Journal of Neuroscience, Vol 11, 1210-1223, Copyright © 1991 by Society for Neuroscience
Mutual inhibition among neural command systems as a possible mechanism for behavioral choice in crayfish
DH Edwards
Department of Biology, Georgia State University, Atlanta 30302-4010.
Mutual inhibition among behavioral command systems frequently has been
suggested as a possible mechanism for switching between incompatible
behaviors. Several neural circuits in crayfish that mediate incompatible
behaviors have been found to interact through inhibition; this accounts for
increased stimulus threshold of one behavior (e.g., escape tailflip) during
performance of others (eating, walking, defense). To determine whether
mutual inhibition between command systems can provide a mechanism that
produces adaptive behavior, I developed a model crayfish that uses this
mechanism to govern its behavioral choices in a simulated world that
contains a predator, a shelter, and a food source. The crayfish uses energy
that must be replaced by eating while it avoids capture by the predator.
The crayfish has seven command systems (FORAGE, EAT, DEFENSE, RETREAT,
ESCAPE, SWIM, HIDE) that compete through mutual inhibition for control of
its behavior. The model crayfish was found to respond to changing
situations by making adaptive behavioral choices at appropriate times.
Choice depends on internal and external stimuli, and on recent history,
which determines the pattern of those stimuli. The model's responses are
unpredictable: small changes in the initial conditions can produce
unexpected patterns of behavior that are appropriate alternate responses to
the stimulus conditions. Despite this sensitivity, the model is robust; it
functions adaptively over a large range of internal and external parameter
values.
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