The cerebral control of the somatosensory and auditory afferent projections to the cerebral cortex in man and animals

The main purpose of the present paper was consisted in studying of topology (spreading) of the somatosensory and auditory projections in cortex of both brain hemispheres in humans under different functional states conditions: during quiet walking state and during realization of the meditative programme. At the same time for the purpose of verification these steering mechanisms a number of experiments were realized in animals with neurosurgical cutting of brainstem ascending projections, which control the transfer of somatosensory and auditory sensibility. Experimental study was realized with two groups of subjects--8 subjects (age from 25 to 35 years old) and 25 (age from 25 to 40 years old) subjects practicing technique of Transcendental Meditation (TM). In addition to the mentioned above group some groups of animals were used in the experiments. Among them there were used the groups of monkeys (8 macaque rhesus and macaque nemestrina) and cats (10 animals) in conditions of acute experiment, under tiopenthal anesthesia. Two experimental methods were used in the study: electrophysiological for subjects and neurosurgical, additionally for animals. For evaluation of the brain reactivity in subjects registration of the somatosensory, to median nerve stimulation, and auditory, to bilateral application of auditory clicks, evoked potentials (EPs) in the symmetrical cortical structures of the brain was used. Registration of the somatosensory and auditory evoked potentials in animals was realized not only from the cortex, but from the brainstem somatosensory and auditory structures. SSEP in subjects-meditators were registered before and during meditation programme. In animals SSEP and AEP registration on the corresponding stimuli realized before and after neurosurgical operation--section of the midbrain tegmentum. Specific alterations of the early (up to 80 ms) and late components SSEP and AEP complexes in forms of topology spreading and diminution of registration areas of these components were obtained during the meditation. Origins of these functional reorganization are discussed from the positions of internal 'feed-back' inhibition.