Wild J M
Department of Anatomy, School of Medicine, University of Auckland, New Zealand.
Brain Behav Evol. 1994;44(4-5):192-209. doi: 10.1159/000113577.
A series of studies is described which in general aim to identify two sets of neural linkages in the brain and spinal cord of songbirds and non-songbirds, these avian types differing along a dimension of 'complexity of vocal communication'. One set of linkages is postulated to link the vocal system with the respiratory system, since birds, like humans, require controlled expiration in order to vocalize normally. The other set is thought to link the auditory system with the vocal system, at least in songbirds, because they are dependent upon auditory feedback for vocal learning. The systems and their linkages can be regarded as forming an 'auditory-vocal-respiratory axis', around which the animal's communication system evolves and revolves. The experimental strategy used was one which began at the periphery (the abdominal expiratory muscles), then progressively identified more central neural structures using retrograde transport methods in partial combination with recordings of single cell activity. The projections delineated by these methods were then defined in detail by anterograde tracing methods. The results of the studies confirmed the expectation that the vocal and respiratory systems have many neural elements in common. They also suggested that songbirds and non-songbirds possess similar neural pathways in the brainstem and spinal cord for the control of both vocalization and respiration but indicated that there may be significant differences between the two types of birds in the degree to which the telencephalon is able to modulate respiratory-vocal activity downstream. Thus, whereas there is a cascade of descending projections terminating upon syringeal and laryngeal motoneurons and expiratory premotor neurons in both songbirds and non-songbirds, the most rostral origin of this cascade is the telencephalic nucleus robustus archistriatalis in (male) songbirds but, apparently, the dorsomedial nucleus of the intercollicular complex of the midbrain (DM) in pigeons. Connectional studies of the auditory system in pigeons delineated a series of projections which originate in Field L2, the primary telencephalic auditory area, and leave the telencephalon via the nucleus archistriatum intermedium, pars medialis (Aivm), after traversing a minimum of three synapses within the telencephalon.(ABSTRACT TRUNCATED AT 400 WORDS)
本文描述了一系列研究，其总体目标是在鸣禽和非鸣禽的大脑和脊髓中识别出两组神经连接，这些鸟类类型在“发声交流复杂性”维度上存在差异。假设其中一组连接将发声系统与呼吸系统相连，因为鸟类与人类一样，正常发声需要控制呼气。另一组连接被认为至少在鸣禽中是将听觉系统与发声系统相连，因为它们在发声学习中依赖听觉反馈。这些系统及其连接可被视为形成了一个“听觉 - 发声 - 呼吸轴”，动物的交流系统围绕该轴进化和运转。所采用的实验策略是从外周（腹部呼气肌）开始，然后使用逆行运输方法并部分结合单细胞活动记录，逐步识别更中枢的神经结构。通过这些方法描绘出的投射随后通过顺行追踪方法进行详细定义。研究结果证实了发声和呼吸系统有许多共同神经元件的预期。研究还表明，鸣禽和非鸣禽在脑干和脊髓中具有相似的神经通路来控制发声和呼吸，但表明这两种鸟类在端脑能够调节下游呼吸 - 发声活动的程度上可能存在显著差异。因此，虽然在鸣禽和非鸣禽中都有一系列下行投射终止于鸣管和喉部运动神经元以及呼气前运动神经元，但这一投射级联的最前端起源在（雄性）鸣禽中是端脑的原纹状体粗壮核，而在鸽子中显然是中脑顶盖间复合体的背内侧核（DM）。对鸽子听觉系统的连接研究描绘了一系列投射，这些投射起源于端脑的主要听觉区域L2，在端脑内至少经过三个突触后，通过中间原纹状体核内侧部（Aivm）离开端脑。（摘要截取自400字）
