Comparative analysis of the role of the secondary and primary somatosensory areas of the cortex in the formation of the somatic responses of the reticular formation of the medulla oblongata in the rat

: Evoked potentials and unit activity of the medullar reticular formation were investigated in unanesthetized, immobilized albino rats either under cooling or lesion of the cortical representation of one of stimulated forepaws. The local cooling (lesion) of the cortex area C2 changed the amplitude and time parameters of the reticular evoked potentials to electrically stimulated contralateral forepaw whose representation was affected. As compared with the effect of C1 inhibition, changes in the amplitude and time parameters were insignificant and were not more then 30% and 10 ms, respectively. There were more corticofugal influences from C1 than from C2, both in experiments with evoked potentials and in analysis of somatic responses of reticular neurons. Thus corticofugal control of the medullar reticular formation in albino rats implemented by neuronic mechanisms of somatosensory areas C2 and C1 is qualitatively and quantitatively different.