Showing papers by "Franz Goller published in 2006"

Physiological insights into the social-context-dependent changes in the rhythm of the song motor program.

Abstract: Precisely timed behaviors are central to the survival of almost all organisms. Song is an example of a learned behavior under exquisite temporal control. Song tempo in zebra finches (Taeniopygia gu...

Nonlinear model predicts diverse respiratory patterns of birdsong.

Abstract: A central aspect of the motor control of birdsong production is the capacity to generate diverse respiratory rhythms, which determine the coarse temporal pattern of song. The neural mechanisms that underlie this diversity of respiratory gestures and the resulting acoustic syllables are largely unknown. We show that the respiratory patterns of the highly complex and variable temporal organization of song in the canary (Serinus canaria) can be generated as solutions of a simple model describing the integration between song control and respiratory centers. This example suggests that subharmonic behavior can play an important role in providing a complex variety of responses with minimal neural substrate. The characteristic temporal patterns of birdsong, with alternating sound and silence, arise primarily from the activity of respiratory muscles [1]. Sound is typically generated during expiration as the elevated air pressure drives the airflow that induces phonation. Silent periods in between song elements correspond to short inspirations (minibreaths) unless the sound pulse rate is very high [2,3]. A remarkable capacity to rapidly switch between expiration and inspiration gives rise to the complex temporal song structure and at the same time allows birds to sing long, uninterrupted songs. Song in the Waterslager canary is a long sequence of distinct syllables, each of which is repeated a variable number of times (phrase) before a switch to a new syllable type occurs. Syllable repetition rate varies between phrase types and can be as high as 30 Hz for syllables that are followed by a minibreath and even greater than 60 Hz for phrases which are sung during a sustained expiration (pulsatile syllables) [4,5]. Song is a learned behavior, and it is unknown how the motor gestures for different syllable types, with remarkably different rhythms, are represented in the central motor program. A song is built out of a diversity of syllables. Each syllable is generated by the vocal organ when activated by a specific pressure pattern. The different pressure patterns could be generated when the appropriate muscles are activated either by different neural populations, or by a unique neural population displaying a variety of activity patterns. The latter scenario is possible since neurons behave as nonlinear devices. Nonlinear systems are known to exhibit qualitatively different behaviors (with strict topological restrictions) under different parameters. Therefore, a variety of temporal patterns can be generated by a single system under different operational regimes. Here we use a variety of tools from nonlinear dynamics to show that the temporal features of air sac pressure data recorded from singing canaries can be reproduced with such a simple model.

Aspects of syringeal mechanics in avian phonation

Abstract: The vocal organ of birds, the syrinx, is formed by modified cartilages of the trachea and bronchi. Recently, the use of thin, flexible endoscopes has made direct observation of the syrinx possible in situ. The effects of direct muscle stimulation on the syringeal aperture identified adductor and abductor muscles, confirming results from electromyographic studies. Endoscopic observations also revealed the dynamics of syringeal reconfiguration during phonation. In songbirds, phonation is initiated by rostrad movement and stretching of the syrinx together with simultaneous movement of the medial and lateral labia into the bronchial lumen where they form a narrow slot. The medial tympaniform membranes play a minor role in vocalization as their removal causes only small changes to song. In the tracheal syrinx of the pigeon, sound production is initiated by almost full adduction of the lateral tympaniform membranes into the tracheal lumen, where they bulge rostrally during phonation. Endoscopic observation combined with vibration detection by laser light suggests that the avian sound generating mechanism is a pulse-tone mechanism similar to that in the human larynx, with the labia (or lateral tympaniform membranes) forming a pneumatic valve. A numerical, two-dimensional model of the pigeon syrinx is proposed

S26-1 Respiratory dynamics and syllable morphology in songbirds

Abstract: Song in birds is produced as air flows past the vibratory structures of the syrinx typically during expiration. Whereas there is detailed information about bilateral syringeal contributions to sound production, little is known of the interactions of air sac pressure and airflow, and how these affect sound frequency and sound amplitude. We studied air sac pressure and airflow during song in brown-headed cowbirds, cardinals and zebra finches, three species with acoustically dissimilar songs. Results revealed no consistent relationship between air sac pressure and airflow during song syllables with different acoustic structure, suggesting that adjustments in syringeal resistance play an important role in airflow regulation. In cowbirds and zebra finches, high frequency sounds were produced with higher air sac pressure. In these same species, sound amplitude appears to be greater for high than low frequency sounds, suggesting greater efficiency in transforming fluid dynamic energy into acoustic energy.

S26-3 Aspects of syringeal mechanics in avian phonation

Abstract: The vocal organ of birds, the syrinx, is formed by modified cartilages of the trachea and bronchi. Recently, the use of thin, flexible endoscopes has made direct observation of the syrinx possible in situ. The effects of direct muscle stimulation on the syringeal aperture identified adductor and abductor muscles, confirming results from electromyographic studies. Endoscopic observations also revealed the dynamics of syringeal reconfiguration during phonation. In songbirds, phonation is initiated by rostrad movement and stretching of the syrinx together with simultaneous movement of the medial and lateral labia into the bronchial lumen where they form a narrow slot. The medial tympaniform membranes play a minor role in vocalization as their removal causes only small changes to song. In the tracheal syrinx of the pigeon, sound production is initiated by almost full adduction of the lateral tympaniform membranes into the tracheal lumen, where they bulge rostrally during phonation. Endoscopic observation combined with vibration detection by laser light suggests that the avian sound generating mechanism is a pulse-tone mechanism similar to that in the human larynx, with the labia (or lateral tympaniform membranes) forming a pneumatic valve. A numerical, two-dimensional model of the pigeon syrinx is proposed.