Coleman Melissa J, Roy Arani, Wild J Martin, Mooney Richard
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Neurosci. 2007 Sep 12;27(37):10024-36. doi: 10.1523/JNEUROSCI.2215-07.2007.
In songbirds, nucleus Uvaeformis (Uva) is the sole thalamic input to the telencephalic nucleus HVC (used as a proper name), a sensorimotor structure essential to learned song production that also exhibits state-dependent responses to auditory presentation of the bird's own song (BOS). The role of Uva in influencing HVC auditory activity is unknown. Using in vivo extracellular and intracellular recordings in urethane-anesthetized zebra finches, we characterized the auditory properties of Uva and examined its influence on auditory activity in HVC and in the telencephalic nucleus interface (NIf), the main auditory afferent of HVC and a corecipient of Uva input. We found robust auditory activity in Uva and determined that Uva is innervated by the ventral nucleus of lateral lemniscus, an auditory brainstem component. Thus, Uva provides a direct linkage between the auditory brainstem and HVC. Although low-frequency electrical stimulation in Uva elicited short-latency depolarizing postsynaptic potentials in HVC neurons, reversibly silencing Uva exerted little effect on BOS-evoked activity in HVC neurons. However, high-frequency stimulation in Uva suppressed auditory-evoked synaptic and suprathreshold activity in all HVC neuron types, a process accompanied by decreased input resistance of individual HVC neurons. Furthermore, high-frequency stimulation in Uva simultaneously suppressed auditory activity in HVC and NIf. These results suggest that Uva can gate auditory responses in HVC through a mechanism that involves inhibition local to HVC as well as withdrawal of auditory-evoked excitatory drive from NIf. Thus, Uva could play an important role in state-dependent gating of auditory activity in telencephalic sensorimotor structures important to learned vocal control.
在鸣禽中，葡萄状核（Uva）是端脑核团HVC（用作专有名称）的唯一丘脑输入，HVC是学习鸣叫产生所必需的感觉运动结构，对鸟类自身鸣叫（BOS）的听觉呈现也表现出状态依赖性反应。Uva在影响HVC听觉活动中的作用尚不清楚。我们在氨基甲酸乙酯麻醉的斑马雀中使用体内细胞外和细胞内记录，表征了Uva的听觉特性，并研究了其对HVC和端脑核团界面（NIf）听觉活动的影响，NIf是HVC的主要听觉传入神经，也是Uva输入的共同接受者。我们在Uva中发现了强烈的听觉活动，并确定Uva由外侧丘系腹侧核（听觉脑干的一个组成部分）支配。因此，Uva在听觉脑干和HVC之间提供了直接联系。虽然在Uva中进行低频电刺激会在HVC神经元中引发短潜伏期的去极化突触后电位，但可逆性地沉默Uva对HVC神经元中BOS诱发的活动影响很小。然而，在Uva中进行高频刺激会抑制所有HVC神经元类型的听觉诱发突触和阈上活动，这一过程伴随着单个HVC神经元输入电阻的降低。此外，在Uva中进行高频刺激同时抑制了HVC和NIf中的听觉活动。这些结果表明，Uva可以通过一种机制来调节HVC中的听觉反应，该机制涉及HVC局部的抑制以及从NIf撤回听觉诱发的兴奋性驱动。因此，Uva可能在对学习发声控制很重要的端脑感觉运动结构中听觉活动的状态依赖性调节中发挥重要作用。
