Related Experiment Videos
The evolution of temporal processing in the medial superior olive, an auditory brainstem structure
1Max-Planck-Institute of Neurobiology, Am Klopferspitz, Martinsried, Germany. bgrothe@neuro.mpg.de
Progress in Neurobiology
|April 25, 2000
Summary
The medial superior olive (MSO) processes temporal cues for pattern recognition in bats, not sound localization. Its coincidence detection mechanism may have been a pre-adaptation for later auditory functions in larger mammals.
Area of Science:
- Neuroscience
- Auditory processing
- Evolutionary biology
Background:
- The medial superior olive (MSO) is a mammalian auditory brainstem structure.
- Traditionally, the MSO was believed to exclusively process interaural time differences (ITDs) for low-frequency sound localization.
Purpose of the Study:
- To propose an alternative concept linking neuronal structures to processing rules rather than specific functions.
- To investigate the function of the MSO in mammals that do not rely on low-frequency sound localization.
Main Methods:
- Analysis of MSO function in bats.
- Recordings from the bat MSO to examine temporal cue processing.
Main Results:
- The bat MSO processes temporal cues in the millisecond and sub-millisecond range using monaural or binaural inputs.
- This processing is linked to pattern recognition and echo suppression, not sound localization.
- The underlying coincidence detection mechanism creates an epiphenomenal ITD sensitivity.
Conclusions:
- Neuronal structures may be governed by processing rules that can serve different functions across species and evolutionary stages.
- The MSO's ITD sensitivity in bats is likely a pre-adaptation, later co-opted for low-frequency sound localization in larger mammals.
- The MSO's core processing rules remained consistent, while its function evolved.