[Effect of geomagnetic activity on inter-hemisphere functional asymmetry of the brain].
Investigated was an impact of geomagnetic activity on incidence of "independent" early (up to 100 ms) evoked potentials (EP only in one of the hemispheres) in the head of tailed nucleus (TNH) and temporal cortex (TC) in 17 cats in the course of elaboration of food-rewarded instrumental reflex to an acoustic stimulus (click, 85 dB). Intensity of the geomagnetic activity was determined by values of the D-, H-, and Z-indices. The following 3 groups of animals were identified by the limbs dominating in implementation of the conditioned reflex: I--dextral (n = 11), II--sinistral (n = 3) and III--ambidextral (n = 3). The majority of animals in groups I and II displayed significantly higher values of "independent" EP in the left and right hemisphere, respectively, on magnetically quiescent days. On magnetically disturbed days the dextral animals would significantly increase this parameter both in TNH and TC of the right hemisphere, whereas the sinistral animals maintained the parameter high in the right hemisphere. The data suggest stimulation by increased geomagnetic activity of the right hemisphere which is more tightly bonded with diencephalic structures. Activation of the diencephalic structures and associated right-hemisphere asymmetry resulting from the bioelectrical activity in response to the tone may be indicative of rearrangement of neurohumoral interrelations due to changed difference of the terrestrial magnetic field potential as adaptive self-regulation of the function.
Makarova
I I
II
D000161:Acoustic Stimulation; D000818:Animals; D001921:Brain / Q000502:physiology*; D002415:Cats; D005071:Evoked Potentials / Q000502:physiology*; D008280:Magnetics; D012022:Reflex, Acoustic / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology