Auditory Processing and Memory for Complex Signals

描述(申请人提供)：口语在交流中的力量是人类物种的决定性适应能力之一，它依赖于语音信号的快速产生和感知。鸣禽是少数几种动物中最容易研究的，它们学会了像人类一样产生用于社会交流的声音信号。在鸣禽中，我们对斑马雀的了解是最先进的。这项应用提出利用鸣禽前脑中听觉神经元的特性来研究为听觉通信信号的识别和记忆服务的基本神经过程。年轻的雄性斑马雀通过模仿人类语音习得的过程，从成年导师那里学习发声。这些发声在成年后变得刻板印象，每个人都是独一无二的，为定量研究服务于这一自然交流系统的大脑过程提供了丰富的材料。利用前脑听觉区域--尾状内侧黑质(NCM)的神经生理学记录，P.I.展示了一种神经元形式的识别记忆，这种记忆对同种声音的持续时间比对异种声音的持续时间更长。这些持久的记忆区分不同个体同种的独特发声，表明NCM在处理声音信号方面发挥着特殊的作用。可以评估区分NCM神经元声音的显著声学和时间特征，因为在这种准备过程中，重复呈现新的声音会导致感觉反应的快速、可量化的下降。当出现不同的声音时，响应返回到其初始高电平。这是一种刺激特异性适应的形式，让人想起哺乳动物听觉皮质所描述的类似过程。P.I.现在建议用先进的生理学方法，包括急性和慢性多电极记录，从NCM记录觉醒的斑马雀，以确定1)伴随着特定声音信号记忆的神经反应模式的详细变化；2)支配由音节序列组成的更复杂声音的神经处理的时间规则，就像在歌曲中发生的那样；以及3)这种听觉识别和记忆系统在与同种声音的实时互动中的参与方式。这些结果不仅将为鸣禽行为相关信号的听觉处理提供定量描述，还将揭示将快速声音序列与可识别的听觉对象联系起来的神经过程。这是解码语音和歌曲的基本步骤，因此这些研究可能为人类正常和病理性的语音处理提供有用的模型。

DESCRIPTION (provided by applicant): The power of spoken language in communication is one of the defining adaptations of the human species, and it depends on the rapid production and perception of speech signals. Songbirds are the most easily studied of the few animal taxa that learn to produce vocal signals for social communication as humans do. Among songbirds, our knowledge of the zebra finch is most advanced. This application proposes to use the properties of auditory neurons in the songbird forebrain to investigate basic neural processes that serve discrimination and memory for auditory communication signals. Young male zebra finches learn their vocalizations from adult tutors through a process of imitation that resembles human speech acquisition. These vocalizations become stereotyped in adulthood and are unique to each individual, providing rich material for quantitative study of the brain processes that serve this natural communication system. Using neurophysiological recording in a forebrain auditory area, the caudo-medial nidopallium (NCM), the P.I. has demonstrated a neuronal form of recognition memory that lasts longer for conspecific than for heterospecific vocal sounds. These long-lasting memories discriminate the unique vocalizations of individual conspecifics, suggesting that NCM plays a special role in processing vocal signals. The significant acoustic and temporal features that distinguish sounds for NCM neurons can be assessed because, in this preparation, repeated presentation of a novel sound results in rapid, quantifiable decreases of the sensory response. When a different sound is presented, the response returns to its initial high level. This is a form of stimulus specific adaptation, reminiscent of similar processes described for the mammalian auditory cortex. The P.I. now proposes to record from NCM in awake zebra finches with advanced physiological methods, including acute and chronic multi-electrode recording, to determine 1) the detailed changes in neural response pattern that accompany memorization of a specific sound signal; 2) the temporal rules that govern the neural processing of more complex sounds composed of syllable sequences, as occurs in song; and 3) the way in which this auditory recognition and memory system is engaged during real-time interaction with conspecifics. The results will not only provide a quantitative description of auditory processing for behaviorally relevant signals in songbirds, but will also shed light on neural processes that link rapid sound sequences into recognizable auditory objects. This is a basic step in decoding speech, as well as song, so these studies may provide useful models for normal and pathological speech processing in humans.