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Hofman, P. M., Van Riswick, J. G. A., & Van Opstal, A. J. (1998). Relearning sound localization with new ears. Nature Neuroscience, 1(5), 417–421. 
Added by: Mark Grimshaw-Aagaard (2/2/14, 11:43 AM)   
Resource type: Journal Article
Peer reviewed
BibTeX citation key: Hofman1998
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 Categories: General
Keywords: Localization, Location of sound, Neuralplasticity, Psychoacoustics, Psychology
Creators: Hofman, Van Opstal, Van Riswick
Collection: Nature Neuroscience		 Views: 3/806
Abstract
Because the inner ear is not organized spatially, sound localization relies on the neural processing of implicit acoustic cues. To determine a sound’s position, the brain must learn and calibrate these cues, using accurate spatial feedback from other sensorimotor systems. Experimental evidence for such a system has been demonstrated in barn owls, but not in humans. Here, we demonstrate the existence of ongoing spatial calibration in the adult human auditory system. The spectral elevation cues of human subjects were disrupted by modifying their outer ears (pinnae) with molds. Although localization of sound elevation was dramatically degraded immediately after the modification, accurate performance was steadily reacquired. Interestingly, learning the new spectral cues did not interfere with the neural representation of the original cues, as subjects could localize sounds with both normal and modified pinnae.
  
Notes
Temporary acquisition of new pinna spectral transfer functions related to elevation localization when humans had pinnae distorted with molds.
  1. No training and pinnae molds in place for 6 weeks
  2. Elevation localization disrupted at first then gradually improved over several days
  3. After 6 weeks, results as before molds were in place. Results did not change with removal of the molds at this point
  4. After 6 weeks, the learned elevation localization immediately returned each time molds were re-inserted but with gradually diminishing effect
  5. Implication: brain maintains multiple sets of pinna spectral transfer functions and can choose between them

 Authors make the claim that visual spatial feedback aids (and may be most important) in relearning elevation localization (e.g. ventriloquism effect) but this contrasts with the results of experiments in ferrets (Kacelnik, O., Nodal, F. R., Parsons, K. H., & King, A. J. (2006)).


Added by: Mark Grimshaw-Aagaard  Last edited by: Mark Grimshaw-Aagaard