Avian Song Control :: Birds Bird Neorology Essays

Avian Song Control Bird songs continue to fascinate neurobiologists and neuroethologists because the development of song has been a popular model used to examine the role of environment on behavior. In most species, only male birds sing complex songs. Their vocalizations are the result of sexual dimorphism in the brain regions responsible for the production of song. However, this behavior is not genetically hardwired into the avian brain. Certain conditions must exist in order for male birds to successfully produce their species-specific song. Additionally, the neuronal circuitry and structure of the avian song system shows high levels of plasticity. If the brain and behavior are indistinguishable, then the structural differences in the avian brain are responsible for behavioral differences across the sexes. Nottebohm and colleagues identified six anatomically distinct regions of the forebrain involved in the production of song, which are arranged into two independent pathways, the posterior pathway, which controls song production, and the anterior pathway, which controls song learning. The collective unit is typically referred to as the vocal control region (VCR) (1) (2). Female birds sing rarely and this behavioral difference is reflective of the anatomy of the female avian brain. There are significant differences in the size of three neural areas involved in the production of song across the sexes, and a specific area, Area X, is present in the male and absent in the female. Additionally, the incorporation of radiolabeled testosterone in certain locations is different in males and females (3) (4). Scientists have been particularly interested in the origin of the structural differences in male and female songbirds. Research has suggested the importance of gonadal hormones, specifically testosterone in the production of song. It was observed that castration eliminated all song production (5). Additionally, when testosterone levels are low, there is not only a decrease in the production of song, but also a decrease in the size of some nuclei involved in song production (6). Further support for the necessity of testosterone for song production was demonstrated by Nottebohm (1980) when he injected female birds with testosterone, which lead to the production of song (7). This research has interesting implications regarding anatomical changes that may occur when an organism is chemically imbalanced. Disruptions in chemical equilibrium may alter brain structure and subsequently influence behavior. Nevertheless, not all research has supported the claim that testosterone is responsible for anatomical and behavioral differences between male and female songbirds. Avian Song Control :: Birds Bird Neorology Essays Avian Song Control Bird songs continue to fascinate neurobiologists and neuroethologists because the development of song has been a popular model used to examine the role of environment on behavior. In most species, only male birds sing complex songs. Their vocalizations are the result of sexual dimorphism in the brain regions responsible for the production of song. However, this behavior is not genetically hardwired into the avian brain. Certain conditions must exist in order for male birds to successfully produce their species-specific song. Additionally, the neuronal circuitry and structure of the avian song system shows high levels of plasticity. If the brain and behavior are indistinguishable, then the structural differences in the avian brain are responsible for behavioral differences across the sexes. Nottebohm and colleagues identified six anatomically distinct regions of the forebrain involved in the production of song, which are arranged into two independent pathways, the posterior pathway, which controls song production, and the anterior pathway, which controls song learning. The collective unit is typically referred to as the vocal control region (VCR) (1) (2). Female birds sing rarely and this behavioral difference is reflective of the anatomy of the female avian brain. There are significant differences in the size of three neural areas involved in the production of song across the sexes, and a specific area, Area X, is present in the male and absent in the female. Additionally, the incorporation of radiolabeled testosterone in certain locations is different in males and females (3) (4). Scientists have been particularly interested in the origin of the structural differences in male and female songbirds. Research has suggested the importance of gonadal hormones, specifically testosterone in the production of song. It was observed that castration eliminated all song production (5). Additionally, when testosterone levels are low, there is not only a decrease in the production of song, but also a decrease in the size of some nuclei involved in song production (6). Further support for the necessity of testosterone for song production was demonstrated by Nottebohm (1980) when he injected female birds with testosterone, which lead to the production of song (7). This research has interesting implications regarding anatomical changes that may occur when an organism is chemically imbalanced. Disruptions in chemical equilibrium may alter brain structure and subsequently influence behavior. Nevertheless, not all research has supported the claim that testosterone is responsible for anatomical and behavioral differences between male and female songbirds.