Dynamic indicators of FMA with functional loads depend on the type of load, the specialization of the hemispheres and the initial state of the subjects.
When loads are associated with the specialized activities of one of the hemispheres, there is a change in the dynamic characteristics of interhemispheric asymmetry. Studies of local cerebral blood flow, intensity of glucose consumption by the brain and EEG reveal greater activity of the right hemisphere in solving visual-spatial problems, and the left hemisphere – in pronouncing words in the mind or in a whisper, as well as in reading. When reading, the predominance of energy exchange, according to SCP, in the left hemisphere as compared with the right one is increasing. Since in the background SCP for right-handers higher in the left hemisphere, the sign of the hemispheric difference of the SCP does not change. On the contrary, when passing the test for visual-spatial orientation, the activity of the right hemisphere is significantly increased compared with the left, as evidenced by the change in the inter-hemispheric differences of SCP. If before the load in children 6 years of age, the difference between the UPP in the temporal areas (Td-Ts) was –0.94 + 0.45 mV, then after passing to the visual-spatial orientation, it was 0.37 + 0.5 mV .
A small lateralized motor load is accompanied by the activation of energy metabolism in the hemisphere, the contralateral arm used. Thus, in right-handed people 21-43 years old, when performing a sample of quick presses with the right hand, the difference of the soft starter between the left and right central regions (Cs-Cd) increased by 1.53 + 0.5 mV.
The change in the difference between the SCP under non-lateral loads is subject to other laws, caused by the development of stress reactions. If the load is of a pronounced stressor nature, for example, in athletes during the preparatory period for competitions, the change in the sign of interhemispheric asymmetry depends on two factors – on the background level of the hemispheric difference of the SCP and on the load itself, since the shift in the hemispheric difference of the SCP is associated with a negative correlation with the background of the SCP. The correlation coefficient between the background difference of the SCP in symmetrical temporal leads and the increment of this difference under the influence of the training load was 0.82 ( p <0.0001). Previously, similar patterns were obtained on animals from which an instrumental conditional was developed. reflex to pain irritation.
The restructuring of hemispheric relations plays an important role in the processes of adaptation. In healthy right-handers, the development of stress is associated with the activation of the right hemisphere. Perhaps this is due to the closer relations of the right hemisphere with Diencephalic structures, activated by stress. The connection of the right hemisphere with immunological activity, which also changes under stress, was previously described. When adapting, associated with a sharp change in climatic and geographical conditions, an inversion of the effect of the right ear was observed, which is observed normally in right-handers during dichotomous listening – simultaneous presentation of words in the right and left ear. Preemptive activation of the right hemisphere, in terms of motor proprioceptive memory, takes place in the process of adaptation to mountain conditions.While at rest in right-handed people, the alpha rhythm of the EEG in the left hemisphere is less pronounced due to its greater activation, during the process of adaptation, the predominance of the alpha rhythm in the left hemisphere was noted. Behavioral tests confirm this observation. Under polar conditions, the proportion of left-handers and ambidexters was higher compared with the population of people living in the middle lane. When preoperative stress revealed a significant increase in the asymmetry of the late components of visual evoked potentials. Increased right-hemispheric activity has been shown with PET in people after sleep deprivation, which can also be considered as stress.Under polar conditions, the proportion of left-handers and ambidexters was higher compared with the population of people living in the middle lane. When preoperative stress revealed a significant increase in the asymmetry of the late components of visual evoked potentials. Increased right-hemispheric activity has been shown with PET in people after sleep deprivation, which can also be considered as stress.Under polar conditions, the proportion of left-handers and ambidexters was higher compared with the population of people living in the middle lane. When preoperative stress revealed a significant increase in the asymmetry of the late components of visual evoked potentials. Increased right-hemispheric activity has been shown with PET in people after sleep deprivation, which can also be considered as stress.
In the sportsmen-rowers of the Olympic team, before training, the hemispheric differences of SCP were changed compared with healthy subjects of the same age, who were not experiencing extreme loads. Athletes applying for higher sporting achievements often exercise more physical activity than the adaptive reserve, and their initial value of the inter-hemispheric difference UCP often indicates activation of the right hemisphere, unlike ordinary people of middle age, who have statistically significant dominance of the left dominant hemisphere.
In male athletes, the inter-hemispheric difference of UPP in the temporal areas (Td-Ts) was not significantly different from zero (-0.73 + 1.2 mV), and in women it tended to sign inversion (0.74 + 0.7 mV) compared with the norm. Let us consider in more detail how stable the inter-hemispheric potential difference is and why the change in sign of this difference depends. In our studies, when registering SCP with an interval of 1 hour in healthy subjects aged 20 to 60 years who were in a state of calm wakefulness, there were no statistically significant changes in the distribution of SCP, including the hemispheric difference.