Related Experiment Video
Updated: Jun 19, 2025
09:54
Morphological and Functional Evaluation of Ribbon Synapses at Specific Frequency Regions of the Mouse Cochlea
Published on: May 10, 2019
11.8K
The cochlear hook region detects harmonics beyond the canonical hearing range.
Kazuhiro Horii1, Bakushi Ogawa1,2, Noriko Nagase1,2
1Division of Biological Principles, Department of Physiology and Biophysics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1194, Japan.
PNAS Nexus
|July 26, 2024
Summary
Scientists discovered how guinea pigs hear ultrasound, finding that hair cells in the cochlea respond to high-frequency sounds. This research sheds light on ultrasonic hearing mechanisms and potential applications for hearing aids.
Area of Science:
- Auditory Neuroscience
- Bioacoustics
- Sensory Physiology
Background:
- Ultrasound, frequencies beyond human hearing, is perceived by some animals and has applications in brain activation and hearing aids.
- The physiological basis for ultrasonic hearing, especially in mammals, remains largely unexplored.
- Understanding ultrasonic perception is crucial for advancing audiology and neuroscience.
Purpose of the Study:
- To elucidate the physiological mechanism of ultrasonic hearing in mammals.
- To investigate the role of cochlear hair cells and the sensory epithelium in detecting ultrasound.
- To determine the frequency range and characteristics of ultrasonic sound detection in the cochlea.
Main Methods:
- Evoked auditory brainstem responses and cochlear microphonic potentials (CM) in guinea pigs exposed to ultrasound.
- In vivo optical nano-vibration analysis of the cochlear sensory epithelium.
- Electrophysiological recordings to assess mechano-electrical transduction in hair cells.
Main Results:
- Ultrasound above the typical hearing range elicits auditory brainstem responses and CM in guinea pigs.
- Cochlear hair cells exhibit active and nonlinear amplification of ultrasonic stimuli, synchronizing with the sound.
- The cochlear hook region resonates with ultrasound and its harmonics, detecting frequencies over two octaves beyond the normal hearing limit.
Conclusions:
- Mammalian cochlear hair cells are capable of responding to ultrasonic frequencies and their harmonics.
- The basal extreme of the cochlea, specifically the hook region, plays a key role in detecting high-frequency ultrasound.
- This study reveals a previously unknown mechanism for ultrasonic hearing, with implications for hearing aid technology and understanding sensory perception.
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