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- Title
Developmental fine-tuning of medial superior olive neurons mitigates their predisposition to contralateral sound sources.
- Authors
Sierksma, Martijn C.; Borst, J. Gerard G.
- Abstract
Having 2 ears enables us to localize sound sources by exploiting interaural time differences (ITDs) in sound arrival. Principal neurons of the medial superior olive (MSO) are sensitive to ITD, and each MSO neuron responds optimally to a best ITD (bITD). In many cells, especially those tuned to low sound frequencies, these bITDs correspond to ITDs for which the contralateral ear leads, and are often larger than the ecologically relevant range, defined by the ratio of the interaural distance and the speed of sound. Using in vivo recordings in gerbils, we found that shortly after hearing onset the bITDs were even more contralaterally leading than found in adult gerbils, and travel latencies for contralateral sound-evoked activity clearly exceeded those for ipsilateral sounds. During the following weeks, both these latencies and their interaural difference decreased. A computational model indicated that spike timing-dependent plasticity can underlie this fine-tuning. Our results suggest that MSO neurons start out with a strong predisposition toward contralateral sounds due to their longer neural travel distances, but that, especially in high-frequency neurons, this predisposition is subsequently mitigated by differential developmental fine-tuning of the travel latencies. Neurons in the medial superior olive are important for sound localization, as they are sensitive to the relative arrival time of sounds at both ears. This study reveals the developmental dynamics of this sensitivity, reporting that shortly after hearing onset these cells have a strong preference for contralateral leading sounds, which is fine-tuned towards sounds coming from the front in adulthood.
- Subjects
EAR; INTERAURAL time difference; DIRECTIONAL hearing; NEURONS; ACOUSTIC localization; SPEED of sound; OLIVE leaves
- Publication
PLoS Biology, 2024, Vol 22, Issue 4, p1
- ISSN
1544-9173
- Publication type
Article
- DOI
10.1371/journal.pbio.3002586