Experimental data and mathematical simulation of a neural network were used to develop ideas concerning the origin of the rhythmicity of biopotentials and its involvement in information processing. Base¬line slow oscillations – the primate α – rhythm, µ – rhythm, the α-like rhythms of lower animals, the delta – rhythm of humans and animals, secondary components of sensory evoked potentials or responses to direct brain stimulation, and pathological epileptiform potentials – develops as a result of interactions between excitatory and inhibitory postsynaptic potentials. The main inhibitory transmitter in the brain cortex is y-aminobutyric acid (GABA). EEG activation in the form of a decrease in the amplitude of baseline oscillations and the appearance of the stress rhythm in the theta band upon exposure to new or biologically significant stimuli is associated with a relative decay of inhibitory hyperpolarization processes. The cholinergic and noradrenergic neurotransmitter systems are substantially involved in the rearrangement of the neural activity associated with EEG activation. An enhancement of high-amplitude baseline oscillations and phasic activity of neurons, i.e., alternation of activation and inhibition of firing, which reflects a relative enhancement of hyperpolarization processes, restricts excitation propagation over brain structures and impedes the fixation of new information. As a result of the decay of the inhibitory processes, EEG activation is accompanied by a higher regularity of neuronal firing and a decrease in entropy in the time distribution of firing in the form of tonic or grouped (in the stress – rhythm) discharges. The resulting ordered streams of impulses transfer information, control its propagation, and ensure fixation and reproduction.
3. THE DISINHIBITION AS THE REINFORCEMENT BASIS WHEN TRAINING IN ACTIVE BEHAVIOUR.
Experiments performed on awake, non-immobilized rabbits demonstrated that, during development of a defensive conditioned reflex unconditioned stimulus (UCS) – electrocutaneous stimulation of the leg – reinforcement of a flashes – the conditioned stimulus (CS), not only evoked increased frequency of action potentials, but also shortened inhibitory intervals and attenuated post-inhibitory rebound in response to the CS as well as in baseline activity in the neurons of the neocortex and other brain structures. This disinhibition of neuronal activity after several CS-UCS pairings simulates by the effects of the CS, which becomes a signal for the reinforcement. Results of special experiments showed that the source of this disinhibitory effect is the reticular formation of the midbrain acting in conjunction with the cholinergic neurotransmitter system. The disinhibition results in increased orderliness in the time distribution of neuronal activity in the brain as result of shortening of inhibitory intervals and weakening of post-inhibitory rebound. Long-lasting ordered flows of impulses play an essential role in the process of processing and storing information in the CNS and in execution of active behaviors. Various processes at the level of systemic organization of neurons may participate in supporting disinhibition at the level of behavior. These may include: 1) an increased prevalence of excitatory effects on neurons over inhibitory ones; 2) a process of «inhibition of inhibition», in which the activity of inhibitory interneurons is turned off as a result of inhibition by the same inhibitory cells; or 3) depolarization induced suppression of inhibition (DSI), in which special molecules form as a result of the activation of nerve cells. These molecules interact with receptors located at the presynaptic contacts of inhibitory interneurons, which interferes with the release of the inhibitory mediator. Presentation and discussion of these results, with reference to data from general neurophysiology and molecular biology, suggest that disinhibition is the third specific neural process in the CNS, in addition to the processes of excitation and inhibition
4. WHEN IN THE COURSE OF EVOLUTION OF LIVING BEINGS
THERE WAS A INHIBITION OF BEHAVIOUR AND INHIBITORY
INTERACTIONS OF NERVOUS CELLS.
5. RESULTS OF EXPERIMENTAL WORK ON STUDYING OF NEUROPHYSIOLOGICAL BASES OF INTERNAL INHIBITION.
SHULGINA G.I.
6. FUNCTIONAL VALUE OF RELATIVE INCREASE IN HYPER
POLARIZING INHIBITION BY ELABORATION OF INTERNAL INHIBITION
– RESTRICTION OF THE EXIT OF EXCITEMENT TO EFFECTORS
7. PARTICIPATION OF GABA – NEUROTRANSMITTER’S SYSTEM IN ELABORATION OF INTERNAL INHIBITION