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表征外部世界以及我们如何解释或感知外部世界方面起着重要作用。例如，以英语为母语的人很容易将音节/ra/和/la/分类，而没有接触过英语的日本人很难区分这两个音节。听者是否表现出这种分类感知取决于发育过程中声刺激的分布。早期的研究表明，当言语刺激遵循双峰分布时，就会出现分类知觉；当言语刺激遵循单峰分布时，不会发生范畴知觉。适当的早期语言接触对语言能力的发展至关重要。缺乏或不适当的语言接触会导致语言学习障碍。理解发展性声音输入、听觉皮层表征和感知之间的关系对于理解语言发展非常重要，也是本研究的主要目标。我们建议用大鼠作为模型系统来研究刺激统计对皮质可塑性和知觉的作用。我们感兴趣的是声学刺激的统计数据如何导致听觉皮层表征的变化，以及这些变化如何成为分类感知的基础。特别是，该项目将测试以下假设：1)时间重复率影响单音环境中的频谱可塑性，2)双音环境中的统计依赖性决定了声音的表现方式，以及3)声音的分类感知只有在它们的表现是统计独立的情况下才会发生。大鼠幼仔在发育过程中将在特定的声学环境中饲养。为了测量皮层表征，这些动物的初级听觉皮层将被电生理映射。将测试声音辨别和识别，以评估这些大鼠对音调频率的分类感知。相关性描述：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。在不适当的语言输入环境中长大的人可能会患上交流障碍。本研究旨在了解声音环境、大脑声音表征和感知之间的关系。

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.