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Biomedical subjects

R F Westbrook

Publications and source records attributed to R F Westbrook.

60 records · Page 4Linked to original sources
PubMed1979

The effects of lithium upon drinking in the pigeon and rat.

Single administrations of LiCl in fluid deprived pigeons produced immediate and sustained drinking which was (a) significantly greater than in NaCl-injected birds, (b) a function of the dosage of lithium, and (c) persistent for several days following the highest dosage used. Experiment 2 employed the same procedures to examine the effects of lithium upon fluid consumption in the rat. Results indicated that single administrations of lithium had little effect on water consumption.

Animals↗
PubMed1978

Control of polydipsic drinking by a taste aversion procedure.

Rats were given daily sessions with free access to food and saccharin flavored water. After fluid consumption had stabilized food was delivered once every minute. Water was always available in the home cage. All rats showed the marked increase in fluid consumption known as schedule-induced polydipsia. The rats were then poisoned with lithium chloride after each of three sessions in an attempt to condition a taste aversion to the saccharin. On recovery from the toxicosis all rats showed first a reduction and then a recovery in saccharin intake. To establish the nature of this effect, the rats were poisoned after saccharin consumption in the home cage. Again there was a marked reduction in polydipsic drinking in the experimental chamber. These results indicate that common incentive mechanisms govern normal and polydipsic drinking and stand in contrast to published results pointing to different drive systems in the brain mediating normal and polydipsic drinking.

Animals↗
PubMed1973

Failure to obtain positive contrast when pigeons press a bar.

In Experiment 1, two groups of pigeons were exposed to multiple variable-interval 1-min variable-interval 1-min schedules of reinforcement. The required response was a key peck for one group, and a foot press of a bar for the other. When the procedure was shifted to multiple variable-interval 1-min extinction, positive contrast occurred with pigeons that key pecked, whereas negative induction occurred with those that bar pressed. Moreover, the absence of contrast could not be ascribed to the lack of inhibition, since negative generalization gradients after bar press training were U-shaped in Experiment 2. The results are discussed in terms of possible relationships between positive contrast and the phenomenon of autoshaping.

Journal Article↗
PubMed1973

Interactions in multiple schedules with different responses in each of the components.

Pigeons were exposed to multiple schedules in which a key was lit in one component and a bar was present in the other. Ten subjects were trained to peck the key and to press the bar with their feet, and four subjects were trained to peck both the bar and the key. After a period of exposure to variable-interval reinforcement in both components, subjects were exposed to extinction in one component. Only one of the 10 pigeons in the key-peck:bar-press condition showed an increase in rate in the other component, while seven of them showed a decrease. In the key-peck:bar-peck condition, three of the four subjects showed positive contrast. The data suggest that a condition for contrast to occur is that topographically similar behaviors be required in both components of the multiple schedule.

Journal Article↗
PubMed1970

The effect of a fading procedure upon the acquisition of control by an overshadowed auditory feature.

Pigeons' key-pecking responses were reinforced in the presence of a compound stimulus that consisted of an auditory feature (a tone) and a visual feature (a light) and non-reinforced in the presence of a compound stimulus that was either a noise and a dark key, or noise and a light. In the condition where reinforcement trials differed from non-reinforcement trials on the basis of both auditory and visual features, the tone exerted very little control over responding on test. In the condition where reinforcement differed from non-reinforcement trials solely on the basis of the auditory features, an abrupt and a gradual introduction of the visual feature of the negative stimulus, a light, were compared for their effect upon control in the compounds. The tone acquired strong control in both cases. Evidence indicated that the tone had acquired control in the gradual condition without the occurrence of responses to the negative stimulus. An incidental finding was that when the negative stimulus consisted of a noise and a light, which was introduced abruptly, responding over the light dimension with tone, on test, was peaked at a point other than that light value used as positive and negative during training.

Journal Article↗