SPEECH AND LANGUAGE PROCESSING IN APHASIA

本研究的主要目的是通过研究失语症患者的言语和语言处理缺陷来识别和描述言语和理解的过程和机制以及神经基质。研究的重点是语音结构和词汇，以及语音到意义和意义到语音的加工阶段。关于将声音映射到意义的加工阶段，假设失语患者的缺陷源于声音结构在词汇中引发激活的程度。这类障碍的两个潜在来源将被研究，一个侧重于词汇本身的激活模式，另一个侧重于从声音结构到词汇形式的映射。词汇竞争对词汇加工的影响将通过探索语音类别“好”及其对词汇竞争对手激活的影响，词汇密度和频率对词汇决策潜伏期的影响，以及韵律和队列对口语单词识别时间过程的影响来研究。通过探索声音输入的各种变化对词汇获取的影响，包括声音失真和索引特征（如音调和说话者）的影响，来研究声音结构到词汇的映射。将使用各种方法，包括词汇决策，语义启动，辨别和眼动追踪。关于言语产生的过程和机制，我们假设包括布罗卡失语症在内的前路失语症的言语输出缺陷是其发音执行的基础障碍。为了进一步描绘出这种损伤的本质，我们将测试三个假设：有人提出，缺陷将出现在那些需要在短时间内复杂整合发音运动的音段的生产中。发音方式的产生，包括顿音、闪音、摩擦音和滑音，将被调查；2. 有人提出，协同发音的缺陷将出现在更大更复杂的语言语境中，特别是跨词边界。探讨元音协同发音对前辅音和辅音发音对前元音的影响；3. 有人提出，由前失语症产生的音位错，即语音替换错误，有语音或发音基础。在所有这些生产研究中，声学分析都是对前、后失语症患者的言语生产进行的，以推断产生声学模式的发音状态。

The broad goals of this research are to identify and delineate the processes and mechanisms and the neural substrates underlying speaking and understanding by investigating speech and language processing deficits in aphasic patients. The major focus of research is on sound structure and the lexicon and the processing stages that map sound to meaning and meaning to sound. With respect to the processing stages that map sound to meaning, it is hypothesized that the deficits of aphasic patients stem from the extent to which sound structure elicits activation in the lexicon. Two potential sources of such impairment will be investigate, one focusing on activation patterns within the lexicon itself and the other on the mapping from sound structure to lexical form. The influence of lexical competition on lexical processing will be investigated by exploring the effects of phonetic category 'goodness' and its influence on the activation of its lexical competitor, the effects of lexical density and frequency on lexical decision latencies, and rhyme and cohort effects on the time course of spoken word recognition. The mapping from sound structure to the lexicon will be investigated by exploring the influence of various changes to the acoustic input on lexical access including the influence of acoustic distortion and indexical features such as voice pitch and speaker. Various methods will be used including lexical decision, semantic priming, discrimination, and eye tracking. With respect to the processes and mechanisms contributing to speech production, it is hypothesized that the speech output deficits of anterior aphasics including Broca's aphasics have as their basis impairments in articulatory implementation. To further map out the nature of this impairment, three hypotheses will be tested: 1. It is proposed that deficits will emerge in the production of those sound segments that require the complex integration of articulatory movements over short periods of time. The production of manner of articulation including stops, affricates, fricatives, and glides will be investigated; 2. It is proposed that deficits in coarticulation will emerge in larger and more complex linguistic contexts, specifically across word boundaries. The influence of vowel coarticulation on a preceding consonant and consonant articulation on a preceding vowel will be explored; 3. It isproposed that phonemic paraphasias, i.e. sound substitutionerrors, produced by anterior aphasics have a phonetic orarticulatory basis. In all of these production studies,acoustic analyses are conducted of speech productions ofboth anterior and posterior aphasic patients to infer thearticulatory states giving rise to the acoustic patterns.