Ashmore Robin C, Renk Jessica A, Schmidt Marc F
Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Neurosci. 2008 Mar 5;28(10):2613-23. doi: 10.1523/JNEUROSCI.4547-07.2008.
Brainstem motor structures send output commands to the periphery and are dynamically modulated by telencephalic inputs. Little is known, however, about ascending brainstem control of forebrain motor structures. Here, we provide the first evidence for bottom-up activation of forebrain motor centers by the respiratory brainstem. We show that, in the avian vocal control system, activation of the brainstem inspiratory nucleus paraambigualus (PAm), a likely homolog of the mammalian rostral ventral respiratory group, can drive neural activity bilaterally in the forebrain vocal control nuclei HVC (used as a proper name) and the robust nucleus of the arcopallium (RA). Furthermore, this activation is abolished by lesions of nucleus uvaeformis (Uva), a thalamic nucleus necessary for song production. We identify a type of bursting neuron within PAm whose activity is correlated, in an Uva dependent manner, to bursting activity in RA, rather than to the respiratory rhythm, and is robustly active during the production of stimulus evoked vocalizations. Because this ascending input results in cross-hemisphere activation, our results suggest a crucial role for the respiratory brainstem in coordinating forebrain motor centers during vocal production.
脑干运动结构向周围发送输出指令，并受到端脑输入的动态调节。然而，关于脑干对前脑运动结构的上行控制，我们却知之甚少。在此，我们首次提供了呼吸脑干对前脑运动中枢进行自下而上激活的证据。我们发现，在鸟类发声控制系统中，脑干吸气核旁疑核（PAm）（可能是哺乳动物 Rostral 腹侧呼吸组的同源物）的激活能够双侧驱动前脑发声控制核团 HVC（用作专有名称）和弓状皮质粗核（RA）的神经活动。此外，丘脑核团卵圆核（Uva）（发声所必需的丘脑核）的损伤会消除这种激活。我们在 PAm 内鉴定出一种爆发性神经元，其活动以 Uva 依赖的方式与 RA 中的爆发性活动相关，而不是与呼吸节律相关，并且在诱发发声产生期间强烈活跃。由于这种上行输入导致跨半球激活，我们的结果表明呼吸脑干在发声产生过程中协调前脑运动中枢方面起着关键作用。
