Psychological testing, IQ, and evolutionary fitness.

Individual group, and ethnic differences in behavior have been an object of long, continuing, and contentious interest, both in the sciences and in popular culture. For well over 2,000 years, psychological traits, particularly those described as 'intelligence', have generally been considered the major factors in fitness in humans. After reviewing contemporary scientific thinking on intelligence, the psychometric methods used for the construction of psychological tests are presented and examined in the context of natural selection and metric characters. There are essential differences between the disciplines of genetics and of psychology such that the concepts of the two are more divergent than might superficially appear to be the case. The analysis leads to the conclusion that standard psychometric methodology cannot yield tests appropriate for measurement of evolutionary fitness characters.

Quantitative coronary arteriography and its assessment of atherosclerosis. Part I. Examining the independent variables.

BACKGROUND: Previous work has demonstrated that quantitative coronary arteriography (QCA) can accurately measure phantom images to within +/- 0.1 mm and has been accepted as a reliable and reproducible method of measuring human coronary artery disease (CAD). Assessment of CAD by QCA involves the measurement of numerous variables, which are currently required to calculate stenosis flow reserve (SFR). METHODS AND RESULTS: In this study 1040 stenotic lesions were analyzed by two well-accepted methods with demonstrated accuracy and reproducibility. These methods measure percent diameter stenosis (%DS), absolute diameter, percent area stenosis, length, as well as entry and exit angles to and from a stenotic coronary artery lesion respectively. Based upon these results, the mean +/- standard deviations and range seen in CAD were determined for each of these independent variables. This study demonstrated that atherosclerotic coronary artery lesions do not appear to exceed an entry angle of -39 degrees, and exit angle of +35 degrees, or an absolute length of 4.84 cm when accurately measured by QCA. It was also noted that, once percent diameter stenosis exceeded 89% (regardless of the visual estimate) or percent area stenosis exceeds 99%, coronary arteries become completely occluded as measured by QCA. CONCLUSIONS: While previously suspected that once certain critical limits are exceeded in the deposit of cholesterol and calcium within the coronary artery, the artery will close, this study demonstrated by QCA what the limitations in human coronary arteries appear to be. These limits may be in part due to turbulent factors resulting in platelet activation or local mediators from endothelium of the coronary artery.

Quantitative coronary arteriography and its assessment of atherosclerosis. Part II. Calculating stenosis flow reserve from percent diameter stenosis.

BACKGROUND: Assessment of coronary artery disease by quantitative coronary arteriography (QCA), while highly accurate, is more expensive than visual estimates of disease and involves the measurement of numerous variables requiring specialized equipment and personnel, thereby reducing its clinical applicability. In part 1 of this paper, the independent variables that influence flow of 1040 coronary artery segments were analyzed. METHODS AND RESULTS: Using the information previously reported in part 1 of this paper, we set out to determine the importance of each of the independent variables (percent diameter and area stenosis, length, absolute diameter, entry and exit angles) in the prediction of stenosis flow reserve (SFR). Analysis of variance (ANOVA) was used to determine the importance of each of these variables, as well as their interactions, on the determination of SFR. Only percent diameter stenosis (%DS) demonstrated statistical significance (P < 0.001) in determining stenosis flow reserve. When the results of SFR were plotted against %DS, a quadratic relationship was demonstrated with an R2 value of 0.903 (r = 0.95). To verify the quadratic equation, the %DS of 100 different arterial stenoses was measured and used to calculate an SFR by the quadratic formula. The QCA and quadratic (calculated) determined SFRs compared favorably, with a correlation of 0.97. CONCLUSIONS: The ability to calculate SFR directly from measured %DS allows the incorporation of calculated SFR into the clinical setting, where cardiologists can interpret lesion severity both anatomically and hemodynamically. This incorporation can be done without additional cost to the physician, hospital, patient, or third-party payers.

Conflict behavior in Maudsley reactive and nonreactive rats: effects of noradrenergic neuronal destruction.

The present studies were designed to examine the effects of treatment with the noradrenergic neurotoxin N-(2-chloroethyl)-n-ethyl-2-bromobenzylamine HCl (DSP4; 65 mg/kg, IP) on conflict behavior in the Maudsley reactive (MR) and nonreactive (MNRA) rat strains. In daily 10-min sessions, water-restricted rats were trained to drink water from a tube that was occasionally electrified; electrification was signaled by the presence of a tone (7-s duration; ISI = 30 s). Consistent with previous reports, the number of shocks accepted by rats of the MR and MNRA strains did not differ initially, but MNRA rats exhibited a dramatic increase in punished responding relative to their MR counterparts over the course of several weeks of conflict testing. This MR vs. MNRA strain difference in punished responding did not exhibit extinction following discontinuation of CSD conflict behavior testing for a period of 6 weeks. Whether it was administered after conflict training or before, DSP4 treatment did not reduce the MR vs. MNRA strain difference in conflict behavior; rather, DSP4 treatment tended to increase the magnitude of the MR vs. MNRA difference in conflict behavior. The effects of DSP4 on norepinephrine (NE) and 5-hydroxytrypamine (5-HT) concentrations in the pons medulla region were determined in one group of conflict-experienced MR and MNRA rats (35 weeks after administration) and in a second group of naive MR and MNRA rats (3 weeks after administration). There were no MR vs. MNRA strain differences in NE or 5-HT concentrations in vehicle-treated rats. DSP4 treatment significantly reduced NE, but not 5-HT, concentrations when compared to control values; rats that were sacrificed 3 weeks following DSP4 administration exhibited a greater NE depletion than did rats sacrificed 35 weeks after DSP4 administration. Finally, there were no significant correlations between pons medulla region NE concentrations and conflict behavior in either strain alone or when the data from the two strains were combined. The present results are not consistent with the hypothesis that the MR vs. MNRA strain difference in conflict behavior is the result of strain differences in brain NE function.

Benzodiazepine anti-conflict effects in Maudsley reactive (MR/Har) and non-reactive (MNRA/Har) rats.

The Maudsley Reactive (MR/Har) and Non-Reactive (MNRA/Har) rat strains, bred originally by Broadhurst for differences in Open Field Defecation, also differ in their control (i.e., non-drug) behavior in the Conditioned Suppression of Drinking (CSD) conflict procedure, a second "model" behavior for the study of anxiety and/or emotionality in rats. The present studies compared the effects of diazepam and alprazolam on CSD behavior in these two strains of rats. In daily 10-min sessions, water-deprived rats were trained to drink from a tube that was occasionally electrified (0.2-0.5 mA), electrification being signaled by a tone. Both diazepam and alprazolam increased punished responding in a dose-related manner. The per cent increase in punished responding (for diazepam only) was comparable in the two strains; however, both statistical and empirical approaches indicated that the magnitude of the anti-conflict effect of benzodiazepines in MNRA/Har versus MR/Har rats was not related to differences in baseline (i.e., non-drug) punished responding. Based on the absolute change in shocks received, rats of the MNRA/Har strain exhibited a significantly greater anti-conflict effect following diazepam or alprazolam treatment than did rats of the MR/Har strain. These findings further the hypothesis that the behavioral differences exhibited by Maudsley MR/Har and MNRA/Har rat strains may constitute a genetically-based "animal model" for the study of emotionality and/or anxiety.

MR/Har and MNRA/Har Maudsley rat strains: differential response to chlordiazepoxide in a conflict task.

The Maudsley Reactive (MR/Har) and Non-Reactive (MNRA/Har) rat strains, selectively bred for differences in open field defecation, have also been shown to differ in their baseline behavior in the Conditioned Suppression of Drinking (CSD) procedure, a second "model" behavior for the study of anxiety and/or emotionality in rats. The present studies were designed to compare the responsiveness of these two strains to the typical antianxiety agent chlordiazepoxide in the CSD paradigm. In daily 10-minute sessions, water-deprived rats were trained to drink from a tube that was occasionally electrified (0.5 mA), electrification being signaled by a tone. Consistent with previous reports, after several weeks of CSD testing, MNRA/Har rats accepted significantly more shocks than did MR/Har rats during control (nondrug) sessions. In both strains, the number of shocks accepted was inversely related to the intensity of the shock used (0.25-1.0 mA), with MNRA/Har rats accepting significantly more shocks than MR/Har rats at all intensities examined. The effects of various doses (1.25-28.4 mg/kg, IP) of chlordiazepoxide were determined in subjects of the MNRA/Har strain at the original training intensity (0.5 mA), while a lower intensity (0.25 mA) was utilized in MR/Har rats. Although punished responding in control (i.e., nondrug) CSD sessions did not differ under these conditions, MNRA/Har rats were found to be more responsive to the anticonflict effects of chlordiazepoxide than rats of the MR/Har strain. This strain difference in anticonflict efficacy of chlordiazepoxide was quite dramatic, with MNRA/Har rats accepting twice as many shocks as MR/Har rats following maximally effective doses of chlordiazepoxide. Low doses of chlordiazepoxide increased water intake slightly, while higher doses decreased water intake. Surprisingly, the chlordiazepoxide-induced depression of water intake was greater in rats of the MR/Har strain. Thus, these Maudsley Reactive and Non-Reactive rat strains, bred originally for their differences in open field behavior, also differ markedly in their responsiveness to chlordiazepoxide in the CSD paradigm. These findings further support the hypothesis that the MR/Har and MNRAHar rat strains may represent a genetically-based "animal model" for the study of emotionality and/or anxiety.

Defensive burying behavior in maudsley reactive (MR/Har) and nonreactive (MNRA/Har) rats.

Based upon differences in open field and conflict behaviors, the MR/Har and MNRA/Har rat strains have been proposed as a genetically-based "animal model" for the study of emotionality and/or anxiety. The present study compared the MR/Har and MNRA/Har rat strains in the Defensive Burying paradigm. Prior to testing, female MR/Har and MNRA/Har rats were placed in a 40 X 30 X 40 cm Plexiglas chamber containing clay bedding material (5 cm deep) for 30 minute periods on each of four consecutive days. On the fifth day, a wire wrapped prod was placed at one end of the chamber. Rats were placed in the chamber singly and a 3 mA shock was delivered upon contact with the prod. Defensive Burying behavior (i.e., the moving of bedding material toward or over the prod) was recorded for each animal for 15 minutes postshock. There was no MR/Har versus MNRA/Har difference in the percent of animals exhibiting Defensive Burying, nor was there a MR/Har versus MNRA/Har difference in the latency to initiation or the duration of this behavior. Thus, these genetically-defined Maudsley rat strains do not appear to differ in all "animal models" for the study of anxiety or fear.

Two forms of minority-group test bias as psychometric artifacts with an animal model (Rattus norvegicus).

Controversy abounds over attributing group differences on tests to nature, nurture, or test bias. Limitations of correlational sampling from natural populations necessitate experimental methods to resolve underlying issues. In classical psychometrics test items are selected from a larger item pool through analysis of item responses in a sample of subjects. Rats of six inbred strains (n = 366) were tested in multiple mazes to provide a large item pool. Six populations were created, each with differing proportions of each strain. Items selected through independent item analyses within each population yielded six tests. An independent cross-validation sample (n = 146) provided scores on all six tests. This sample was also tested in another set of maze problems defined as the criterion to be predicted. Strain means and intrastrain predictive validities for the six tests varied with strain representation in the population used for item selection (p less than .001). Conventional item-selection procedures clearly produced two forms of minority test bias.

Maudsley reactive and non-reactive rat strains: differential performance in a conflict task.

Based on open field defecation rates, distinct strains of Maudsley rats have been identified. The Maudsley Reactive strains exhibit high levels of open field defecation, while the Maudsley Non-Reactive strains exhibit low levels of open field defecation. This difference in open field behavior has been interpreted as an indicator of "emotionality." The present studies were designed to compare the performance of two Maudsley strains, MR/Har and MNRA/Har, in the conditioned suppression of drinking (CSD) paradigm, another "model" behavior for the study of emotionality and/or anxiety in animals. In daily 10-minute sessions, water-deprived rats were trained to drink from a tube that was occasionally electrified (0.5 mA), electrification being signalled by a tone. In this procedure, MNRA/Har rats accepted significantly more shocks than did MR/Har rats. This difference between MR/Har and MNRA/Har strains, initially somewhat slight, became quite impressive over weeks of repeated testing. Although present in both male and female subjects, this strain difference was more prominent in the males. Thus, the MR/Har and MNRA/Har rat strains, bred originally for their differences in open field behavior, also differ markedly in their performance in the CSD paradigm. These findings suggest that the Maudsley rat strains may represent a useful genetically-based "animal model" for the study of emotionality and/or anxiety.

The Har strains of rats: origins and characteristics.

Origins of the principal lines of Rattus norvegicus used in behavior genetic research are identified. Broad descriptions are provided for 15 of the Har strains and substrains of well-established inbred lines and behaviorally selected stocks. Marker genes are identified for coat and major histocompatibility complex (MHC) loci. Detailed characteristics are summarized for 12 of these lines using a comprehensive behavioral test battery composed of a variety of measures of expressive behavior, learning, and physiological characteristics.