Meeting Abstract
Serotonin (5-HT) modulates agonistic behavior in crustaceans. However, the exact effect of 5-HT on social behavior has been difficult to determine because 5-HT modulates multiple neural circuits, its effects are concentration dependent and may reflect individual social history. Most studies examining the role of 5-HT in social behavior have used a simplified social paradigm of two individuals, a dominant and a subordinate; however, in nature, animals form social networks where they can be dominant to some individuals and subordinate to others. We examined how 5-HT modulates social behavior in a social network of the crayfish Orconectes obscurus. Fifteen crayfish were placed in an aquarium to establish social networks of dominant, intermediate, and subordinate individuals (n = 5 groups). Once social hierarchy stabilized, animals within a network were injected with 5-HT (0.002mM, 0.02mM, 0.2mM). Following injections, each animal was isolated to examine postural changes and activity. Then animals were returned to their network and monitored for changes in aggression and hierarchical shifts. Our preliminary results suggest that sensitivity to 5-HT reflects social dynamics. Subordinate animals produced a high, flexed posture in response to all three 5-HT concentrations, while the postures of dominant individuals were more variable and only the highest 5-HT concentration generated a high posture universally. In subordinates, 5-HT stimulated a high posture, but had no impact on aggression. In dominant individuals, the highest aggression was observed in response to the lowest dose. Intermediate individuals exhibited posture and aggression responses intermediate to the responses seen in dominants and subordinates. Our data suggest that sensitivity to 5-HT reflects social experience and complex social environment.
