The CNS (right) has intrinsic dynamics, schematized here by the blue and red circles and the arrows of interconversion between them that may represent, for example, the dynamics of the evolution toward ingestive and egestive steady states in the Aplysia feeding CPG that are described in the Results. These CNS dynamics then complement, in a sense explored in this paper, the structure and dynamics of the environment relevant to the production of adaptive behavior (left). The CNS and the environment are bidirectionally coupled. The CNS perceives the true stimuli present in the environment, but only through noisy sensory channels (left to right arrow). The CNS then generates the behavior in, and thereby modifies, the environment (right to left arrow). For simplicity, all noise within the system is lumped here, as in the modeling in this paper, into just one sensory noise source. The performance of the adaptive behavior emerges from the operation of the entire coupled system of both the CNS and the environment.