Predator-Induced Plasticity in Spotted Salamanders (Ambystoma maculatum)

The ability to respond plastically to the environment has allowed amphibians to evolve adaptive responses to spatial and temporal variation in predation threat. However, animals exposed to predators may also show costs of plasticity or tradeoffs. This study examines predator-induced plasticity in larval development, behavior, and metamorphosis in the spotted salamander, Ambystoma maculatum. Salamanders were raised in two treatments: with predator cues (a fish predator, genus Lepomis, on the other side of a divided tank), or without predator cues. During the larval stage the predator treatment group experienced higher mortality rates than the no-predator treatment group. Behavioral trials revealed that predator treatment animals ate less than those not exposed, and that this feeding response was immediately inducible and had lasting effects. Animals in the predator treatment group had smaller tail areas during the mid-larval period. Feeding and body size effects may have contributed to increased mortality in the predator-treatment animals. The timing of metamorphic onset was not affected by the presence of predators, but predator-treatment salamanders had shorter snout/vent lengths at metamorphosis. The duration of metamorphosis showed a potentially adaptive plastic response to the presence of predator cues: metamorphosis was longest in the no-predator treatment group, reduced in the predator treatment group, and even further reduced for animals exposed to predator cues only during metamorphosis. Overall, we found a mix of potentially adaptive and costly plastic responses in spotted salamanders.

Behavioral Implications of Knockout for the Dyslexia-Risk Gene Dcdc2 in Mice

Several genetic linkage and epidemiological studies have provided strong evidence that DCDC2 is a candidate gene for developmental dyslexia, a disorder that impairs a person’s reading ability despite adequate intelligence, education, and socio-economic status. Studies investigating embryonic intra-ventricular RNA interference (RNAi) of Dcdc2, a rat homolog of the DCDC2 gene in humans, indicate disruptions in neuronal migration in the rat cortex during development. Interestingly, these anatomical anomalies are consistent with post mortem histological analysis of human dyslexic patients. Other rodent models of cortical developmental disruption have shown impairment in rapid auditory processing and learning maze tasks in affected subjects. The current study investigates the rapid auditory processing abilities of mice heterozygous for Dcdc2 (one functioning Dcdc2 allele) and mice with a homozygous knockout of Dcdc2 (no functioning Dcdc2 allele). It is important to note that this genetic model for behavioral assessment is still in the pilot stage. However, preliminary results suggest that mice with a genetic mutation of Dcdc2 have impaired rapid auditory processing, as well as non-spatial maze learning and memory ability, as compared to wildtypes. By genetically knocking out Dcdc2 in mice, behavioral features associated with Dcdc2 can be characterized, along with other neurological abnormalities that may arise due to the loss of the functioning gene.

Gender Difference in Emotional and Behavioral Responses of Being Rendered Invisible

This study examined gender differences in emotional and behavioral responses to an experience of being invisible to others. Invisibility was defined as being ignored, slighted and overlooked by others. Participants recalled their own experience and answered questions about it and their responses on an anonymous web-based survey. Although such experiences could be very unpleasant, people may respond to such negative experiences very differently. It was hypothesized that in a patriarchal society like the United States in which men hold more power than women, that men would show emotion that was more aggressive such as anger, and respond more violently to incidents they were not respected. Women, on the other hand, were expected to be more subservient in their behavior and responses, show submissive emotions such as sadness, and respond less violently when they were not respected.

The Associations Between Social, Behavioral, and Health Risk Factors on a High School Student’s Decision to Pursue Post High School Plans

Background: Due to the relationship between SES and health, pursuing post high-school plans can lead to better future health outcomes for the student. The current paper assesses how behavioral and health risk factors, and family and social support, effect a student’s decision to pursue post high school plans. Methods: Data from the Youth Behavioral Component of the 2007 Connecticut School Health Survey were analyzed. Composite measures of exposure to/participation in violent behavior, mental and physical health, family/social support and substance abuse were created. The effects of these domains on the decision to pursue post high-school plans were assessed using logistic regression. Data were stratified by socioeconomic status. Results: Low SES students were more likely than high SES students to be doubtful for post high-school plans. Cocaine abuse emerged as the risk factor that put low SES students at the highest odds of not pursuing post high-school plans, followed by involvement in violent/aggressive behavior, and receiving less family/social support than their peers. Similar findings regarding violence and family/social support were found in the high SES group. Findings regarding substance abuse in the high SES group were not statistically significant. Discussion: Prevention programs regarding violence and substance abuse may have the added benefit of increasing the likelihood that high school students will make post high school plans. Preventing cocaine use among low SES students may be of particular importance. Violence prevention measures should be tailored to the target group. Adequate family/social support emerged as an encouraging factor for post high school plans.

Behavioral Profile of the Novel Cannabinoid Agonist AM4054

Although cannabinoid drugs have been used for thousands of years both recreationally and therapeutically, little has been known about their mechanisms of action until recently. Since the discovery of the endogenous cannabinoid CB1 receptor in 1988, the behavioral profile of cannabinoid receptor ligands has been much more thoroughly defined. Cannabinoid CB1 agonists have been shown to produce a variety of behavioral effects including suppression of locomotion, catalepsy, hypothermia, and analgesia. Research has also demonstrated that these behavioral effects can be inhibited by CB1 receptor antagonists including SR 141716 and AM 251. Although behavioral indicators of anxiety including thigmotaxis have been observed in several different paradigms, there is inconclusive and often times contradictory evidence to define the role of anxiety in CB1 receptor activation. The present study addressed the behavioral profile of AM 4054, a novel full agonist at the CB1 receptor, as well as the ability of the CB1 antagonist AM 251 to reverse these effects. To further identify and expand research on the suppression of locomotion and induction of thigmotaxis with the administration of a CB1 agonist, experiment 1 was conducted in the open field. In this experiment, each rat (n=40) was randomly assigned one of the five treatments: vehicle, 0.16, 0.32, 0.64, or 1.25 mg/kg AM 4054. After a 30 minute pre-treatment, each subject was tested in the open field for 18 minutes. Results indicated that AM 4054 produced a dose-related suppression of locomotion as well as the subtle presence of thigmotaxis in two out of four doses. In experiment 2, subjects (n=40) received either vehicle or 2.0 or 4.0 mg/kg AM 251 60 minutes prior to testing. After 30 minutes, the subjects were given either a 0.3 mg/kg dose of AM 4054 or vehicle. After a total pretreatment duration of 60 minutes, the animals were tested on a battery of tasks including an 18 minute session in locomotor boxes. Experiment 2 was a continuation of a previous study conducted in the same lab, which confirmed the effects of AM 4054 on this tetrad of tasks as being consistent with other cannabinoid agonists. In this experiment the effects of AM 4054 were reversed by the administration of the CB1 antagonist AM 251. Past studies have shown that AM 4054 is a highly potent drug with behavioral actions similar to other cannabinoid CB1 agonists. Furthermore, AM 4054 can be a useful drug in future studies, and has potential therapeutic value for the treatment of various conditions.

RELATIONS AMONG REMEMBERED PARENTAL ACCEPTANCE AND BEHAVIORAL CONTROL IN CHILDHOOD, ADULTS' CURRENT PSYCHOLOGICAL ADJUSTMENT, AND CAREER INDECISIVENESS

This study tested the hypothesis that career indecisiveness among men tends to be associated with different levels of self-reported psychological adjustment and with different remembrances of parental (maternal and paternal) acceptance and behavioral control in childhood from those of women. One hundred twenty-six respondents ages 17 through 54 (M = 23.7 years, SD = 8.21 years) participated in this study. Thirty-seven where males; 90 were females. Measures used in this study included the Career Decision Scale, the Adult version of the Parental Acceptance-Rejection/Control Questionnaire for mothers and for fathers, and the Adult version of the Personality Assessment Questionnaire. Both men and women remembered their mothers as well as their fathers as being loving in childhood. Additionally, men and women remembered both parents as being moderately behaviorally controlling in childhood. Finally, both men and women reported a fair level of psychological maladjustment. And on average, both men and women were fairly indecisive about their careers. Results of analyses supported the hypothesis in that career indecisiveness among women but not men was significantly correlated with remembered maternal and paternal acceptance in childhood, as well as with self-reported psychological adjustment and age. However, only women’s self-reported psychological adjustment made a significant and unique contribution to variations in their reports of career indecisiveness. None of the predictor variables were significantly associated with career indecisiveness among men.

Ontogenetic Effects of Hatching Plasticity in the Spotted Salamander (Ambystoma maculatum) due to Egg and Larval Predators

The ability to respond plastically to the environment has allowed amphibians to evolve a response to spatial and temporal variation in predation threat (Benard 2004). Embroys exposed to egg predation are expected to hatch out earlier than their conspecifics. Larval predation can induce a suite of phenotypic changes including growing a larger tail area. When presented with cues from both egg and larval predators, embryos are expected to respond to the egg predator by hatching out earlier because the egg predator presents an immediate threat. However, hatching early may be costly in the larval environment in terms of development, morphology, and/or behavior. We created a laboratory experiment in which we exposed clutches of spotted salamander (Ambystoma maculatum) eggs to both egg (caddisfly larvae) and larval (A. opacum) predators to test this hypothesis. We recorded hatching time and stage and took developmental and morphological data of the animals a week after hatching. Larvae were entered into lethal predation trials with a larval predatory sunfish (Lepomis sp.) in order to study behavior. We found that animals exposed to the egg predator cues hatched out earlier and at earlier developmental stages than conspecifics regardless of whether there was a larval predator present. Animals exposed to larval predator cues grew relatively larger tails and survived longer in the lethal predation trials. However the group exposed to both predators showed a cost of early hatching in terms of lower tail area and shorter survival time in predation trials. The morphological and developmental effects measured of hatching plasticity were transient as there were no developmental or morphological differences between the treatment groups at metamorphosis. Hatching plasticity may be transient but it is important to the development and survival of many amphibians.