A comparison of intradimensional and extradimensional shift learning in pigeons

In each of three experiments pigeons were trained on a simultaneous discrimination between stimuli that differed in both colour and orientation. For half the birds the colour dimension was relevant and for half orientation was relevant (i.e., differences along that dimension were correlated with reward and nonreward). All birds were then shifted to a second discrimination between new colours and orientations. For half this constituted an intradimensional shift in that the previously relevant dimension remained relevant; for the remainder the previously irrelevant dimension was made relevant (an extradimensional shift). Contrary to the predictions of attentional theory, the two types of shift were learned with equal ease.

Measurement of behavioral, affective, and somatic responses to pediatric bone marrow transplantation: development of the BASES scale

A new measure to assess behavioral, affective and somatic outcomes in the acute phase of bone marrow transplant is described. The Behavioral Affective and Somatic Experiences Scale (BASES) is a 38 item nurse-report instrument, with five subscales labeled Somatic distress, Compliance, Mood/Behavior, Interactions, and Activity. A series of pilot studies were conducted to refine the content of the BASES scale and to establish its psychometric properties in terms of internal consistency, inter-rater reliability, and validity. Internal consistency (Chronbach's alpha) for the subscales ranged from .742 to .902. Inter-rater reliability was good, with a median correlation between paired nurse observations of .866. A parent report version of the BASES scale has also been developed, and the finding of significant parent-nurse correlations provides preliminary evidence of the validity of the measure. Potential uses of the BASES scale in the pediatric BMT setting are discussed.

A comparison of the effects of the novel muscarinic receptor agonists L-689,660 and AF102B in tests of reference and working memory

Four experiments compared the CNS effects of a novel M1/M3 receptor agonist L-689,660 with those of the M1/M3 muscarinic receptor agonist AF102B. In the mouse tail-flick test of antinociception (TF) the minimum effective doses to increase tail-flick latency (MED) of L-689,660 and AF102B were 0.03 mg/kg and 10.0 mg/kg, respectively. In a rat conditioned-suppression-of-drinking (CSD) test of reference memory, doses of 0.3 and 1.0 mg/kg L-689,660 and a dose of 5.0 mg/kg AF102B reversed a scopolamine-induced deficit in performance (0.6 mg/kg). Although there was a tendency for L-689,660 to reverse the scopolamine-induced (0.4 mg/kg) performance deficit in a rat delayed-matching-to-position (DMTP) test, the difference failed to reach statistical significance. In contrast, a 5.0 mg/kg dose of AF102B potentiated the scopolamine-induced deficit in choice accuracy and the number of trials completed on this task. In a response sensitivity (RS) test, chain-pulling rates were significantly decreased by L-689,660 (MED = 0.03 mg/kg) and by AF102B (MED = 5.0 mg/kg). These results suggest that L-689,660 and AF102B may ameliorate or reverse a scopolamine-induced deficit, but only at doses that also reduce chain-pulling rates on operant schedules of reinforcement.

Response-reinforcer associations after caudate-putamen lesions in the rat: spatial discrimination and overshadowing-potentiation effects in instrumental learning

Experiment 1 demonstrated that rats with caudate-putamen lesions show an impairment in the acquisition and reversal of a spatial maze task when compared with unoperated control subjects. Experiment 2 examined lever-press responding supported by a variable interval schedule in three groups of subjects: a group with caudate-putamen lesions, a group with lesions of the posterior cortex, and an unoperated control group. The presentation of a 0.5-s, response-contingent light correlated with reinforcement generated an elevated response rate in the two operated groups but tended to suppress responding in the control group, perhaps by overshadowing the response-reinforcer relation. Only the group with cortical lesions maintained the elevated rate when the light was uncorrelated with food delivery. Experiment 3 confirmed for these same subjects that caudate-putamen lesions produce a spatial learning deficit. No deficit was seen in the posterior cortex group. It is suggested that caudate-putamen lesions disrupt the mechanism underlying the response-reinforcer association upon which spatial maze learning and free operant responding in part depend.

Response–reinforcer associations after caudate-putamen lesions in the rat: Spatial discrimination and overshadowing–potentiation effects in instrumental learning

Experiment 1 demonstrated that rats with caudate-putamen lesions show an impairment in the acquisition and reversal of a spatial maze task when compared with unoperated control subjects. Experiment 2 examined lever-press responding supported by a variable interval schedule in three groups of subjects: a group with caudate-putamen lesions, a group with lesions of the posterior cortex, and an unoperated control group. The presentation of a 0.5-s, response-contingent light correlated with reinforcement generated an elevated response rate in the two operated groups but tended to suppress responding in the control group, perhaps by overshadowing the response-reinforcer relation. Only the group with cortical lesions maintained the elevated rate when the light was uncorrelated with food delivery. Experiment 3 confirmed for these same subjects that caudate-putamen lesions produce a spatial learning deficit. No deficit was seen in the posterior cortex group. It is suggested that caudate-putamen lesions disrupt the mechanism underlying the response-reinforcer association upon which spatial maze learning and free operant responding in part depend.

Stimulus exposure and discrimination in rats: a test of a theory for the role of contextual factors

In two experiments rats were trained on a simultaneous discrimination in a jumping stand. On each trial choice always lay between one stimulus (an obliquely striped object in Experiment I, and a plain grey object in Experiment II) and a second that varied from trial to trial. On half the trials this variable stimulus bore horizontal stripes (H) and on the remaining trials it bore vertical stripes (V). It was argued that the solution of this discrimination would be hindered if the animals tended to classify H and V apart (Bateson and Chantrey, 1972). It was found, however, that prior exposure to H and V in the home cage (which has been supposed to promote classifying apart) facilitated learning and that prior exposure to H and V in the apparatus itself (which might be thought to promote classifying together) hindered later learning. Possible alternative accounts for these exposure learning effects are discussed.

Facilitation and retardation of discrimination learning after exposure to the stimuli

In three experiments, rats was required to learn a simultaneous discrimination in a jumping stand between horizontally and vertically striped objects. Experiment 1 showed that prior prolonged exposure to these stimuli in the rats' home cages helped them to learn the discrimination. Experiment 2 showed that a briefer period of exposure (1 hr per day for 50 days) was equally effective when the stimuli were presented in the home cage but produced a retardation of discrimination when the stimuli were presented in the jumping stand itself. Experiment 3 demonstrated that prior exposure to the jumping stand was not in itself enough to produce a retardation of subsequent discrimination learning. Some implications of these results for current theories of perceptual learning and latent inhibition are discussed.

A search for perceptual differentiation produced by nondifferential reinforcement

In each of four experiments (three using pigeons as the subjects and one using rats) animals in an experimental condition were given exposure to a pair of stimuli that subsequently they were required to discriminate between. During the exposure phase response to either stimulus was consistently followed by reward. These subjects were uniformly found to be retarded in learning the discrimination when compared with control subjects that received equivalent pre-training in the absence of the critical stimuli. These results provide no support for the suggestion that stimuli may become “perceptually differentiated” during the pre-training phase but are consistent with the proposal that novel stimuli possess a high level of associability that declines as a result of experience.

Allergic alveolitis in a maltworker

A further example of diffuse pulmonary hypersensitivity to an inhaled organic antigen is reported. A 42-year-old maltworker, who developed an illness resembling farmer's lung, was found to have been heavily exposed to the spores of Aspergillus clavatus. Precipitating and complement-fixing antibodies against an extract of A. clavatus were detected in his serum, a late (Arthus-type) reaction was produced by intradermal injection of the same extract, and a pyrexial reaction, accompanied by a reduction in forced vital capacity and carbon monoxide transfer factor, occurred 6 hours after the inhalation of spores of A. clavatus. Two of the patient's four workmates complained of similar but less severe symptoms, and their sera also contained specific antibodies. Although the spores of A. clavatus and of Cryptostroma corticale, the fungus responsible for maple-bark disease, are much larger than the 1 μ spores of Micropolyspora sp., they may give rise to a diffuse pulmonary hypersensitivity reaction indistinguishable from that observed in farmer's lung. This suggests that the occurrence of such a reaction is not necessarily related to the size of the inhaled particles, and there is reason to believe that the concentration of spores or other antigenic particles in the inspired air may in this respect be more important than their size. The pulmonary hypersensitivity in this group of disorders appears to be a precipitin-mediated (type III) response to a variety of inhaled antigens, but some of these antigens may in certain patients, presumably atopic individuals, also provoke a reagin-mediated (type I) bronchial hypersensitivity reaction. It is suggested that a term such as `allergic alveolitis' or `extrinsic allergic alveolitis' may suitably be used to describe the group of diseases caused by pulmonary hypersensitivity to inhaled organic antigens.