Studies of Neuromodulation of Oscillatory Systems in Aplysia, by Means of Genetic Algorithms

Abstract

Neural modeling methods were used to obtain insights into the role of neuromodulatory cotrans mitters. Although the work was guided by specific experimental observations on feeding in Aplysia, it was meant as a more general treatment of behavioral systems. Genetic algorithms were used to evolve the parameters needed to permit a simple two-neuron circuit to oscillate and contract mus cles that execute rhythmic feeding responses. The evolved circuits were found to possess a number of "emergent" properties not specifically selected for. The fitness of the circuit decreased under a variety of conditions, particularly when the rate of the rhythmic program increased. The fitness of the system could be restored when an autoregulatory cotransmitter system was added and served to dynamically alter the parameters of the muscles that generated the behavior.