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Biomedical subjects

J M Pearce

Publications and source records attributed to J M Pearce.

At least 91 records · Page 5Linked to original sources
PubMed1996

Duane's syndrome.

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Duane Retraction Syndrome↗
PubMed1995

Effects of context on responding during a compound stimulus.

In 4 experiments, the authors used rats to examine the strength of responding during a clicker-tone compound in the presence of a light, after the auditory stimuli had individually been paired with food in the presence of the same light. Experiment 1 demonstrated a higher rate of responding during the compound when the duration of the light was short rather than long. In Experiments 2, 3, and 4, the long duration light was used as a signal for food in a conditional discrimination involving the tone and the clicker. Responding on test trials with the clicker-tone compound during the light was enhanced by this treatment and resulted in a level of performance that was no different from that observed when the duration of the light was short. The results are more compatible with a configural than an elemental theory of associative learning.

Animals↗
PubMed1995

Cervicogenic headache: a personal view.

Cervicogenic headache describes pain referred along the upper three cervical roots and is a common source of headache in the over fifties. A review of clinical features, anatomy, and investigations using neural blockade shows several clinical pictures. Diseases of the cranio-vertebral junction, e.g. syringomyelia, and tonsilar descent, can produce mechanical or hydrodynamic head and neck pain. Pre-existent migraine and tension headache may be precipitated or aggravated by cervical spondylosis, but the anatomical mechanism is unclear. Headaches which arise from and are primarily caused by disorders in the cervical spine are exemplified by spondylosis and acute whiplash injury, but are usually transient. Evidence for a cervicogenic mechanism of chronic whiplash headache is, however, lacking.

Cervical Vertebrae↗
PubMed1995

Charcot joints.

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Arthropathy, Neurogenic↗
PubMed1995

Supernormal conditioning.

In Experiment 1, rats received an A+AX degrees discrimination in which food was presented after Stimulus A by itself but not after a simultaneous compound of A with Stimulus X. AX was then paired with food in a 2nd stage, followed by test trials with A alone. Responding on the test trials with A was more vigorous than during a control stimulus that had been consistently paired with food. The remaining experiments were of similar design to Experiment 1, except that the 2nd stage also contained conditioning trials with X. The results from the test trials were essentially the same as for Experiment 1. The high level of responding during the test trials with Stimulus A is regarded as evidence of supernormal conditioning. Overall, the results are more consistent with a configural than an elemental theory of conditioning.

Animals↗
PubMed1995

Stimulus salience and negative patterning.

Rats in Experiment 1 received a negative patterning discrimination in which food was delivered after either of two auditory stimuli when they were presented individually, but not when they were presented in compound. The stimuli were of different intensity. The discrimination between the compound and the stimulus of lower intensity was acquired more readily than was the discrimination between the compound and the more intense stimulus. A similar pattern of results was found in the remaining two experiments, which also employed a negative patterning discrimination, but either with stimuli from different modalities (Experiment 2) or with pigeons rather than rats (Experiment 3). The results were predicted more readily by a configural than by an elemental theory of conditioning.

Animals↗
PubMed1995

The placebo enigma.

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Anti-Anxiety Agents↗
PubMed1994

Transmission of varicella-zoster virus from a vaccinee with leukemia, demonstrated by polymerase chain reaction.

A 5-year-old white boy in remission from acute lymphoblastic leukemia who was receiving maintenance anticancer chemotherapy had approximately 200 vesicular skin lesions 1 month after receiving live attenuated varicella vaccine. About 2 to 3 weeks later, a mild illness resembling varicella occurred in his susceptible siblings and in three of his classmates. Vaccine-type varicella-zoster virus was demonstrated by polymerase chain reaction in swab specimens from vesicular lesions in his two siblings, in whom antibody to varicella-zoster virus also developed.

Chickenpox↗
PubMed1994

Similarity and discrimination: a selective review and a connectionist model.

The 1st part of this article evaluates the extent to which 2 elemental theories of conditioning, stimulus sampling theory and the Rescorla-Wagner (1972) theory, are able to account for the influence of similarity on discrimination learning. A number of findings are reviewed that are inconsistent with predictions derived from these theories, either in their present form or in various modified forms. The 2nd part of the article is concerned with developing an alternative, configural account for discrimination learning. In contrast to previous configural theories, the present version is set within the framework of a connectionist network.

Animals↗