Population coding of song element sequence in the songbird brain nucleus HVC

Abstract

Birdsong is a complex vocalization composed of various song elements organized according to sequential rules. To reveal the neural representation of song element sequence, we recorded the neural responses to all possible element pairs of stimuli in the Bengalese finch brain nucleus HVC. Our results show that each neuron has broad but differential response properties to element sequences. We calculated the time course of population activity vectors and mutual information between auditory stimuli and neural activities. The clusters of population vectors responding to second elements had a large overlap, whereas the clusters responding to first elements were clearly divided. At the same timing, confounded information also significantly increased. These results indicate that the song element sequence is encoded in a neural ensemble in HVC via population coding.