Neuronal number in song nucleus LMAN remains high in female zebra finches throughout development and in adulthood(In English)

摘要

Song learning and production in birds involve a discrete set of interconnected song nuclei in the avian brain. In species where only males sing, such as the zebra finch ( Taeniogygia guttata ), large sex differences are present in song system nuclei and the number of neurons is much smaller in females compared to males. Whereas it is assumed that this also applies to the lateral magnocellular nucleus of the anterior nidopallium (LMAN), a detailed analysis is still lacking. To close this gap and to learn more about the development of neuronal numbers in both sexes, we have quantified neuronal density and number on semithin sections in small time intervals using the disector-technique. In females, neither neuronal density nor number increased or decreased significantly between 10 days and adulthood at any time interval sampled, so that neuronal density and number remained high in adult females. In males, we found a strong decrease in neuron number very early in development as known from literature using non-stereological techniques, and an additional decrease in neuron number (57%) that lasts up to adulthood. Therefore, the total number of neurons in LMAN in adult birds was about 4 times higher in females than in males (p<0.001). The larger neuronal number in females may reflect the ability of keeping up a neuronal network that can be used throughout development and in adulthood, probably for tasks that may be related particularly to species-specific recognition tasks as it has been shown for this brain region in other passerine female birds [ A cta Zoologica Sinica 51(2): 257 – 267 , 2005].