Persistence of Past Stimulations: Storing Sounds within the Inner Ear

• Published in: Biophysical journal 2011-04, Vol.100 (7), p.1627-1634
• Main Authors: Zheng, Jiefu, Ramamoorthy, Sripriya, Ren, Tianying, He, Wenxuan, Zha, Dingjun, Chen, Fangyi, Magnusson, Anna, Nuttall, Alfred L., Fridberger, Anders
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; acoustics; Action Potentials - physiology; Animals; Auditory stimuli; Basilar Membrane - physiology; Biological Systems and Multicellular Dynamics; Cells; Cochlear implants; Ear, Inner - physiology; ears; Ears & hearing; emissions; energy; Guinea Pigs; hearing; hearing disorders; Mathematical models; Membranes; Motion; Organ of Corti - physiology; Rodents; Sound; Time Factors; Vibration
• ISSN: 0006-3495; 1542-0086; 1542-0086
• DOI: 10.1016/j.bpj.2011.02.025

Tones cause vibrations within the hearing organ. Conventionally, these vibrations are thought to reflect the input and therefore end with the stimulus. However, previous recordings of otoacoustic emissions and cochlear microphonic potentials suggest that the organ of Corti does continue to move after the end of a tone. These after-vibrations are characterized here through recordings of basilar membrane motion and hair cell extracellular receptor potentials in living anesthetized guinea pigs. We show that after-vibrations depend on the level and frequency of the stimulus, as well as on the sensitivity of the ear. Even a minor loss of hearing sensitivity caused a sharp reduction in after-vibration amplitude and duration. Mathematical models suggest that after-vibrations are driven by energy added into organ of Corti motion after the end of an acoustic stimulus. The possible importance of after-vibrations for psychophysical phenomena such as forward masking and gap detection are discussed.