Repeated exposure to a tone transiently alters spectral tuning bandwidth of neurons in the central nucleus of inferior colliculus in juvenile rats

Early acoustic experience changes tonal frequency tuning in the inferior colliculus (IC) and the primary auditory cortex. The contributions of IC plasticity to cortical frequency map reorganization are not entirely clear. While most cortical plasticity studies exposed animals to pulsed tones, studies of IC plasticity used either noise or a continuous tone. Here we compared the effects of repeated exposure to single-frequency tone pips on cortical and IC frequency representations in juvenile rats. We found that while tone exposure caused a long-lasting increase in cortical representations of the exposure frequency, changes to IC neurons were limited to a transient narrowing of tuning bandwidth. These results suggest that previously documented cortical frequency map reorganization does not depend on similar changes in the subcortical auditory nuclei.

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► Rat pups were exposed to pulsed tone from postnatal days 9 to 25.
► Exposure did not alter the frequency map in the central nucleus of the inferior colliculus (ICC).
► Exposure led to transient narrowing of the tuning bandwidth in the ICC.
► Exposure changed the frequency map in the primary auditory cortex.
► Conclusion: cortical map reorganization is not due to subcortical changes.