The Shaping of Sex Behavior, Odor Perception, and Neural Activation by Sex Experience: The Role of the Bed Nucleus of the Stria Terminalis’s Projections to the Nucleus Accumbens
Odor, sex, & neural activation
Haverford College. Department of Psychology
Place of Publication
Table of Contents
Research has demonstrated that drugs of abuse lead to changes in both behavior and in neural activation. Drugs of abuse activate the same reward pathway in the brain as natural rewards, such as sex behavior. In order to better understand drug addiction, it is important to study how behavior and the brain change in response to experience with natural rewards. In the model organism of the Syrian hamster, sex behavior depends critically on the processing of odors. The bed nucleus of the stria terminalis (BNST), the medial amygdala (ME), and the medial preoptic area (MPOA) all process conspecific odors that help guide and reward sex behavior. There is plasticity in this brain region, and in particular sexual experience has been shown to modify the BNST’s involvement in opposite sex odor preference. It is unclear whether the number of activated projections is modified by experience. Thus, this research investigated how sex experience may change the neural response to a sexual odor in BNST neurons that project to the nucleus accumbens (NAc) in male Syrian hamsters. Hamsters were divided into a group that received no sexual experience or into a group that received eight ten-minute sexual experiences with a female hamster. Both groups of hamsters were injected with a retrograde tracer, Cholera Toxin B (CTB), into the NAc. The groups were given an odor experience and sacrificed. Immunohistochemistry was used to visualize CTB as well as c-Fos, a measure of recent neuronal activity. However, the neurons were not able to be visualized due to a hypothesized problem with over-fixation of the tissue. The research demonstrated that the number of mounts, intromissions, ejaculations, and the efficiency rate (mounts/intromissions) did not significantly differ over repeated sexual experiences. Future work utilizing correct staining of the tissue will help provide an understanding of how experiences that occur as part of an individual's everyday life can change the brain's reward system and impact future behavior.