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Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Estimated cochlear delays in low best-frequency neurons in the barn owl cannot explain coding of interaural time
Martin Singheiser1, Brian J Fischer, Hermann Wagner
1Institute for Biology II, Department of Zoology and Animal Physiology, Rheinisch-Westfälische Technische Hochschule Aachen, Aachen, Germany. martin@bio2.rwth-aachen.de
Journal of Neurophysiology
|August 13, 2010
Summary
Cochlear delays do not explain how barn owls process low-frequency sound localization. This study found that the stereausis model
Area of Science:
- Auditory Neuroscience
- Bioacoustics
- Animal Behavior
Background:
- The role of low-frequency hearing (<3 kHz) in barn owl sound localization remains unclear.
- Interaural time difference (ITD) is crucial for sound localization, but its neural representation in low frequencies is not well understood.
- The stereausis model proposes cochlear delays as a mechanism for ITD representation.
Purpose of the Study:
- To investigate whether cochlear delays explain the neural representation of ITD in the low-frequency range of barn owl hearing.
- To test the predictions of the stereausis model in low-frequency sensitive neurons.
- To determine the primary mechanism for ITD processing in barn owls at frequencies below 3 kHz.
Main Methods:
- Recorded neural responses in the central nucleus of the inferior colliculus of barn owls.
- Stimulated neurons with varying interaural time differences (ITDs) at low frequencies.
- Analyzed frequency response functions and compared neural data with the stereausis model's predictions.
Main Results:
- Neural responses varied with ITD, with array-specific ITDs widely distributed.
- The stereausis model's predictions were not supported by the data from low best-frequency neurons.
- Cochlear delays were found to be insufficient to explain the best ITD representation in these neurons.
Conclusions:
- Cochlear delays are not the primary mechanism for representing best ITD in low-frequency sensitive neurons of the barn owl.
- Alternative mechanisms may underlie sound localization in the low-frequency range for barn owls.
- Further research is needed to elucidate the neural basis of low-frequency sound processing in this species.
Related Concept Videos
01:13The Cochlea
The cochlea is a coiled structure in the inner ear that contains hair cells—the sensory receptors of the auditory system. Sound waves are transmitted to the cochlea by small bones attached to the eardrum called the ossicles, which vibrate the oval window that leads to the inner ear. This causes fluid in the chambers of the cochlea to move, vibrating the basilar membrane.
01:21Perceiving Loudness, Pitch, and Location
The human brain perceives pitch through two primary mechanisms reflected in place theory and frequency theory. Each mechanism describes how sound waves are interpreted as specific pitches by the brain, offering insights into the intricate processes of auditory perception.
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
Place theory, or place coding, suggests that different pitches are heard because various sound waves activate specific locations along the cochlea's basilar membrane. The brain determines the pitch of a sound by identifying...
01:15Auditory Pathway
Auditory pathways constitute the complex neural circuits responsible for transmitting and interpreting auditory information from the peripheral auditory system to the brain. Sound waves are initially captured by the outer ear, funneled through the ear canal, and reach the tympanic membrane (eardrum). These vibrations are transmitted via the middle ear's ossicles to the inner ear's cochlea.
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
When viewed cross-sectionally, the cochlea reveals the scala vestibuli and scala tympani flanking the...
01:22Hair Cells
Hair cells are the sensory receptors of the auditory system—they transduce mechanical sound waves into electrical energy that the nervous system can understand. Hair cells are located in the organ of Corti within the cochlea of the inner ear, between the basilar and tectorial membranes. The actual sensory receptors are called inner hair cells. The outer hair cells serve other functions, such as sound amplification in the cochlea, and are not discussed in detail here.
01:31Hearing
When we hear a sound, our nervous system is detecting sound waves—pressure waves of mechanical energy traveling through a medium. The frequency of the wave is perceived as pitch, while the amplitude is perceived as loudness.