THE COMPUTATIONAL LEECH

The local bending reflex of the leech computes a well-defined sensorim otor input-output function in which each of several unique patterns of sensory input elicits a unique pattern of motoneuron activity. Intern eurons in the reflex respond to most input patterns and contribute to most motor patterns, suggesting a distributed processing mechanism for the reflex. This suggestion is supported by models in which connectio n strengths are adjusted by a neural network optimization algorithm to reproduce the local bending input-output function. In addition, compu tational parallels between the local bending network and the perceptro n, a major class of artificial neural networks, brings the functional role of local bending interneurons into question and suggests new phys iological experiments.