Origin of infrasound sensitive neurones in the papilla basilaris of the pigeon: an HRP study.

Infrasound sensitive afferent fibres recorded in the pigeon cochlear ganglion were marked by intracellular injections of horseradish peroxidase (HRP). All stained fibres were found to innervate hair cells in the basilar membrane between 90 and 950 microns from its apical end. No fibres to the macula lagenae were found. Nine of the 10 completely stained fibres contacted hair cells located abneurally on the free basilar membrane, the tenth ended over the neural limbus near its abneural border. All fibres innervated between two and nine hair cells. This is in contrast to common auditory fibres in the bird that were reported to innervate only one hair cell located neurally over the neural limbus. This paper, therefore, demonstrates, for the first time, physiologically defined fibres that do not end on 'inner' hair cells.