Some biochemicals in the brain apparently affect behavior; for example, a high level of the amine compound serotonin has been linked to aggression in a wide range of both vertebrate and invertebrate species. It is very difficult in the complex brain of vertebrate animals to study the way in which particular chemicals affect the function of particular single nerve cells, or neurons. In contrast, some invertebrate animals have limited numbers of large identifiable neurons, allowing analysis of complex behavioral processes at the level of the precise cells thought to be involved. This collaborative work in three different laboratories exploits the well-studied behavior of crayfish and the very accessible nervous system of these animals, as a model system. A variety of behavioral, pharmacological, molecular and physiological approaches are used to determine how amine compounds modulate the aggressive activity of dominant and non-dominant animals in their social hierarchies, and how particular amine- containing nerve cells are important in these behaviors. Results from this work will be fundamental to understanding how compounds that are used by certain cells as neural transmitters also can have effects on modulating behavior. By clarifying the roles of amines in complex behavioral processes, such as aggression in the nervous systems of animals far more complex than this model system, the results will have an impact beyond cellular neuroscience and neuroethology to other areas of behavior neuroscience and psychology.
