Socio-Ecological Disruptions at Critical Periods During Development Alter Stress Responses and Hippocampal Dendritic Morphology of Prairie Voles: Implications for Social Monogamy

Emotions are often associated with the evolution of monogamy. For example, fear of cuckoldry has been recently proposed as the driving force for human monogamy. We used prairie voles (Microtus ochrogaster) as a model of human behavior to study how stress reactivity is shaped by socio-ecological disruptions experienced as neonates and as subadults. We hypothesized that social disruptions would have a greater impact on the vole's stress levels than ecological disruptions, and that females would be more susceptible to the experience than males. At 6 days postpartum, the housing conditions were manipulated to have offspring raised by: (1) both parents under a protective cover (NoDisrupt); (2) Both parents uncovered (EcoDisrupt); (3) Mother alone covered (SocDisrupt); (4) Mother alone uncovered (SocEcoDisrupt). To experience disruptions as subadults, offspring were weaned then housed either alone (Isolate) or with a same-sex sibling (Social). As adults, each offspring was placed in an open-field arena and tested over 3 consecutive days to measure its behavior in response to an empty space (Day1), a same-sex vole in a container (Day2), and an empty container (Day3). The brain of a subgroup of subjects was processed for Golgi staining to assess the impact of disruptions on hippocampal dendritic morphology in adulthood. Males that experienced social disruption in early life displayed lower stress levels on Day2 of testing than males and females in other groups. This effect was only evident in males that did not experience social disruptions as subadults. Socio-ecological disruptions at postpartum had an unanticipated impact on the hippocampus of the voles. The apical dendrites of the CA3 neurons in male and female voles that experienced either social or ecological disruptions in early life and remained socially isolated as subadults were longer than those in undisturbed voles. Our results suggest that social disruptions experienced in early life modulate the male's stress-related behaviors and may thus influence his monogamous tendencies. Exposure to disruptions may also impact the memory circuits of the brain that monogamous animals use to make mating decisions

Changes in vasopressin pathways in extrahypothalamic brain regions of male prairie voles (Microtus ochrogaster) during the reproductive period

To see if the vasopressinergic system, implicated in maternal behavior, changes during parenthood in different directions in males and females, I examined the pattern of vasopressin immunoreactivity in prairie voles in which both mother and father care for young and meadow voles in which only the mother cares for young. For both species, I compared the densities of vasopressin immunoreactive (AVP-ir) fibers in males and females that were either sexually naive or in parental state. In both species, AVP-ir fiber densities in the lateral septum (LS), and the lateral habenular nucleus (LHN) were higher in males than in females regardless of their parental state. AVP-ir fiber density in the LS and the LHN was reduced in parental prairie-vole males, while no differences were found in females. The AVP-ir in the LS of parental meadow-vole males and females did not show changes, while the fiber density in their LHN was increased. To see if AVP immunoreactivity in male prairie voles changes before or after the birth of pups, I compared AVP-ir fiber density among males and females that were either housed separately or housed together until after mating (3-P), during early gestation (13-P) or late gestation (21-P), or after the birth of pups (26-P). Under all these conditions, AVP-ir fibers in the LS and the LHN were much denser in males than in females. In males, the lowest density of AVP-ir in the LS and the LHN was found in 3-P males. An intermediate density was found in 13-P and 26-P males. An equally high density was found in sexually naive (0-M) and in 21-P males. In females, no changes in AVP immunoreactivity were found. The decrease in AVP-ir fibers of 3-P males occurred only in presence of a female. Changes in AVP immunoreactivity of male prairie voles could be related either to sexual activity which takes place after the first 3 days of cohabitation and again around pups\u27 birth, behavioral changes associated with pair bonding, or induction of paternal behavior

B.: A framework for the analysis of attacks against social tagging systems. In

Social tagging systems provide an open platform for users to share and annotate their resources such as photos and URLs. Due to their open nature, however, these systems present a security problem. Malicious users may try to distort the system’s behavior by inserting erroneous or misleading annotations, thus altering the way in which information is presented to legitimate users. This paper addresses the problem of modeling attacks against social tagging systems and evaluating their impact on the systems ’ behavior. Gaining a fundamental understanding of the nature and impact of such attacks will hopefully lead to more secure and robust social Web applications. We present the dimensions that characterize an attack and outline a framework to model the attacks based on various navigation channels and target elements. Using our framework we classify and identify different types of potential attack strategies against a social tagging system. We implement two of our attack models and evaluate their impact on retrieval algorithms commonly used by tagging systems

Mechanisms and Time Course for Induction of Paternal Behavior in Prairie Voles (Microtus Ochrogaster)

Prairie voles are a monogamous species and males show paternal behavior. After mating, paternal responsiveness increases gradually during the gestation period, peaking before young are born. We examined the importance of cohabitation with a female and the time course for a gradual intensification of paternal care. Males housed with their brothers since weaning were separated. Each male was housed alone, with a strange female, or with a brother. A male housed with a female remained with her either until mating occurred or throughout gestation. Males in each group were tested for paternal behavior 3 times, in early, mid and late gestation periods. Males that were housed alone attacked the young more than those housed with another vole. A male exposed to a female, whether he had mated or not, engaged in more parenting than a male exposed to a brother. A male that remained with his mate during the gestation period was more parental than an isolated male that was housed alone. Contact with another vole reduces infanticidal tendencies; brief physical contact with a female, with or without mating, intensifies paternal responsiveness; and further cohabitation is not essential. [ABSTRACT FROM AUTHOR

Changes in Paternal Responsiveness of Prairie Voles ( Microtus ochrogaster) in Response to Olfactory Cues and Continuous Physical Contact with a Female

In mammals, paternal care is rarely displayed, and we know little about the mechanisms regulating this behavior. Prairie voles ( Microtus ochrogaster) are ideal mammals for the study of paternal behavior because they are a monogamous, bi-parental species that is easily raised in the laboratory. Paternal responsiveness occurs at moderate levels in sexually-naive voles and is heightened following a short cohabitation period of 72 h with a female. To determine how increased levels of paternal care are maintained after the initial cohabitation period, we tested the paternal behavior of males that were housed in isolation, were in physical contact with a female, or were exposed to various olfactory cues. The results indicate that the absence of odor cues from a female did not diminish the male’s motivation to care for infants following the initial cohabitation period. In contrast, odor cues from a male appeared to negatively influence the male’s paternal tendencies. The data also show that males that had continuous physical contact with a female spent more time responding paternally and more time hovering over the young compared to males that were housed alone. Together, these results suggest that although paternal behavior is maximized in response to continuous physical contact with females, olfactory cues may not be necessary for the maintenance of heightened paternal behavior