Determinant structures as functional formations: The determinant principle
The determinant phenomenon was first discovered when the functional asymmetry in the activity of the spinal cord was studied as the lumbosacral segments were locally poisoned by TT (Kryzhanovsky, 1957–1968). Clinically, this phenomenon is expressed as follows: a general seizure occurs in animals when the hind leg on the side of the poisoning is stimulated. This reaction is followed by a powerful burst of electric activity (EA) in all the muscles of the back, the tail, legs, the neck, the face, and the head (Figure 1 A). The respiratory muscles are drawn into the reaction at the late stages of the process (Figure 2). A seizure does not occur when similar stimuli are applied to the opposite leg or any other site of the body, and when distant stimuli (light, sound) are used (Figure 1 B). At the late stages, when the process is generalized, sufficiently strong nociceptive stimuli applied to the opposite leg and some other sites of the body also cause a seizure. However, the stimuli applied to a leg on the side of TT administration are the most effective ones. The animal is weakened at the last stage of a disease, when spontaneous convulsions disappear. At this stage, the animal lies prostrate, its temperature is low, and its reflexes are suppressed. Then, only the stimulation of the leg on the side of TT administration can produce a general motor reaction. Stimuli applied to the given leg can produce a reaction even during agony, when the corneal reflex is absent. This phenomenon was reproduced in animals of different species, ranging from the frog to the monkey (Kryzhanovsky et al., 1961; Kryzhanovsky, 1966a, 1966b). Hence, it is not conditioned by the species specificity of the structural and functional organization of the central nervous system of animals or the species dependence of the reaction to TT, but reflects the general regularity of the nervous system’s activity under the given conditions.
KeywordsCerebral Cortex Ventral Horn Determinant Structure Epileptic Activity Orbital Cortex
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