Distinct timescales for the neuronal encoding of vocal signals in a high-order auditory area
Distinct timescales for the neuronal encoding of vocal signals in a high-order auditory area The ability of the auditory system to selectively recognize categories of natural sounds while maintaining a degree of tolerance to variations within those categories is crucial for speech communication. To date, it remains unclear how the balance between tolerance and sensitivity to variations in acoustic signals is encoded at the neural level. Here, we investigate whether neurons in an area of the auditory cortex (high-level area) of the zebra finch, a species of songbird, are sensitive to natural variations in vocal signals by recording their responses to repeated exposures to identical and variant sound sequences. We used the songs of male birds, which are highly repetitive and exhibit only subtle acoustic variations between renditions. We found that these acoustic variations between songs did not affect the intensity of neural responses but modulated their temporal reliability. This suggests that auditory processing operates on a range of distinct timescales: a short one to detect variations in vocal signals, and longer ones that allow the bird for tolerance to acoustic variations in songs and encoding of the overall context in which sounds are emitted.
Distinct timescales for the neuronal encoding of vocal signals in a high-order auditory area. Aurore Cazala, Catherine Del Negro & Nicolas Giret.