Serotonergic and opiate interactions in the modulation of drug- and environmental-induced analgesia in the neonatal rat pup

Serotonergic and opiate interactions in the modulation of drug- and environmental-induced analgesia were assessed in 6-day-old Sprague-Dawley-derived rat pups using tail-flick testing procedures. In these experiments the serotonergic antagonist metergoline was observed to attenuate both the analgesia induced by the opiate agonist morphine and the analgesia induced by isolation from siblings and the dam, an environmental manipulation which has previously been shown to be associated with increases in opiate activity. In contrast, the opiate antagonist naloxone was observed to be ineffective in blocking not only analgesia induced by the serotonergic agonist quipazine, but also analgesia induced by long-term deprivation from the dam and food, a manipulation that has been previously reported to induce increases in serotonergic utilization. These results suggest that in the neonate, as in the adult, the serotonergic modulation of nociception appears to occur "downstream" from the opiate systems serving to regulate nociception following both drug- and environmental-induced alterations in pain sensitivity. Analgesia induced by long-term deprivation from food and the dam appears to be strongly related to increases in serotonergic activity and relatively unaffected by opiate antagonism, whereas analgesia induced by isolation from siblings and the dam may be related to increases in opiate activity, but modulated by serotonergic systems serving to regulate pain responsivity. Thus alterations in the environment, mediated at least in part by alterations in opiate and serotonergic activity, appear to play an important role in influencing the sensitivity of the neonate to pain stimuli.     

Dissociation of data-based and expectancy-based memory following hippocampal lesions in rats

Sham-operated and nonoperated animals or animals with hippocampal lesions were presented with sets of trials to test both expectancy-based and data-based memory within the same task. During the study phase of each trial the animals were presented with a constant sequence of five arms on an eight-arm radial maze followed by a test phase in which a recognition test requiring a win-stay rule was used. Expectancy-based memory was measured during the study phase of the trials as a pattern of correct or incorrect orienting responses in anticipation of the ensuing doors in the constant sequence. Both groups of animals acquired correct orienting responses at the same rate, emitted the same pattern of correct orienting responses, and made the same number and pattern of intralist and extralist intrusion errors. Data-based memory was measured during the test phase of the trial as correct recognition test performance. During the test phase the animals with hippocampal lesions were impaired relative to controls on both immediate and 24-h recognition tests. These results suggest that the hippocampus might mediate only data-based, but not expectancy-based, memory and imply a possible dissociation between expectancy-based and data-based memory systems.     

Strength of scopolamine-induced amnesia as a function of time between training and testing

Variations in the strength of scopolamine-induced amnesia as a function of age of the habit were studied in Swiss Webster mice. Animals were trained in an active avoidance task to a criterion of 9/10 avoidances and immediately following training injected with scopolamine hydrochloride (1.0 mg/kg) or saline. Retention of the avoidance learning was evaluated by testing different groups of animals 1, 3, 7, 10, 14, and 28 days following training. The retention test consisted of five trials in which the CS but not the UCS was presented. Results indicated that saline-treated mice exhibited near-perfect retention up to 14 days post-training with forgetting beginning to be apparent at 28 days. Scopolamine treatment produced strong amnesia in animals tested 1 and 3 days post-training but normal retention in animals tested 7 and 10 days after learning. The amnesia abruptly reappeared at 14 days after which time it remained stable. The marked similarity of the scopolamine retention curve to changes in the strength of memory of discrimination learning in undertrained rats reported by Deutsch suggested that scopolamine resulted in the storage of a weak memory of the avoidance response. To explore this idea further we trained mice to a criterion (4/5) which would result in a weak avoidance response and tested different groups 1, 3, 10, 14, and 28 days following learning. Results showed that strength of the memory of avoidance learning increased up to 10 days and then decreased abruptly at 14 days thus replicating the general shape of the retention curve produced by injecting scopolamine following strong training. These data suggest that scopolamine disrupts processes essential for the formation of durable memories.     

Memory and awareness in a patient with multiple personality disorder

We studied an individual with multiple personality disorder in whom each of several personalities claimed to have no direct awareness of the others and to be unable to consciously remember the experiences of other personalities. A broad selection of implicit and explicit memory tests was used to determine the extent to which one personality had access to knowledge acquired by another and the circumstances in which that knowledge would be expressed. The implicit assessment of memory was a necessary but not sufficient condition for demonstrating interpersonality access. The degree of compartmentalization of knowledge in this patient depended largely on whether the interpretation of presented information was likely to differ across personalities.     

Subject knowledge of the Experimenter''s interest in handedness and familial sinistrality variables and laterality test outcomes

We investigated the possible influence of common "demand characteristics" on the results on behavioral language laterality tasks. The demand characteristics were (1) whether Ss were or were not recruited for study according to their handedness, and (2) whether a detailed familial sinistrality inquiry was conducted before or after the tasks. Tasks were the Dichotic Consonant Vowel Task (DCVT) and the Bilateral Object Naming Latency Task (BONLT). Results showed no effect of demand characteristics on the BONLT. On the DCVT, however, prior inquiry regarding familial sinistrality was associated with significantly reduced right ear advantages (REAs). Interactions showed that the greatest reduction in REAs occurred in Ss with left-handedness in their families, who were asked about familial sinistrality prior to the tasks, who took the DCVT after the BONLT, and who were also recruited by handedness. Results, though generally reassuring regarding the robustness of the tasks against these sources of bias, raise some cautions for the DCVT.     

Assessment of methods for measuring social support

A rapidly expanding literature documents the effects of social support on physical and psychological well-being. Although definitions vary, most include both tangible components (e.g., financial assistance and physical aid) and intangible components (e.g., encouragement and guidance). Social support has been implicated in the mediation of stressful life events, recovery from illness, and increased program adherence. There are many inconsistent findings in the literature, however, and it is difficult to resolve discrepancies because measures of social support vary widely from study to study. To guide in the selection of measurement methods for research and applied work, 23 techniques for assessing social support are reviewed and evaluated. Criteria for favorable evaluation included reliability coefficients greater than .8 and documentation of validity. Correlations between various social support and criterion measures are simulated in order to demonstrate the consequences of choosing a measure with low reliability. Scale developers reported reliability data for 19 of the reviewed measures. Internal consistency coefficients ranged from .31 to .98. Test-retest coefficients ranged from .22 to .96. At least some validity documentation was available for 13 of the scales. Discriminant validity evidence, however, is almost universally absent. Despite psychometric weaknesses and variability among the scales, researchers have several instruments available to them.     

Knowledge and beliefs regarding the consequences of cigarette smoking and their relationships to smoking status in a biracial sample

The purpose of this investigation was to evaluate carefully smoking-related knowledge and beliefs and their relationships to smoking status in a large, heterogeneous sample of smokers and nonsmokers in two settings: (a) a large, biracial southern city and (b) a small midwestern community. Participants were 611 (198 male, 413 female) adult respondents to a random-dialing telephone survey in Fargo, North Dakota (n = 200), and Memphis, Tennessee (n = 411). Each participant was given the Smoking Attitudes Survey, which assesses generalized health beliefs as well as health-related problems associated with smoking. Participants' knowledge of smoking-associated diseases (e.g., lung cancer) and of diseases not associated with smoking (e.g., kidney stones) was assessed. Stepwise regression analysis of composite knowledge scores revealed four independent predictors of the health consequences of smoking: education, race, smoking status, and income. Smokers, compared to nonsmokers, reported less knowledge related to the health consequences of smoking, were more likely to be male, were less concerned with the health consequences of smoking, and were more concerned about the health consequences of cholesterol. The best predictor of smokers who had never attempted cessation was their greater concern over weight control when compared to smokers with a history of smoking cessation attempts. The results are discussed in terms of smoking prevention and intervention efforts.     

Exercise as a buffer of life stress: a prospective study of adolescent health

The hypothesis that physical exercise provides benefits to individuals under periods of life stress has rarely been subject to empirical verification. This article presents the results of a longitudinal study of stress and well-being in adolescence in which the ability of exercise to buffer stress-induced deteriorations in physical health was examined. In accordance with predictions, prospective analyses revealed that the negative impact of stressful life events on health declined as exercise levels increased. These findings suggest that exercise may be a valuable resource for combating life stress. Discussion centers on possible mediating mechanisms and on the practical implications of the results.     

Studies of psychosocial influences on coronary artery atherogenesis in cynomolgus monkeys

The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described.     

Smoking, caffeine, and stress: effects on blood pressure and heart rate in male and female college students

This study examined the independent and joint effects of cigarette smoking and caffeine consumption on blood pressure (BP) and heart rate (HR) reactions to stress in male and female college students. Following an initial physiological baseline, participants received one of four experimental treatments (paced smoking, caffeine, smoking plus caffeine, or neither) and had BP and HR measured before, during, and after two stressful tasks. The results revealed that, compared with the control condition, caffeine ingestion enhanced the magnitude of stress-induced systolic BP and HR reactions. Smoking combined additively with stress, and the joint effect of smoking and caffeine was no greater than either taken alone. Males and females were generally similar in their BP and HR responses to smoking, caffeine, and stress. Inconsistencies with previous research and possible physiological mechanisms underlying the observed effects are discussed.