Neural Mechanisms of Auditory Attention

描述（由申请人提供）：感官信息不断涌入我们的感知系统。成功地选择性地关注特定的环境刺激需要我们忽略竞争的刺激。本项目探讨了竞争听觉干扰的感知加工的大脑机制。认知科学长期以来一直在争论不相关的刺激被加工的程度，自20世纪50年代以来，理论家们主张要么是早期选择（在感觉层面上的门控导致对干扰物的加工有限），要么是后期选择（在对干扰物进行完整的感觉加工后在意识层面上的门控）。这两种观点在最近的一个模型中得到了调和（Lavie, 1995,2000; Lavie et al., 2004），该模型根据注意任务所要求的负荷水平（高、低）和心理加工（知觉、认知控制）来确定选择位点。根据这种“负荷”模型，在高知觉负荷或低认知控制负荷的条件下，成功的选择注意是最好的。相当多的行为证据和一些神经影像学数据支持负荷模型，至少在视觉模式上。听觉模态的相关研究很少，主要涉及行为和电生理测量。我们拟利用erp和fMRI的同时记录，研究知觉负荷和认知控制负荷（即工作记忆）如何影响与任务无关的语音在听觉通路上的知觉加工。语音是一种理想的干扰选择，因为它们与人类高度相关，并且它们的处理已经相对较好地定位于大脑。此外，将采用复杂的声学匹配的非语音来测试选择性注意效应对音位感知的特异性。我们建议提供直接的神经证据，以支持听觉模态的早期和晚期选择观点之间的争论。具体目的1是研究皮层听觉系统中不相关语音的加工在多大程度上受到初级任务的感知需求的调节。根据负荷模型，我们假设在高知觉负荷条件下，言语相关区域的大脑活动减少，与分心物相关的ERP反应较小。具体目的2是研究皮层听觉系统中不相关语音的加工在多大程度上受到主要任务所要求的认知控制的调节。根据负荷模型，我们假设在低工作记忆负荷条件下，言语相关区域的大脑活动减少，与分心相关的ERP反应较小。这个项目将提供一些关于健康人类听觉系统选择性注意的皮层机制的第一个神经影像学证据。研究结果为选择性注意的负荷模型提供了一个相对明确的检验。

DESCRIPTION (provided by applicant): Sensory information continuously floods our perceptual systems. Success at attending selectively to a particular environmental stimulus requires us to ignore competing stimuli. This project examines the brain mechanisms that underlie perceptual processing of competing auditory distractors. Cognitive science has long debated the extent to which irrelevant stimuli are processed, with theorists since the 1950s advocating either early selection (gating at the sensory level leading to limited processing of distractors) or late selection (gating at the awareness level after complete sensory processing of distractors). The two views are reconciled in a recent model (Lavie, 1995, 2000; Lavie et al., 2004) that determines the locus of selection according to the load level (high, low) and the mental processing (perceptual, cognitive control) demanded by the attention task. According to this "load" model, successful selective attention is best achieved under conditions of high perceptual load or low cognitive control load. Considerable behavioral evidence and some neuroimaging data lend support to the load model, at least in the visual modality. Corresponding studies in the auditory modality are scarce and involve mainly behavioral and electrophysiological measures. We propose to investigate, using simultaneous recordings of ERPs and fMRI, how perceptual load and cognitive control load (i.e., working memory) each influence the perceptual processing of task-irrelevant speech sounds along the auditory pathway. Speech sounds are an ideal choice as distractors because they are highly relevant to humans, and their processing has been relatively well localized in the brain. In addition, complex acoustically-matched non- speech sounds will be employed to test the specificity of selective attention effects to phonemic perception. We propose to provide direct neural evidence bearing on the debate between early and late selection views in the auditory modality. Specific Aim 1 is to study the extent to which the processing of irrelevant speech sounds in the cortical auditory system is modulated by the perceptual demands of a primary task. In accordance with the load model, we hypothesize a reduction in brain activity in speech-related areas and smaller distractor-related ERP responses under conditions of high perceptual load. Specific Aim 2 is to study the extent to which the processing of irrelevant speech sounds in the cortical auditory system is modulated by the cognitive control demanded by the primary task. In accordance with the load model, we hypothesize a reduction in brain activity in speech-related areas and smaller distractor-related ERP responses under conditions of low working memory load. This project will provide some of the first neuroimaging evidence concerning cortical mechanisms of selective attention in the healthy human auditory system. The results should provide a relatively unambiguous test of the load model of selective attention. Project Narrative: In addition to more clearly delineating the neuroanatomic foundations of our auditory perceptual and attention system, the findings will help identify and decipher the processing deficits that underlie auditory attention impairments in schizophrenia and dyslexia, which will be invaluable for formulating effective approaches to remediation in these conditions.