locust chordotonal organ coding for proprioceptive and acoustic stimuli

A chordotonal organ in the prothoracic segment of a locust combines features of a proprioceptive mechanoreceptor and an acoustic organ. This organ is closely associated with the tracheal system in the neck. The central nervous projections of the sensory cells contact neuropiles in all thoracic ganglia with the most dense arborizations in the metathoracic ganglion in close proximity, and even with some overlap, to the projections of tympanic fibres. Physiological experiments show that this organ responds to mechanical displacement of its receptor apodeme and, in addition, to acoustic stimulation via either a region of the cervical membrane which may act as a functional tympanic membrane, or via the tracheal system.