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Biomedical subjects

D Kowalska

Publications and source records attributed to D Kowalska.

18 recordsLinked to original sources
PubMed1996

Investigation of the effect of Angelica sinensis root extract on the proliferation of melanocytes in culture.

Aqueous extracts of Angelica sinensis root, a herb commonly used in the treatment of vitiligo in Traditional Chinese Medicine, were tested for their activity on mouse melanocyte proliferation in culture. At concentrations of 0.5-2500 micrograms/ml, these extracts were not able to stimulate melanocyte cell division. On the contrary, they exerted a general cytotoxicity to the cells at higher concentrations. Cytotoxicity was reduced by prior treatment of the extract with polyvinylpolypyrrolidone, which was shown by thin layer chromatography to reduce the coumarin content.

Animals↗
PubMed1982

Stimulus control of instrumental reflexes in dogs: a comparison of alimentary and avoidance behaviors after prefrontal damage.

Two experiments involving parallel procedures to investigate stimulus generalization in prefrontal dogs under alimentary and defensive reinforcement were compared. Twelve dogs in the alimentary study were trained on a 50 percent partial reinforcement schedule, and 24 dogs were trained to avoid shock with either continuous shock availability and response contingent CS termination or with only 50 percent partial shock availability and response independent CS termination. One third of the subjects received bilateral medial prefrontal lesions, 12 dogs were given bilateral lesions of the lateral prefrontal cortex and the remaining subjects served as nonoperated controls. Generalization along the frequency dimension of the tonal CS was assessed during a sampling procedure within normal acquisition training, during complete extinction and following differentiation training. The results indicate specific effects from both the quality and the contingency of reinforcement. Within the limits of each reinforcement treatment, a dissociation occurred such that medial subjects tended to show heightened sensitivity to reinforcement density, while lateral subjects showed characteristic elevated reactivity during all generalization tests.

Animals↗
PubMed1981

Differentiation learning and auditory generalization in normal and prefrontal dogs after extensive avoidance training.

The continuation of a study of 24 dogs in the stages of avoidance reacquisition, differentiation training and generalization testing is reported. Subjects had previously received avoidance training with either response contingent CS termination on all trials or on only 50 percent of the training trials, prior to the administration of medial or lateral prefrontal lesions in 16 subjects. The remaining 8 subjects served as nonoperated controls. Following the appropriate surgical treatment, subjects were tested twice for generalization along the tonal frequency dimension of the avoidance CS. Trials to reacquisition criterion were comparable among all dogs, and subjects trained earlier with continuous response contingent CS termination had overlall faster response latencies, except for the medial subject that were slower than subjects trained under the partial schedule. Differentiation performance tended to show more success in the group given the earlier continuous response contingent avoidance training, although data from both training groups were variable. Subjects trained with the partial schedule had more extra- and intertial responses, which are considered as a byproduct of residual fear. Systematic effects from the surgical treatments were not found during differentiation training. Stimulus control by tonal frequency was more pronounced in subjects that had received the partial training schedule, and frequency generalization was disrupted by the lesion effects. The data are considered in light of reinforcement determinates from CS prolongation in the modification of defensive reflex control.

Animals↗
PubMed1979

Auditory frequency generalization in normal and prefrontal dogs trained in varieties of active avoidance reflexes.

Twelve dogs were trained to avoid shock with response contingent termination of a 1000 Hz tonal CS on all trials, whereas 12 additional dogs received the same training except that on 50 percent trials there was a fixed CS duration and no shock. Initial acquisition revealed that CS prolongation resulted in longer response latencies compared to subjects trained with response contingent CS termination. Both training groups were then assigned to subgroups (n=4) that received either lateral or medial lesions of the prefrontal cortex or a rest pause of 10 days. Postsurgical reacquisition indicated a medial deficit in response latencies for both training groups whereas performance levels of normal and lateral groups were comparable. Two generalization tests to tones of 600-, 800-, 1000-, 1200-, and 1400-Hz followed. During the sampled test only one block of the five test frequencies occurred with the regular 15 training trials, while the tonal frequencies were presented on all 20 daily extinction trials during massed generalization testing. No evidence of extinction was observed during the sampled generalization test in either training group. However, during massed testing, all subjects trained with response contingent CS termination showed an overall extinction influence, which was most pronounced in the medial subgroup, although the laterals showed frequency control as well. In the group trained with CS prolongation the controls had clear, discriminative performance, while little stimulus control or extinction influence were found in the medial or lateral subgroups. Comparison with alimentary data indicated much broader tonal frequency generalization in dogs trained in avoidance. However, when the procedures reduced avoidance levels, double dissociation of medial and lateral lesion effects on stimulus control and susceptibility to extinction emerged.

Acoustic Stimulation↗
PubMed1976

Auditory frequency generalization with differing extinction influences in normal and prefrontal dogs trained in instrumental alimentary reflexes.

Following criterion of 90 percent correct responses to a 1,000-Hz tone on a 50 percent reinforcement schedule, 8 of 12 dogs were subjected to lesions of the medial or lateral prefrontal cortex. Three types of auditory frequency generalization tests followed separated by a period of reacquisition of the instrumental response. A sampling procedure of generalization assessment, wherein a block of test trials was contained within 15 partially reinforced trials and repeated over 16 days, revealed complete generalization in the medials and rapid, but discriminative responding in the laterals. The second generalization test was conducted in complete extinction over 5 days. The medials yielded discriminative performance and least overall resistance to extinction, while the laterals showed a higher amount of frequency control and minimal extinction effects. Go-no go differentiation training preceeded the last generalization test [CS(+) = 1,000 Hz; CS(-) = 600 Hz], resulting in retarded acquisition in the laterals and easiest acquisition in the medials. The last generalization test suggested that all groups were comparable, with some trend toward more rapid extinction in the medial dogs. Collectively, the data indicated that performance was determined by the interacting functions between the specific lesions and the density of reinforcement present in the testing procedure.

Animals↗
PubMed1975

Effects of partial prefrontal lesions in dogs on go-no go avoidance reflex differentiation and reversal learning.

The effects of prefrontal medial or lateral lesions on the retention of avoidance go – no go click-tone differentiation in dogs were studied. The acquisition of the differentiation was influenced by the quality of the stimuli since more errors were performed to the click CS(-) than to the tone CS(-). Neither medial nor lateral lesions exerted any effect on retention of the differentiation. Similarly, as during original differentiation training, the quality of the stimuli had an effect on reversal learning in normal dogs. Such an effect was markedly reduced in dogs with prefrontal lesions and more strongly in those Ss which received lateral lesions. The results were discussed relative to data obtained from cats trained under similar conditions. The dogs showed better responding on positive trials while performance in cats was better on negative trials. The stimulus quality effect was more pronounced in dogs during negative, and in cats during positive trials.

Animals↗