Hormonal responses accompanying fear and agitation in the squirrel monkey

The adrenocortical and gonadal responses of 14 male monkeys were evaluated during four experimental conditions in order to evaluate the influence of social interactions on endocrine responsiveness. Plasma hormone levels were determined during the establishment of social relations, after 60-min exposures to a novel environment, after 60-min exposures to a snake, and 60 min after ACTH administration. Both adrenal and gonadal secretion changed significantly during the first day after social relations were established, although only dominant males showed increases in testosterone, whereas cortisol levels rose in all subjects. Increases in cortisol, but not testosterone, were also observed following exposure to novelty or a snake. The presence of a social partner reduced signs of behavioral disturbance during these test conditions, although the adrenal responses were equivalent or greater than when tested alone. This finding qualifies earlier research which indicated that social support was beneficial for reducing stress when squirrel monkeys were tested in larger groups in their home environment.     

Dominance behavior in the rat following lesions of the caudate nuclei.

Rats with bilateral lesions of the anterior caudate nucleus or the dorsolateral frontal cortex were tested against sham-operated rats in a straight-alley dominance situation. In 91% of encounters the caudate lesion rats forced the sham-operated animals to retreat. The frontal lesion rats won only 56% of their encounters, a proportion no different to that expected by chance. The performance of the caudate-damaged rats could not be explained satisfactorily in terms of increased motivation, changes in activity, motor impairments, or perseverative tendencies. It seemed more likely that the apparent increase in dominance was associated with changes in the level of aggression.     

Social behavior of juvenile rhesus monkeys after amygdalectomy in infancy

Six $\text{3}\text{1}\text{2}$-yr-old rhesus monkeys that had sustained a bilateral amygdalectomy in infancy were paired with 6 intact age-mates, and behaviors were observed immediately and after a 24-hr interval. Amygdaloid animals were submissive to controls, and were hyperactive during all tests, changing rapidly from one behavior to another. Earlier studies with these infant-operated monkeys showed that an abnormal fear of intact age-mates first appeared during the second 6 mo of life. The amygdaloid animals had been hyperactive when by themselves as early as 6 mo of age, but there was no evidence of hyperactivity in social situations during earlier tests. The present paper presents the histology for these infant-operated monkeys, and suggests that behavioral deficits resulting from amygdalectomy in infancy increase in severity with advancing maturation. The aberrations observed by $\text{3}\text{1}\text{2}$ yr are similar to those observed after amygdalectomy in mature animals.     

Dominance,plasma testosterone levels,and testis size in house mice artificially selected for high activity levels

Male house mice (Mus domesticus) from four replicate lines selectively bred for high voluntary wheel-running behavior were compared with four random-bred control lines with respect to dominance, testis size, and plasma testosterone level. Behavior was measured with a tube apparatus in which focal mice encountered a standard opponent from an inbred strain, and positions of mice were scored over a 10-min period; the test was replicated the following day. Blood samples were taken from undisturbed mice 1 week prior to testing (baseline condition) and immediately after the first tube test; plasma testosterone was measured by enzyme immunoassay with chromatography. As compared with control lines, mice from selected lines tended to be smaller in body mass, to have larger testes, and were significantly less likely to advance towards their opponent during the second tube-test encounter. However, no significant differences in either baseline or post-encounter testosterone levels were detected. Significant differences in body mass, relative testis size, position during the first tube-test encounter, and baseline testosterone were found among the replicate lines within linetype, which indicates founder effects, random genetic drift, unique mutations, and/or multiple responses to selection. At the level of individual variation (residuals from nested analysis of covariance models), an inverse relationship between baseline testosterone and advancing in the tube test was observed, and the relationship was stronger during the second test day. This unexpected result may reflect an alternate coping strategy.     

Dynamic body weight and body composition changes in response to subordination stress

Social stress is prevalent in many facets of modern society. Epidemiological data suggest that stress is linked to the development of overweight, obesity and metabolic disease. Although there are strong associations between the incidence of obesity with stress and elevated levels of hormones such as cortisol, there are limited animal models to allow investigation of the etiology of increased adiposity resulting from exposure to stress. Perhaps more importantly, an animal model that mirrors the consequences of stress in humans will provide a vehicle to develop rational clinical therapy to treat or prevent adverse outcomes from exposure to chronic social stress. In the visible burrow system (VBS) model of chronic social stress mixed gender colonies are housed for 2 week periods during which male rats of the colony quickly develop a dominance hierarchy. We found that social stress has significant effects on body weight and body composition such that subordinate rats progressively develop characteristics of obesity that occurs, in part, through neuroendocrine alterations and changes in food intake amount. Although subordinate rats are hyperphagic following social stress they do not increase their intake of sucrose solution as control and dominants do suggesting that they are anhedonic. Consumption of a high fat diet does not appear to affect development of a social hierarchy and appears to enhance the effect that chronic stress has on body composition. The visible burrow system (VBS) model of social stress may be a potential laboratory model for studying stress-associated metabolic disease, including the metabolic syndrome.     

Using a partner׳s facial emotion to elucidate social dominance motivation induced by an SSRI

Previous studies independently showed that acute treatment with a selective serotonin reuptake inhibitor (SSRI) enhanced happy face recognition, and dominance behaviors which might reflect enhancement of reward sensitivity. The present study aimed to determine whether such a mechanism would be related to social resource acquisition induced by an SSRI. Forty healthy subjects were recruited for the experiment. A randomized, double-blind, placebo-controlled crossover nested within confederate type (happy, fearful, or sad) trial of a single-dose of 10 mg escitalopram versus placebo was conducted with a two-week washout period. In each of the treatment groups, the subjects interacted socially with one of the three types of confederate in a waiting room for 3-minute. Then, they went to an individual laboratory and were led to believe that they played the Mixed-motive game with the confederate. The game measures punitive/cooperative behaviors by how participants allocate higher/lower game scores to the confederate and communicate cooperation/ingratiation/helplessness/sadness/blaming/extrapunitive, messages to the confederate. Significant treatment-by-confederate type interactions were observed through game score distributions and ingratiation messages to the confederate and attentive eye gaze. In the happy confederate condition, escitalopram increased ingratiation messages and lowered points awarded to the confederate. In the fearful confederate condition, escitalopram increased ingratiation messages and reduced time spent looking away from the confederate. No changes in these measures were found in the sad confederate condition. Therefore acute escitalopram treatment enhances reward sensitivity to the facial emotions of social partners which in turn increases social resource acquisition and social dominance towards happy but not fearful social partners.     

Postweaning social experience and adult aggression in rats

One group of male rats was reared continuously in small, stable colonies of three animals each during a ten-week period beginning when they were 46 days old. A second group of animals was also reared in small groups of three animals each but membership within these colonies was randomly changed at weekly intervals. Thereafter, all subjects were housed in individual cages. A 24 hr test of the subjects' aggression toward an unfamiliar male conspecific at 130-133 days of age indicated that only the heaviest animal in each of the stable colonies was aggressive. In contrast, all animals in the random-composition group were aggressive toward intruders. Scores on a second test of intruder-directed aggression administered when the subjects were nine months old were significantly related to scores on the first aggression test. Subtle variations in social experience during development are critical in establishing long-term patterns of aggression toward conspecifics in laboratory rats.     

Perceived dominance in physicians: Are female physicians under scrutiny?

Objective

This research aims at identifying how specific physician verbal and nonverbal behaviors are related to perceived dominance of female and male physicians.

Method

Analogue patients (163 students) watched videotaped excerpts of eight physicians and indicated how dominant they perceived each physician to be.

Results

Female physicians who spoke more, talked more while doing something else, spoke with louder voices, modulated their voices more, were oriented more toward the patients, sat at a smaller interpersonal distance, were more expansive, and had a more open arm position were perceived as more dominant. These relations were significantly more pronounced in female than in male physicians. With respect to verbal behavior, not agreeing with the patient, structuring the discussion, setting the agenda, and asking questions were related to being perceived as significantly more dominant in female than in male physicians.

Conclusion

Patients interpret verbal and nonverbal female and male physicians’ cues differently. If a behavior contradicts gender stereotypes regarding women, this behavior is perceived as particularly dominant in female physicians.

Practice implications

To provide optimal care, physicians need to be aware of the expectations their patients harbor toward them—especially expected behavior related to the gender of the physician.