EDWARDS, D.H.; KRASNE, F.B.: Modulation of crayfish escape reflexes II. Neuroethology of serotonergic modulation during dominance hierarchy formation.

Analysis of escape behavior during the formation of dominance hierarchies shows that GF escape can be either facilitated or inhibited, depending on the stage of development of a social order and on the status of the animal. Three stages of agonistic interaction are identified: (I). The initial period of escalating aggression by both animals that leads up to, but does not include, the decision of the subordinate to retreat. (II). The decision of the subordinate to retreat, signaled by a rapid series of GF and non-GF escapes, and followed by an early post-determination phase during which the new dominant harasses the new subordinate(s), which responds by escaping. . (III). A final state characterized by few aggressive interactions, but the subordinate avoids the dominant by retreating, and maintaining a low profile at the periphery of the living space. During phase I, GF escape is strongly inhibited in both prospective dominants and subordinates. During phase II, GF excitability increases substantially in subordinates as they escape from the dominant�s attacks and also increases somewhat in dominants. GF excitability then decreases between phases II and III to become lower in subordinates than in dominants. These differences can be explained by patterns of serotonergic and GABA-ergic modulation, and by changes in those patterns as a result of social experience.