Male songbirds learn their songs by imitating adult conspecifics. Auditory neurons in the central vocal control system respond preferentially to the learned song, suggesting special perceptual process for the bird's own song. The Bengalese finch is a species of songbirds that sings complex song. To understand the relationship between auditory perception and neural analyses of the self-produced songs, we prepared modified songs as stimuli and compared the results of electrophysiological experiments and operant discrimination tasks.
Four song stimuli were edited: normal song played forward (FOR); song played backward (REV); globally reversed song in which the order of each song element was reversed (OREV); and locally reversed song in which global order of song notes remained unchanged but local temporal direction of each song note reversed (LREV).
In the operant experiment, birds were trained to peck for FOR and not to peck for REV. OREV and LREV were used as prove stimuli. Results suggested when trained with the self-produced song, the bird treated LREV as similar to the self-produced FOR song but when trained with a conspecific song they treated OREV as more similar to the trained song (Okanoya et al 2000).
In the electrophysiological experiment, birds were anaesthetized and each of the above songs was played while multiunit recordings were made from the nucleus HVc, the higher vocal center. The strongest response was obtained by FOR, followed by OREV. No response was obtained by REV and LREV (Nakamura and Okanoya, 2001). Thus, response properties of the HVc neurons describe only small part of auditory perception. To understand the perception at the level of individual would require an integration of physiological data recorded from several sites of the auditory vocal system. (Supported by JST)

OKANOYA, Kazuo
Department of Cognitive and Information Sciences
Faculty of Letters, Chiba University
1-33 Yayoi-cho, Inage-ku,
Chiba-city 263-0022, JAPAN,
okanoya@cogsci.L.chiba-u.ac.jp