Paul Baker
Animal Life
Article Summary

 Neurobiologist Donald Edwards of Georgia State University and his colleagues Shih- Rung Yeh and Russell Fricke provide the first direct evidence that social dominate/subordinate behavior of crayfish causes changes in the crayfish’s nervous systems.  The implications go beyond crayfish.  The Edward’s group findings are “the first time that one has been able to link a social phenomenon to a change in a particular identified synapse.”  Researchers have suspected this might occur in higher animals.  The research found that serotonin injections caused crayfish to assume the aggressive posture characteristic of dominant animals.  Serotonin is the substance that other researchers had linked to aggressive behavior in lobsters and crayfish 15 years ago.  This finding caused several labs to study serotonin’s effect on behaviors like the tail-flip reflex.  Russell Fricke, one of the researchers, found that when he injected serotonin into young crayfish, it inhibited the tail-flip reflex in some, while enhancing it in others.  That suggested that social status might have influenced the results.  Yeh found that serotonin enhanced the excitability of the giant neurons from dominant crayfish, while it suppressed activity of the neuron from subordinate crayfish.  This indicated a biological change in the receptors through which serotonin effects.  The researchers study the specific pathways through which social position gets translated into cellular and molecular changes in the neuron.

 Barinaga, Marcia.  “Social Status Sculpts Activity Of Crayfish Neurons.”  Science.  Vol. 271 January 19, 1996: 290-291. -----------------------------7cefa2793c-- ˙