26 October 1999
Social Climbing Crustaceans
by Kate Melville 
Crayfish show that social aspirations might change the way your brain works The latest neuroscience research shows that. According to a In a new study from Georgia State University conducted by biologists Don Edwards and Joanne Drummond, seems to indicate that brains change along with behavior on the social ladder. Their project looked at how dominant and subordinate crayfish react to stressful situations - by responding to the same brain chemical in different ways depending on their social standing. Why are crayfish so interesting, it's simple if you can remember what seratonin is? Doesn't ring a bell, well neurobiologists study cray brains because they contain serotonin, one of several substances known to affect mood and aggression. Crayfish might taste great in a fancy restaurant, but they are quite nasty and fight a lot. At the end of their bouts one crayfish becomes dominant over the other. Edwards' and Drummond's research, indicates that serotonin-containing crayfish nerve cells respond differently to natural stimuli in socially dominant and subordinate animals after a fight.
Thwy founs that the nerve cells that trigger escape behavior are inhibited by serotonin in subordinate crayfish, but these same neurons are made more responsive by serotonin in dominant animals. What causes this may be an imbalance between excitatory and inhibitory serotonin receptors in the crayfishes' escape nerve cells. The changes the effect of serotonin take about two weeks to develop following the fight that determines the crayfish's social status, and are by and large completely reversible (this means that if the loser can win, serotonin will revert to being excitatory). Whether or not this will lead to any changes in therapies that try to impact on seratonin levels is too early to tell, but if your taking Prozac stay away from crayfish.
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