Springer Online Journal Archives 1860-2000
Conclusion 1. Anodal polarization of the parastriate region of the right hemisphere causes dynamic changes in EP, FIA, and interhemispheric interrelations, depending on the strength of photic stimulation, in symmetrical regions of the visual cortex. 2. During polarization the following changes arise in area 18: synergic depression of EP and left-hemispheric dominance during weak stimulation; facilitation of EP in the right hemisphere and its inhibition in the left and weakening of left-sided FIA during stimulation of average intensity; an increase in the response on the left and left-hemispheric dominance during strong stimulation. Synergic depression of EP is observed in area 17 during stimulation of weak and average intensity, and enhancement of EP in all cases of right-hemispheric dominance. 3. During polarization and in the after-period five phases of interhemispheric callosal interrelations are found in area 18: synergic depression and facilitation, reciprocal influences, unilateral depressive and facilitatory influences; the first four phases were observed in area 17. 4. At different periods of existence of a polarization focus of excitation reciprocal interactions were found between commissural influences (a combination of depressive extracallosal and facilitatory callosal influences or of facilitatory and depressive influences respectively), and also synergic interaction between depressive extracallosal and callosal influences. 5. Interhemispheric (callosal and extracallosal) influences, depending on the conditions of photic stimulation and the stage of formation of the polarization focus, either maintain initial levels of EP and FIA or bring about changes in them.
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