The role of stimulus statistics on cortical plasticity and categorical perception

描述(由申请人提供)：早期经验在塑造我们的大脑如何代表外部世界以及我们如何解释或感知外部世界方面扮演着重要的角色。例如，尽管以英语为母语的人很容易将音节/ra/和/la/归类，但没有接触英语的日语人很难区分这两个音节。听者是否表现出这种直截了当的知觉，取决于发展过程中听觉刺激的分布。早期的研究表明，当言语刺激服从双峰分布时，就会产生范畴知觉；当言语刺激服从单峰分布时，就不会产生范畴知觉。适当的早期语言接触对语言能力的发展至关重要。贫困或不当的语言接触会导致语言学习障碍。理解发育性声学输入、听觉皮质表征和知觉之间的关系对于理解语言发展很重要，这也是本研究的主要目标。我们建议使用大鼠作为一个模型系统来研究刺激统计对皮质可塑性和知觉的作用。我们感兴趣的是，声音刺激的统计数据如何导致听觉皮质表征的变化，以及这些变化如何奠定分类知觉的基础。特别是，本项目将检验以下假设：1)时间重复率影响单音环境中的频谱可塑性；2)双音环境中的统计相关性决定声音如何被呈现；以及3)只有当声音的呈现在统计上独立时，才会发生对声音的范畴知觉。幼鼠将在发育过程中在特定的声学环境中饲养。为了测量皮质表征，这些动物的初级听觉皮质将被电生理标测。将进行声音辨别和识别测试，以评估这些大鼠对音调频率的分类感知。相关描述：语言技能在人类中被认为是独一无二的，我们有效沟通的能力取决于我们的语言天赋。在语音输入不当的情况下长大的人可能会患上沟通障碍。这项研究旨在了解声环境、大脑对声音的表征和知觉之间的关系。

DESCRIPTION (provided by applicant): Early experience plays an important role in shaping both how our brains represent the external world and how we interpret or perceive it. For example, while native English speakers readily categorize the syllables /ra/ and /la/, Japanese speakers with no exposure to English have difficulty distinguishing these two syllables. Whether or not listeners show such categorical perception can depend on the distribution of acoustical stimuli during development. Earlier studies have shown that when speech stimuli follow a bimodal distribution, categorical perception occurs; when speech stimuli follow a unimodal distribution, categorical perception does not occur. Proper early language exposure is critical to the development of language ability. Impoverished or improper language exposure can lead to language learning impairments. Understanding the relationship between developmental acoustic inputs, auditory cortex representations and perception is important in understanding language development and is the main goal of this proposal. We propose using the rat as a model system to study the role of stimulus statistics on cortical plasticity and perception. We are interested in how the statistics of acoustical stimuli can lead to changes in auditory cortex representations and how these changes could underlie categorical perception. In particular, this project will test the following hypotheses: 1) temporal repetition rates influence spectral plasticity in a single- tone environment, 2) statistical dependence in a two-tone environment determines how sounds are represented, and 3) categorical perception of sounds will occur only if their presentations is statistically independent. Rat pups will be reared in specific acoustic environments during development. To measure cortical representations, the primary auditory cortices of these animals will be mapped electrophysiologically. Sound discrimination and identification will be tested to assess categorical perception of tonal frequencies in these rats. Description of Relevance: Language skill is considered unique among humans, and our ability to communicate efficiently and effectively hinges on our language aptitude. Individuals who grow up with improper speech input can develop communication disorders. This research aims to understand the relationship between the acoustical environment, brain representation of sound, and perception.