Daily mood patterns and bulimic behaviors in the natural environment

Objective

Negative affect has been purported to play an important role in the etiology and maintenance of bulimic behaviors. The objective of this study was to identify daily mood patterns in the natural environment exhibited by individuals with bulimia nervosa and to examine the relationship between these patterns and bulimic behaviors.

Method

One hundred thirty-three women aged 18-55 meeting DSM-IV criteria for bulimia nervosa were recruited through clinical referrals and community advertisements. Ecological momentary assessment was used to collect multiple ratings of negative affect, binge eating and purging each day for a two-week period using palmtop computers. Latent growth mixture modeling was used to identify daily mood patterns.

Results

Nine distinct daily mood patterns were identified. The highest rates of binge eating and purging episodes occurred on days characterized by stable high negative affect or increasing negative affect over the course of the day.

Conclusions

These findings support the conclusion that negative mood states are intimately tied to bulimic behaviors and may in fact precipitate such behavior.     

Safety behaviours preserve threat beliefs: Protection from extinction of human fear conditioning by an avoidance response

A laboratory autonomic conditioning procedure was used to establish fear conditioning in human participants by pairing neutral stimuli with electric shock. Participants were also trained to make a button-press response to avoid shock. A target fear stimulus was then extinguished by presenting it without shock. The experimental group was given the opportunity to make the avoidance response during extinction whereas the control group was not. When the fear stimulus was tested without the response available, the control group showed normal extinction of both shock expectancy ratings and skin conductance responses, but the experimental group showed “protection from extinction”: they continued to give high expectancy ratings and strong skin conductance responses. We interpret this effect as analogous to the role of within-situation safety behaviours in preserving threat beliefs during exposure therapy for anxiety disorders. The results support a cognitive account of learning and anxiety. The procedure provides a potential laboratory model for further examination of the cognitive and neural mechanisms underlying anxiety and its reduction.     

EFFECTS OF POINT‐LOSS PUNISHERS ON HUMAN SIGNAL‐DETECTION PERFORMANCE

Three experiments using human participants varied the distribution of point‐gain reinforcers or point‐loss punishers in two‐alternative signal‐detection procedures. Experiment 1 varied the distribution of point‐gain reinforcers for correct responses (Group A) and point‐loss punishers for errors (Group B) across conditions. Response bias varied systematically as a function of the relative reinforcer or punisher frequencies. Experiment 2 arranged two conditions — one where an unequal ratio of reinforcement (5:1 or 1:5) was presented without punishment (R‐only), and another where the same reinforcer ratio was presented with an equal distribution of point‐loss punishers (R+P). Response bias was significantly greater in the R‐only condition than the R+P condition, supporting a subtractive model of punishment. Experiment 3 varied the distribution of point‐gain reinforcers for correct responses across four unequal reinforcer ratios (5:1, 2:1, 1:2, 1:5) both without (R‐only) and with (R+P) an equal distribution of point‐loss punishers for errors. Response bias varied systematically with changes in relative reinforcer frequency for both R‐only and R+P conditions, with 5 out of 8 participants showing increases in sensitivity estimates from R‐only to R+P conditions. Overall, the results indicated that punishers have similar but opposite effects to reinforcers in detection procedures and that combined reinforcer and punisher effects might be better modeled by a subtractive punishment model than an additive punishment model, consistent with research using concurrent‐schedule choice procedures.     

Maternal correlates of 2‐year‐old American Indian children's social‐emotional development in a Northern Plains tribe

The developmental experiences of very young American Indian children today are not well documented in the current literature. The present study sought to explore the social‐emotional development of American Indian toddlers living on a Northern Plains reservation, as a function of maternal variables. Mothers completed self‐report questionnaires about their experiences and their children's development. Observer ratings of children's development also were conducted. Maternal stress, substance use/abuse, perceptions of stress in the mother–child relationship, social support, and American Indian cultural identity were significantly related to children's social‐emotional development. This study is the first to explore these relationships in a Northern Plains American Indian sample of young children and their mothers. Results suggest possible points of intervention for improving the developmental outcomes of very young American Indian children.     

Automated gait analysis in the open-field test for laboratory mice

In this article, an automated and accurate mouse observation method, based on a conventional test for motor function evaluation, is outlined. The proposed measurement technique was integrated in a regular open-field test, where the trajectory and locomotion of a free-moving mouse were measured simultaneously. The system setup consisted of a transparent cage and a camera placed below it with its lens pointing upward, allowing for images to be captured from underneath the cage while the mouse was walking on the transparent cage floor. Thus, additional information was obtained about the position of the limbs of the mice for gait reconstruction. In a first step, the camera was calibrated as soon as it was fixed in place. A linear calibration factor, relating distances in image coordinates to real-world dimensions, was determined. In a second step, the mouse was located and its body contour segmented from the image by subtracting a previously taken “background” image of the empty cage from the camera image. In a third step, the movement of the mouse was analyzed and its speed estimated from its location in the past few images. If the speed was above a 1-sec threshold, the mouse was recognized to be running, and the image was further processed for footprint recognition. In a fourth step, color filtering was applied within the recovered mouse region to measure the position of the mouse’s paws, which were visible in the image as small pink spots. Paws that were detected at the same location in a number of subsequent images were kept as footprints—that is, paws in contact with the cage floor. The footprints were classified by their position relative to the mouse’s outline as corresponding to the front left or right paw or the hind left or right paw. Finally, eight parameters were calculated from the footprint pattern to describe the locomotion of the mouse: right/left overlap, front/hind base, right/left front limb stride, and right/left hind limb stride. As an application, the system was tested using normal mice and mice displaying pentobarbital-induced ataxia. The footprint parameters measured using the proposed system showed differences of 10% to 20% between normal and ataxic mice.     

Determining risk in pediatric research with no prospect of direct benefit: time for a national consensus on the interpretation of federal regulations

United States federal regulations for pediatric research with no prospect of direct benefit restrict institutional review board (IRB) approval to procedures presenting: 1) no more than "minimal risk" ( section sign 45CFR46.404); or 2) no more than a "minor increase over minimal risk" if the research is commensurate with the subjects' previous or expected experiences and intended to gain vitally important information about the child's disorder or condition ( section sign 45CFR46.406) (DHHS 2001). During the 25 years since their adoption, these regulations have helped IRBs balance subject protections with the pursuit of scientific knowledge to advance children's welfare. At the same time, inconsistency in IRB application of these regulations to pediatric protocols has been widespread, in part because of the ambiguity of the regulatory language. During the past decade, three federally-charged committees have addressed these ambiguities: 1) the National Human Research Protections Advisory Committee (NHRPAC) (Washington, DC), 2) the Institute of Medicine (IOM) Committee on the Ethical Conduct of Clinical Research Involving Children (Washington, DC); and 3) the United States Department of Health and Human Services Secretary's Advisory Committee for Human Research Protections (SACHRP) (Washington, DC). The committees have reached similar conclusions on interpretation of language within regulations section sign section sign 45CFR46.404 and 406; these conclusions are remarkably consistent with recent international recommendations and those of the original National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research (1977) report from which current regulations are based. Drawing on the committees' public reports, this article identifies the ethical issues posed by ambiguities in regulatory language, summarizes the committees' deliberations, and calls for a national consensus on recommended criteria.     

Anxiety sensitivity and retaliatory aggressive behavior in research volunteers

An important focus of recent aggression research has been to identify personality variables that influence the expression of aggression. One such variable may be anxiety sensitivity (AS). Individuals high in AS fear unpleasant anxiety-related physiological sensations and perhaps physiological arousal in general. Accordingly, people high in AS are motivated to avoid situations that produce these sensations. With respect to aggressive encounters, an intense attack by an opponent involves significant physiological arousal. High anxiety-sensitive individuals may therefore attempt to decrease the intensity of the interaction by responding in a non-aggressive or conciliatory manner. To test this possibility, 112 community volunteers completed a measure of AS and a well-validated laboratory task designed to assess aggressive behavior. As predicted, an inverse relation between AS and extreme aggressive responding was found. Specifically, as AS increases, retaliatory aggression is less likely after intense attack by an opponent.