Neural coding of timbre in birdsong

S. BOARI AND A. AMADOR

Mar del Plata, Buenos Aires

Conferencia; XXX Annual Meeting of the Society for Neuroscience Argentina; 2015

Sociedad Argentina de Neurociencias

Given two sounds of same pitch, loudness and duration, timbre is the acoustical property responsible of the sound´s identity. Timbre is a multidimensional attribute that is most elusive to describe. In humans, some of these dimensions have been identified and explored in psychoacoustics experiments, but an objective way to measure it is yet to be determined.In this work, we studied the contribution of attack time to the sound identity. Attack time is a well-established dimension of timbre: is the time it takes for the sound envelope to reach its maximum.Zebra finches (Taeniopygia guttata) present a remarkable opportunity to study timbre in complex vocalizations as they present a wide syllable repertoire and they have a large number of syllables with a rapid attack time and a slower decaying envelope. In addition, previous experimental evidence showed that telencephalic neurons in HVC respond in a highly selective fashion to auditory presentations of the Bird´s Own Song (BOS) while not responding to the reversed song. Therefore, we used HVC neural activity as a measure of BOS recognition. We generated a modified BOS in which the sound envelope of each syllable was reversed (MOD). This effectively switches the attack and decay times of each syllable while maintaining the rest of the acoustical properties intact. We have found that these changes in the attack time lead to a decrease in the neural response of HVC units, unveiling a neural representation of timbre in HVC.