Shugurov O. Mechanisms of formation of the evoked potentials of spinal cord in norm and pathological cases.

The object of study: Neurons and neuronal ensembles in lyumbo-sacral part of the spinal cord that carry transformation of the sensorimotor information in descending motor and ascending sensory way on the spinal level. The objective of research is to identify of laws of communication volume characteristics of the spinal cord with the mechanisms of formation of the constituent elements of evoked potentials for non-invasive diagnosis of the functional state of the brain in normal conditions or under the influence of external negative factors. Methods. The electrophysiological macro- and microelectrode technique, the polarization of the nerve or spinal cord, the averaging and triggered of electrical signals, methods of microscopy and morphometry, the mathematic analysis and simulation were used in study. Theoretical and practical results, the novelty. In studies on cats we found a new components of the evoked potential of spinal cord and evaluated their options. The neuronal structure, which generate such signals were studied. First time was conducted a comprehensive study of state of the distribution of the amplitudes of the main components of evoked potentials on the perimeter and the length of the spinal cord in lumbar-sacral region of spinal cord in normal and injury of dorsal roots. We have shown that a decrease of the amplitudes of all components from the point of their maximum in the cranial direction is a less steep than in the sacral. It is shown that transection of the dorsal roots of the lumbosacral thickening is lead to the formation of local maxima and minima in these distributions. New mathematical criteria to describe the transition of spinal neural systems from a passive to an active state and an objective assessment of the integrity of the monosynaptic systems "fiber-to-neuron" have been proposed. We also determined the optimums frequency activation of neuronal groups that generate the components of the evoked potential and showed the importance of changing the level of modulation of the activity in the processing of information in the spinal afferents inputs. For the first time revealed that the spinal cord potentials are able to change in case of normal aging. Also shown that such factors as the mechanical concussion of brain, spinal anesthesia, microwave fields and X-rays - all they cause the specific changes of the parameters of the components of evoked potentials. These changes are significantly depend on the location of neural systems with respect to a particular point of influence of this factor. Conclusions about the usefulness of evoked potentials in the electrophysiological non-invasive diagnosis of the state of the brain were made. Scope of the work. The data obtained can be recommended in practical physiology and medicine for non-invasive assessment of the functional state of the central nervous system and spinal cord, particularly in health in analysis of the actions of external influences on the brain. The results can be used in the preparation of specialists in the field of general biology, medicine, physiology, neurosurgery, biocybernetics, control systems, neuro- and biocomputer technology.