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Resolution of interaural time differences in the avian sound localization circuit-a modeling study
Brian J Fischer1, Armin H Seidl2
1Department of Mathematics, Seattle University Seattle, WA, USA.
Frontiers in Computational Neuroscience
|September 11, 2014
Summary
Interaural time differences (ITDs) are crucial for sound localization. Our model shows avian brainstem neurons can resolve microsecond ITDs at high frequencies, but not low ones, suggesting frequency-dependent coding strategies.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Computational Neuroscience
Background:
- Interaural time differences (ITDs) are vital cues for sound localization and segregation.
- The avian auditory brainstem, specifically nucleus laminaris (NL), is a key model for studying ITD detection.
- Neurons in NL receive binaural auditory input from the cochlear nucleus magnocellularis (NM) and compare precise timing.
Purpose of the Study:
- To model the ITD sensitivity of single NL neurons.
- To determine the minimum resolvable ITD for NL neurons.
- To understand how ITD resolution varies with frequency and its implications for sound localization.
Main Methods:
- Computational modeling of single NL neuron ITD sensitivity.
- Analysis of previously published neurophysiological data.
- Calculation of minimum resolvable ITD based on model parameters.
Main Results:
- Single NL neurons have limited ITD resolution at very low frequencies, insufficient for natural ITDs.
- For frequencies above 1 kHz, calculated ITD resolutions approach 10 μs, within the natural range.
- Different segments of the ITD tuning curve provide varying levels of ITD resolution.
Conclusions:
- A place code may be used for sound localization above 500 Hz.
- The slope of the ITD tuning curve is likely used for ITD discrimination at low frequencies.
- Results define the temporal precision required for binaural input processing in the avian auditory system.
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