performing (10-15 min) and after it (5 min). In healthy persons during calculation, the temperature increase was obtained in the right fronto-temporal and parietal, and left frontal and fronto-temporal cortical fields (for 30%-40% of measurements, in other cases the temperature did not change). In other brain fields, positive as well as negative temperature changes could be noticed. Temperature changes in Chernobyl patients, during and after calculation, were reliably more significant than in healthy volunteers. After calculation, healthy persons had the tendency to increase the average temperature of the brain surface, and localization of fields with increased and decreased temperature was individual. The Chernobyl patients had the tendency of the mean brain surface temperature lowering.

The investigation showed the similarity of dynamics and localization for EEG and radiothermomapping characteristics, which reflects a possible correlation between electrogenesis and local circulation of (metabolic) human brain processes. Such an approach displayed marked breach EEG and thermodynamics cognitive activity in Chernobyl patients, which could witness some remote pathological process in brain.

This work was supported by the Russian Foundation of Basic Research, grant N 00-04-48866a.


Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands

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