Martin Kavaliers

Social and sexual incentive properties of estrogen receptor α, estrogen receptor β, or oxytocin knockout mice

Social and sexual incentive motivation, defined as the intensity of approach to a social and a sexual incentive, respectively, were studied in female Swiss Webster mice. In the first experiment, the social incentive was a castrated mouse of the same strain as the females, whereas the sexual incentive was an intact male mouse of the same strain. Ovariectomized females were first tested after oil treatment and then after administration of estradiol benzoate + progesterone in doses sufficient to induce full receptivity. The hormones increased sexual incentive motivation while leaving social incentive motivation unaffected. This suggests that sexual incentive motivation in the female mouse is dependent on ovarian hormones. In the next experiment, ovariectomized females were tested with an intact, male estrogen receptor α knockout and its wild type as incentives, first without hormones and then when fully receptive. There were no differences in incentive properties between the wild type and the knockout. In a similar experiment, we used an intact male estrogen receptor β knockout and its corresponding wild type as incentives. The wild type turned out to be a more attractive social incentive than the knockout, while they were equivalent as sexual incentives. Finally, an intact male oxytocin knockout and its wild type were used as incentives. The knockout turned out to be a superior incentive, particularly a superior sexual incentive. The fact that the estrogen receptor β and oxytocin knockouts have incentive properties different from their wild types may be important to consider in studies of these knockouts’ sociosexual behaviors.

NMDA-mediated social learning of fear-induced conditioned analgesia to biting flies.

Although fear conditioning has received extensive neurobiological attention little is known about social learning whereby one individual may learn and acquire the fear responses of another. A 30 min exposure to intact biting flies (stable fly, Stomoxys calcitrans L.) elicits in individual fly-naive mice analgesia and active self burying responses to avoid the flies. Fly-naive observer mice that witnessed other demonstrator mice being attacked by biting flies exhibited analgesia and self-burying to avoid flies when exposed 24 h later to altered flies whose biting mouth parts were removed. The opiate antagonist naloxone, while reducing the analgesic responses elicited by exposure to a fly-stressed demonstrator, did not affect either the subsequent conditioned analgesia or self-burying. However, the specific NMDA receptor antagonist NPC 12626, given to observers prior to, but not after, presentation of fly attacked demonstrators blocked the socially determined conditioned analgesia and self burying avoidance. This supports NMDA involvement in the mediation of the social transmission and long-term (24 h) retention of conditioned analgesia and fear.

Mechanisms underlying sexual and affiliative behaviors of mice: relation to generalized CNS arousal

The field of social neuroscience has grown dramatically in recent years and certain social responses have become amenable to mechanistic investigations. Toward that end, there has been remarkable progress in determining mechanisms for a simple sexual behavior, lordosis behavior. This work has proven that specific hormone-dependent biochemical reactions in specific parts of the mammalian brain regulate a biologically important behavior. On one hand, this sex behavior depends on underlying mechanisms of CNS arousal. On the other hand, it serves as a prototypical social behavior. The same sex hormones and the genes that encode their receptors as are involved in lordosis, also affect social recognition. Here we review evidence for a micronet of genes promoting social recognition in mice and discuss their biological roles.

Oxytocin, Vasopressin and Related Peptides in the Regulation of Behavior: Plate section

The mammalian neurohypophyseal peptide hormones oxytocin and vasopressin act to mediate human social behavior – they affect trust and social relationships and have an influence on avoidance responses. Describing the evolutionary roots of the effects that these neuropeptides have on behavior, this book examines remarkable parallel findings in both humans and non-human animals. The chapters are structured around three key issues: the molecular and neurohormonal mechanisms of peptides; phylogenetic considerations of their role in vertebrates; and their related effects on human behavior, social cognition, and clinical applications involving psychiatric disorders such as autism. A final chapter summarizes current research perspectives and reflects on the outlook for future developments. Providing a comparative overview and featuring contributions from leading researchers, this is a valuable resource for graduate students, researchers, and clinicians in this rapidly developing field.

Brain Mechanisms Theoretically Underlying Extremes of Social Behaviors: The Best and the Worst

The best, most pleasant forms of social behaviors amongst humans are characterized by a degree of altruism, sometimes reciprocal altruism, that has been encouraged universally by institutions that promote civil behavior. Here we review a surprisingly parsimonious neuroscientific theory of howhumansmanage to behave according to the “golden rule.” This theory, while allowing the understanding of pro-social behavior, also leads to a consideration of the neural mechanisms underlying aggression and abnormal social behavior, such as autistic behavior. Here we theorize that damagingly high levels of inputs from ascending CNS arousal systems to the amygdala heighten social anxiety in a manner that increases the chance of autistic behavior.