Effect of different parameters of shock on tonic immobility

Four separate experiments were conducted with chickens to explore the effects of various parameters of electric shock on tonic immobility. Immobilizing subjects at varying times after the receipt of shock affected the duration of immobility only after delays of over 15 min. Duration of shock affected immobility differently, depending upon whether alternating current or continuous direct current was used. The effects of continuous dc, pulsating dc. and ac shock were also examined. The results were discussed in terms of shock onset-offset characteristics being an important consideration.     

The tonic immobility reaction in chickens: Response characteristics and methodology

A total of 379 chickens were run in five studies to assess the effect of different procedures on tonic immobility and to measure some of the response components of the reaction. The optimal period of manual restraint, by way of producing the most durable immobility response, was found to be 15 sec, and pretest holding conditions were shown to exert a significant influence on the reaction in naive birds. Birds who defecated during immobility or shortly after termination, remained immobile longer than comparable nondefecators. Duration of eye closure and latency of vocalization were also found to be good predictors of the duration of an immobility episode.     

Episodic-like memory in zebrafish

Episodic-like memory tests often aid in determining an animal’s ability to recall the what, where, and which (context) of an event. To date, this type of memory has been demonstrated in humans, wild chacma baboons, corvids (Scrub jays), humming birds, mice, rats, Yucatan minipigs, and cuttlefish. The potential for this type of memory in zebrafish remains unexplored even though they are quickly becoming an essential model organism for the study of a variety of human cognitive and mental disorders. Here we explore the episodic-like capabilities of zebrafish (Danio rerio) in a previously established mammalian memory paradigm. We demonstrate that when zebrafish were presented with a familiar object in a familiar context but a novel location within that context, they spend more time in the novel quadrant. Thus, zebrafish display episodic-like memory as they remember what object they saw, where they saw it (quadrant location), and on which occasion (yellow or blue walls) it was presented.     

Cognitive deficits, schizophrenia, and the anterior cingulate cortex

Cognitive deficits are thought to be responsible for some of the symptoms and dysfunction in schizophrenia. Recent research on the anterior cingulate cortex supports this assumption. More detailed and definitive evidence for this association will require identification of specific neural networks whose abnormal structure, connections or activity create the cognitive deficits in question.     

Auditory disturbances promote temporal clustering of yawning and stretching in small groups of budgerigars (Melopsittacus undulatus)

Yawning may serve both social and nonsocial functions. When budgerigars (Melopsittacus undulatus) are briefly held, simulating capture by a predator, the temporal pattern of yawning changes. When this species is observed in a naturalistic setting (undisturbed flock), yawning and also stretching, a related behavior, are mildly contagious. On the basis of these findings, we hypothesized that a stressful event would be followed by the clustering of these behaviors in a group of birds, which may be facilitated both by a standard pattern of responding to a startling stressor and also contagion. In this study, we measured yawning and stretching in 4-bird groups following a nonspecific stressor (loud white noise) for a period of 1 hr, determining whether auditory disturbances alter the timing and frequency of these behaviors. Our results show that stretching, and to a lesser degree yawning, were nonrandomly clumped in time following the auditory disturbances, indicating that the temporal clustering is sensitive to, and enhanced by, environmental stressors while in small groups. No decrease in yawning such as found after handling stress was observed immediately after the loud noise but a similar increase in yawning 20 min after was observed. Future research is required to tease apart the roles of behavioral contagion and a time-setting effect following a startle in this species. This research is of interest because of the potential role that temporal clumping of yawning and stretching could play in both the collective detection of, and response to, local disturbances or predation threats.     

Handgrip strength and socially dominant behavior in male adolescents

Handgrip strength (HGS) is highly heritable and a good overall measure of strength and muscle function. Indicative of blood testosterone levels and fat-free body mass, HGS is also highly sexually dimorphic. Recent psychological research shows that HGS is correlated with a number of social variables, but only in males. We conducted three studies to further investigate the relationship between HGS and measures of aggression and social competition among adolescents. Consistent with previous reports, correlations were almost exclusive to males, but this was only visible during late adolescence (i.e., high school). These findings support evolutionary hypotheses regarding grip strength in male-male competition and suggest that similar to measures of testosterone, HGS is a measure that is predictive of social behavior in older adolescent males.     

Peer victimization in adolescence has different effects on the sexual behavior of male and female college students

We studied levels of peer victimization from an evolutionary perspective by investigating self-reported victimization during adolescence in relation to sexual behavior in college students. One-hundred and twelve (47 female) undergraduates completed self-report measures of victimization during middle and high school, onset of sexual activity, and number of sexual partners. Nearly 85% of victimization during adolescence was perpetrated by members of the same sex. Furthermore, results show that this intrasexual victimization (particularly indirect forms) was negatively correlated with reproductive opportunities in males, but positively correlated in females. Males who were frequently victimized had fewer total sexual partners and partners per year on average, while females who were often victims of aggression reported having more sexual partners and an earlier onset of sexual activity. Regression analysis revealed that demeaning, diminishing and embarrassing was the most significant predictor of the rate of sexual activity in both sexes (although this relationship was inverted between them), while teasing was the best predictor of total sexual partners in females. This evidence is consistent with evolutionary interpretations regarding human aggression and competition, as well as with recent findings suggesting that indirect victimization during adolescence is a form of intrasexual competition associated with reproductive opportunities.