Sensory feedback can coordinate the swimming activity of the leech

Previous studies showed that sensory feedback from the body wall is importa nt and sometimes critical for generating normal, robust swimming activity i n leeches. In this paper, we evaluate the role of sensory feedback in inter segmental coordination using both behavioral and physiological measurements . We severed the ventral nerve cord of leeches in midbody and then made vid eo and in situ extracellular recordings from swimming animals. Our electrop hysiological recordings unequivocally demonstrate that active intersegmenta l coordination occurs in leeches with severed nerve cords, refuting Schulte r's (1933) earlier conclusions that sensory feedback cannot coordinate swim ming activity Intersegmental coordination can in fact be achieved by sensor y feedback alone, without the intersegmental interactions conveyed by the n erve cord.