The neural basis for birdsong rhythm and sequencing

描述(申请人提供)：鸟鸣是一种习得的、复杂的行为，它在多个时间尺度上组织起来，类似于人类语音的各个方面，如韵律和音素。有人提出，歌曲只在一个精细的时间尺度上通过神经回路进行编码；然而，这些研究仅限于前脑的前馈控制。这项研究的总体目的是研究反复出现的脑干-前脑回路(BFC)如何在更广泛的范围内代表斑雀鸣叫的节奏方面。我假设，BFC将前脑活动的必然放电与为即将到来的发声产生命令相结合。我将用成人歌曲制作过程中BFC两个关键区域的长期单一单位录音来验证这一假设。首先，我将从前脑核RA的背侧区域进行记录，目前人们认为它编码了伴随歌曲的呼吸活动。其次，我将从脑干核团Pam和Dm记录，这两个核团都接受背侧RA的输入，并通过丘脑投射回前脑；目前对这些亚群上的歌曲是如何编码的知之甚少。我会用音节的起始点、偏移量和长度来比较每一个区域的尖峰时序。重要的是，在这项分析中，我将利用歌曲计时和排序中的试验到试验的可变性作为一个关键的自由度：尽管斑马雀的鸣叫是高度刻板的，但它在计时和排序方面也表现出微妙而系统的变化，这可能与运动代码直接相关。像这样自然发生的扰动可能会暴露出神经网络中特别薄弱的环节，而在疾病等更严重的情况下，这些环节更容易中断。人类语言中类似的时间尺度已经被发现，并与诸如口吃和小脑等关键区域的损害等失语症有关。因此，斑马雀鸣叫中“歌曲韵律”是如何编码的这一发现，可能会揭示人类言语和已知病理的生理学基础。公开声明：BirdSong为研究大脑如何产生复杂的声音交流提供了一个令人兴奋的机会。歌曲有一种非常类似于人类语音的时间组织，但到目前为止，这种组织的神经基础仍然知之甚少。目前的研究旨在研究神经回路如何对歌曲中个别发声的节奏和顺序进行编码。因此，这项研究可能会揭示出对影响人类语音相似因素的障碍的重要见解，例如口吃。

DESCRIPTION (provided by applicant): Birdsong is a learned, complex behavior that is organized on multiple timescales that are analogous with aspects of human speech such as prosody and phonemes. It has been proposed that songs are encoded over neural circuits on a single fine timescale only; however, these studies have been restricted to feed forward control in the forebrain. The general aim of this research is to examine how recurrent brainstem-forebrain circuitry (BFC) represents the rhythmic aspects zebra finch song on broader scales. I hypothesize that BFC integrates corollary discharge of forebrain activity with the generation of commands for upcoming vocalizations. I will test this hypothesis with chronic, single-unit recordings in two key areas of BFC during adult song production. First, I will record from the dorsal region of forebrain nucleus RA, which is currently understood to encode the respiratory activity which accompanies song. Second, I will record from brainstem nuclei PAm and DM, both of which receive inputs from dorsal RA and project back towards the forebrain via the thalamus; currently very little is known about how song is encoded over these subpopulations. I will compare the timing of spike trains in each of these areas with syllable onsets, offsets and lengths. Importantly, I will exploit trial-to-trial variability in song timing and sequencing as a critical degree of freedom in this analysis: although zebra finch song is highly stereotyped, it also exhibits subtle but systematic variability in timing and sequencing that may be directly related to the motor code. Naturally occurring perturbations such as these could reveal especially weak links in neural networks that are more easily disrupted under more severe conditions such as a disease. Analogous timescales in human speech have been identified and are implicated in aphasias such as stuttering and lesions to key areas such as the cerebellum. Thus, the discovery of how "song prosody" is encoded in zebra finch song may reveal important insights into the physiological basis for human speech and known pathologies. Public statement: Birdsong has provided a exciting opportunity to investigate how the brain produces complex, vocal communication. Songs have a temporal organization that is very similar to human speech, but so far the neural basis of this organization remains poorly understood. The current study is aimed at how neural circuits encode the rhythm and order of individual vocalizations in song. This research may thus reveal important insights into disorders that affect similar elements of human speech, such as stuttering.