DeVoogd T J, Pyskaty D J, Nottebohm F
Department of Psychology, Cornell University, Ithaca, New York 14853.
J Comp Neurol. 1991 May 1;307(1):65-76. doi: 10.1002/cne.903070107.
The caudal portion of the hypoglossal nucleus (tracheosyringeal, nXIIts) contains the motor neurons that innervate the syrinx in songbirds. It receives projections from telencephalic and midbrain nuclei that are necessary for song production. Its neurons concentrate androgens. The present study assesses the gross morphology of the hypoglossal nucleus in canaries. In this species song is more frequent, elaborate, and stereotyped in males than in females. Adult females respond to testosterone by developing a stereotyped song that is sung frequently. Song in male canaries is much more disrupted by damage on the left side of the song system than by damage on the right. We find anatomical correlates for each of these attributes in the nXIIts. This nucleus is 83% larger in males than in females. This is caused primarily by a sex difference in neuropil volume as there is no significant sex difference in the number of neurons in nXIIts. nXIIts grows by 34% in females given testosterone as adults. It is about 8% larger on the left than on the right in males, females, and females treated with testosterone. Sex differences are also found in the rostral (lingualis) portion of nXII, which controls muscles of the tongue, but there is no effect here of adult treatment with testosterone. Comparisons of these data with earlier measures of synaptic density and morphology in nXIIts suggest that the testosterone acts on this nucleus by inducing a modest increase in synapse numbers and by altering the efficacy of synapses in nXIIts. This contrasts with the effects of testosterone on n. robustus archistriatalis, a telencephalic component of the song system in which testosterone induces massive amounts of synaptogenesis.
舌下神经核的尾部（气管鸣管部，nXIIts）包含支配鸣禽鸣管的运动神经元。它接收来自端脑和中脑核团的投射，这些投射对于发声是必需的。其神经元聚集雄激素。本研究评估了金丝雀舌下神经核的大体形态。在这个物种中，雄性的鸣叫比雌性更频繁、更精细且更具刻板性。成年雌性通过发展出频繁鸣叫的刻板性鸣叫来对睾酮作出反应。雄性金丝雀的鸣叫受鸣唱系统左侧损伤的干扰比右侧损伤更大。我们在nXIIts中发现了与这些特征相关的解剖学关联。这个核团在雄性中比雌性大83%。这主要是由神经毡体积的性别差异导致的，因为nXIIts中的神经元数量没有显著的性别差异。成年后给予睾酮的雌性，其nXIIts增大了34%。在雄性、雌性以及接受睾酮治疗的雌性中，nXIIts左侧比右侧大约大8%。在控制舌肌的nXII的前部（舌部）也发现了性别差异，但成年后给予睾酮对此没有影响。将这些数据与nXIIts中突触密度和形态的早期测量结果进行比较表明，睾酮通过诱导突触数量适度增加以及改变nXIIts中突触的效能来作用于这个核团。这与睾酮对原纹状体粗壮核的作用形成对比，原纹状体粗壮核是鸣唱系统的一个端脑组成部分，在其中睾酮诱导大量的突触形成。
