Search PubMed⌕ Search

Biomedical subjects

W Wyrwicka

Publications and source records attributed to W Wyrwicka.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

The problem of switching in conditional behavior.

This article reviews studies of various authors on the phenomenon of "switching," which is observed in both classical and instrumental conditioning and consists in elicitation of different responses to the same conditional stimulus (CS) when it is applied in an environment different than the original one. The different responses include a decrease or an absence of the previously trained conditional response (CR), elicitation of an appetitive response instead a defensive one, or vice versa, as well as elicitation of two different instrumental CRs in the same trial. The studies suggest that, due to the repeated occurrence of CS in the same environment (E), also called "situation" or "context," associations are formed between CS and E. Consequently, the CR is elicited to a compound CS+E rather than to CS alone. When the CS is applied alone in a different E than the original one, the previously formed associations are inactive and the CR cannot be elicited; this leads to switching. Studies also suggest that E plays a dominant role in conditioning compared with that of CS alone, which often appears to be only a trigger for eliciting the response. However, CS tested in a different E may still produce some components of the previously acquired CR, such as a general fear behavior to an originally defensive CS or an approach behavior to an originally alimentary CS. The environmental stimuli can be considered the "determining" stimuli that determine the kind of reaction to be elicited, or "tonic" stimuli that increase the tonus in the brain but do not elicit the CR. The "determining" or "tonic" stimuli do not seem to be a special class of stimuli. Instead, they are stimuli that initially can produce the CR (e.g., intertrial CRs), but by being not reinforced they become partly inhibited; nevertheless, due to associations with the reinforcement, they still can produce some excitement related to it, thus facilitating the CR.

Animals↗
PubMedDate not supplied

Pavlov's position toward Konorski and Miller's distinction between Pavlovian and motor conditioning paradigms.

Two Warsaw medical students, Jerzy Konorski and Stefan Miller, having read I.P. Pavlov's works on conditional reflexes, informed him in a 1928 letter that they had discovered a new type of conditioning. A previously neutral stimulus preceded the passive lifting of a dog's paw which then was followed by feeding; this stimulus then evoked the spontaneous raising of that paw. Pavlov responded informing them that their conditioning of motor responses expanded his theory of higher nervous activity, but that their conditioning paradigm-that they named CRII-did not differ fundamentally from the Pavlovian conditioning paradigm. The replication of the Warsaw experiment in Pavlov's laboratory failed to provide unequivocal results. From 1931 to 1933, Konorski, working in Pavlov's Leningrad laboratory, further explored the parameters of CRII. Pavlov insisted that the conditioning of motor movements differs from the conditioning of other sensory analyzers only in that, on the neural level, the motor analyzer is both afferent, that is, perceptive, and efferent, that is, responsive. Konorski was not convinced, and he subsequently maintained that the two conditioning paradigms were fundamentally different.

Animals↗
PubMedDate not supplied

The sensory nature of reward in instrumental behavior.

Improvement in the sensory state, or "better-being," achieved either through obtaining desirable sensations or through escaping undesirable sensations, is considered the essential value which maintains the instrumental behavior. This value may vary depending on such factors as the intensity of the stimulus producing sensations, the effects of its previous occurrence, and the changes in the internal and external environment. Methods of evaluation of sensory "better-being" by means of measuring instrumental, autonomic and EEG responses are discussed.

Animals↗
PubMedDate not supplied

Effect of restraint on gastric acid secretion in cats.

Experiments were carried out on cats fitted with a gastric fistula. In one group of 6 cats basal gastric secretion, and in another group of 7 cats pentagastrin induced gastric secretion was collected two or three times a week during a 2 hr session. The sessions were conducted either in a "harness" situation where the cat's movements were restricted, or in a "cage" situation where the cat was unrestricted and could move freely. It was found that in four of 6 cats in the basal secretion group and in five of 7 cats in the pentagastrin induced secretion group, gastric acid output was significantly higher in sessions in harness than in sessions in cage. These differences in acid output were due to acidity rather than volume of secretion. It was hypothesized that restriction of the animal's movements in the harness could evoke a "reflex of freedom" which, however, could not be accomplished because of the confinement. This could evoke a neural conflict eventually leading to functional disturbances in the autonomic system. This, in turn, resulted in changes in gastric acid secretion.

Animals↗