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In experiments with rats was studied the role of visual stimuli in conditioning of place preference in a T-shaped chamber, certain stimuli being combined with morphine injection (5 mg/kg). Intensity of illumination of the chamber sections, colour of walls, and the orientation of dark stripes on the walls were varied. Testing the animals' behaviour began with determining the reward properties of certain visual stimuli on the basis of the total time of the animals' stay in a chamber. Procedure of combining the visual stimuli with morphine was repeated four times. Associative properties of the stimuli were revealed by comparing the learning efficiency in different experimental groups. Learning within the framework of the place preference model was concluded to depend upon the reward properties of the visual stimuli, whereas the behaviour itself to be based on the mechanism of the instrumental but not the classical conditioned response.

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At the beginning the term "tolerance" determinations, given in different source of literature, have been considered. Further, the history of conditioned of tolerance and abuse creation from psycho-active drugs have been discussed. The hart of the article contains the critical points of the current representation of neurophysiological theory in the field of behavior, interaction mechanisms between live systems and drugs. The point of view, dominating in pharmacology science that tolerance is the direct result of drug substances intervention into the organism, has been opposed. Separation of primary and secondary physiological effects of drugs, allowed to the authors to conclude that the dominant role belongs to the state living system and to the presence of necessities during the motivation creations for the second drug use and to the tolerance changing.

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It has been found that bremazocine predominantly enhances the flexor reflex of the right hind limb, without affecting the left limb. The similarity of the visual data measuring the asymmetry of the pose and the asymmetry of EMG responses to painful stimulation has a high probability. No correlation between the asymmetry of the pose and EMG extensor activity has been found.

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88 adult male rats were divided into 9 groups. Group I and II served as controls. The rats of group III were repeatedly aroused during 4 days at the very onset of each paradoxical sleep period by direct MRF stimulation. This deprivation reduced the daily amount of paradoxical sleep by 70%, while the slow wave sleep was reduced by 10% only. In group IV, the animals were given food and water for one hour a day only. Groups V and VI were subjected to immobilization and cold stress, respectively. Groups VII, VIII and IX were deprived of paradoxical sleep on platforms of 15, 11 and 6.5 cm in diameter, respectively. Stress was estimated by the classical Selye's triad: weight of adrenals and thymus and gastric ulceration. Emotionality was measured in the open field and also by self-stimulation of the lateral hypothalamus. Neither emotional behaviour disturbances nor stress features were found after paradoxical sleep deprivation in the group III. Moreover, this deprivation induced a slight, though significant, reduction in adrenals weight. Also, no changes in emotional behaviour were noted in the stress-exposed group V and VI. Only the interplay between REM-sleep deprivation and stress on the platforms in groups VII, VIII and especially IX led to a considerable shift in emotionality.

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Rats were repeatedly arused from REM sleep by the stimulation via implanted midbrain reticular electrodes. The 4-day seprivation reduced REM sleep by 50% whereas the slow-wave sleep was only reduced by 10%. There was no evidence of a disruption in the animal behaviour during the deprivation and no changes of emotional responsiveness in the "open-field" at the end of the deprivation. REM deprivation produced a slight but statistically significant (P = 0.025) adrenal weightlos. Thymus weight was unchanged and no stomach ulcers developed. Therefore the REM deprivation as such did not appear to produce stress in rats.

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26 rats with bipolar electrodes in lateral hypothalamic and septal areas were learned to press the bar for electrical stimulation of the brain (monopolar square pulses, 0.1 msec, 100 cps, train length 250 msec). After stabilization of self-stimulation (SS) responses, the animals were deprived of rapid eye movement sleep (REM) for up to 4 days by confinement to a small platform surrounded by water. The rats were allowed to SS for 40 min per day during and after REM deprivation up to 1 month. It was found that REM deprivation strongly increased hypothalamic SS rates but failed to change SS thresholds. As to the septal SS, its rate either increased, with threshold unchanged or lowered (1st type), or remained steady (2nd type), or decreased, with threshold unchanged or risen. In most cases the deprivation led to alteration in the shape of SS rate/intensity curve, which remained during the whole experimental period (1 month).

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