Lecture 15 Model Systems
Drosophila courtship behavior
The courtship behavior of Drosophila is an interesting system for genetic study because, like all sexual behavior, it is innate, making it a convenient system from which to obtain links between genotype and behavior. Visual, olfactory, gustatory, and auditory sensory cues produce a robust and stereotyped courtship behavior in Drosophila males. Wildtype males consistently orient themselves near the female, "tap" them and sing to them before attempting copulation. Studies of this behavior have investigated the strong role of the fruitless gene, which encodes for a set of male-specific transcription factors Fru^M in males whose action controls their sexual behavior (Manoli et al. 2005).
Different species of voles exhibit robust stereotyped sexual behavior, much like the courtship rituals of Drosophila males. Specifically, prairie voles are found to spend more time huddling after mating and cohabitating with a sexual mate than meadow voles, which tend to exhibit more independence. This pair bonding behavior is attributed to the roles of neuropeptides oxytocin and vasopressin. Oxytocin is exhibited in the female (it also is responsible for mother/infant bonding) and vasopressin is exhibited in the male (vasopressin is also associated with male social responses such as aggression, scent marking, and courtship). The neuropeptides are released after mating, and can induce pair-bonding even when sexual activity is not present. The bonding is thought to be due to the intersection of social discrimination circuits from the olfactory pathway to the oxytocin/vasopressin and dopamine reward systems. Prairie voles, consequently, possess more vasopressin V1a receptor than meadow voles in the ventral pallidum of the ventral forebrain.
Lecture 15 Techniques
Retrograde pseudorabies virus
Pseudorabies can be used as a transneuronal marker that infects in the retrograde direction: it infects and enters the presynaptic neuron. As a result, it can be used to study the connections between neurons.
Recording in behaving mice
Recording in behaving mice enables recording cells while mice perform particular tasks. In Lecture 15, we discussed recording AOB mitral cells. An electrode is placed into the accessory bulb mitral cell layer. Firing of neurons is recorded and connected to an amplifier. A microdrive is likewise connected to a cable and commutator to facilitate the animal's movement through its environment. AOB mitral cells were found to have especially high firing rates when in contact with the anesthetized conspecifics, specifically pheromones in the face and anogenital regions.