| Description |
Glycosaminoglycans are carboyhydrate side chains of proteoglycans that have a myriad of biological functions. In the brain, these molecules are implicated in everything from development to plasticity to disease. Two of the main types of glycosaminoglycans (GAGs), heparan sulfate and chondroitin sulfate, have been implicated in both plasticity and learning; however, the exact role they play has remained unclear. One of the more interesting sensorimotor systems in the brain involves the learning and production of vocalizations. The goal of this work was to investigate the role GAGs play in two different aspects of this complex behavior, the neural control of vocal ontogeny and superfast muscle involvement in song production of zebra finch. In order to fully understand the role GAGs play in complex biological behaviors, such as vocalizations, it is imperative that the proper tools be synthesized, characterized, and produced for the study of these carbohydrates. Enzymes, specifically sulfated polymers and oligosaccharides, and small molecules provide unique opportunities to examine the role of GAGs. The use of enzymes in the song-specific nucleus, HVC, allowed the validation of the functionality of these enzymes in the model system of interest. Changes in stereotyped song were observed showing that GAG modulation could lead to alteration of a learned behavior. After this confirmation that GAGs were present and involved in song, small molecules called xylosides were used to examine the role of chondroitin sulfate iv biosynthesis during vocal ontogeny. Infusion of xyloside into RA (robust nucleus of the arcopallium), a nucleus important for vocal ontogeny, led to a change in the development of song. This implies that regulated biosynthesis of chondroitin sulfate during the critical period for vocal ontogeny is important. Lastly, the role of superfast syringeal muscles in song production was examined. Heparan sulfate degradation in these muscles alters the ability of the syrinx to modulate airflow. This change in muscle kinetics was correlated with significant, but temporary, differences in acoustic structure and frequency modulation while long-term differences showed aberrant syllable production. |
