The dominant motivation in the mechanisms of the conditioned reflex

It is substantiated that the mechanisms of dominant motivations play an essential role in conditioning. It is shown that motivations change convergent and chemical characteristics of single neurons of different brain structures and, especially, their sensitivity to corresponding reinforcing stimuli. As a result, motivation plays a role of an initial "canvas", against the background of which molecular "engrams of reinforcement" are built. The processes of interaction between the dominant motivation and reinforcement are mainly addressed to the apparatus of the action result acceptor. It is shown that dominant motivations participate not only in construction of molecular reinforcement engrams but also in their forestalling retrieval.     

Integration of conditioned reflex systems in intact and callosotomized dogs

Characteristics of integrative activity were studied by Kupalov's method of situational conditioned reflexes in 2 groups of dogs with complete section of the callosal body and in group of intact animals. The dogs of the first group were callosotomized before the formation of the conditioned reflex systems, the dogs of the second group--after their stabilization. The level of the reflex systems integration in the first group was considerably lower than in the second one. This testifies to a special role of the callosal body in the initial period of formation of complex conditioned systems. The callosotomized dogs developed inertia of nervous processes which was manifested in slowing down of formation and of adaptive realization of reactions during integration of various reflex systems. It was shown that the integrative activity is provided for by the interaction of cerebral hemispheres at different structural levels.     

Effect of mexidol on status of conditioned reflex activity after traumatic brain damage

Even partial hippocampal lesions in rats resulted in a disturbance of time interval determination over the course of several months (1200-1500 presentations) other complex conditioned reactions being preserved. As distinct from the control animals, the long period of failure of time interval counting was absent in rats receiving Mexidol. Continuous time conditioning took place in these animals. Due to substantial improvement of autonomic processes and emotional reactions, it was possible to present a higher number of conditioned stimuli in experiments. Mexidol seems to improve the compensatory and recovery processes after brain injuries: the impaired functions recover faster, the rate of the retrograde degeneration in the lesioned brain structures decreases, phenomena like Monakov's diaschis are not observed etc.     

A note on the equations of conditioned reflex

An alternative method is suggested for integrating a certain differential equation associated with a conditioning process, where the stimulus is presented in the form of a “square wave,” i.e., is of constant intensity during an interval of time followed by no stimulus during the next interval, etc. A solution is also given where the stimulus is a rectified sine wave.     

Functional organization of limbic brain structures during conditioned reflex activity in the dog

In experiments on 3 dogs it was shown that instrumental defensive conditioned reflex (CR) to electrical stimulation of the hippocampus is generalized within the limbic system (LS). The rate of generalization depended on the place of testing stimuli in LS. Stimulation of the medial parts of LS at the stage of stabilized initial reflex did not produce the generalized CRs, while they appeared distinctly in response to stimulation of the lateral parts of LS. In the process of elaboration of heterogeneous CRs (defensive and alimentary) to electrical stimulation of the hippocampus, generalized conditioned reactions from some brain structures appeared in both situations to the same degree while from other structures--with considerable differences. These data point to a possible participation in the genesis of the generalized CRs both of signal and reinforcing brain mechanisms.     

Functional transswitching of dominant motivation in the systems organization of behavioral acts

In experiments on rabbits, instrumental and complex conditioned alimentary behaviour was studied at various ways of raising alimentary motivation to extreme levels. Animals behaviour in these conditions could acquire an outwardly non-motivated (in relation to alimentary need) character. It is suggested that these phenomena are based on the transformation of the dominant motivation and not on the mechanism of "shifted" activity. In experiments on rats, a long "pseudoreinforcement" of extremely enhanced motivation of thirst by ethanol led to profound changes of physiological and neurochemical properties of the primary drinking motivation centres of the hypothalamus. It is suggested that such changes underlie the realization of plasticity properties of the dominant motivation.