Neural Mechanisms of Auditory Attention

描述(申请人提供)：感官信息不断涌入我们的感知系统。要想成功地选择性地关注某个特定的环境刺激，我们需要忽略相互竞争的刺激。这个项目考察了相互竞争的听觉干扰物的知觉处理所依据的大脑机制。长期以来，认知科学一直在争论无关刺激被处理的程度，自20世纪50年代以来，理论家们主张要么早期选择(在感觉水平上进行选通，导致对干扰物的处理有限)，要么主张晚选择(在干扰物完成感觉处理后，在意识水平上进行选通)。这两种观点在最近的一个模型(Lavie，1995,2000；Lavie et al.，2004)中是一致的，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)来确定选择地点。根据这一“负荷”模型，在高知觉负荷或低认知控制负荷的条件下，成功的选择性注意效果最佳。相当多的行为证据和一些神经成像数据支持负荷模型，至少在视觉形态上是这样。在听觉通道方面的相应研究很少，主要涉及行为和电生理测量。我们建议使用ERPs和fMRI的同时记录来研究知觉负荷和认知控制负荷(即工作记忆)如何影响听觉通路上与任务无关的语音的知觉加工。语音是分散注意力的理想选择，因为它们与人类高度相关，而且它们的处理在大脑中相对较好地进行了定位。此外，还将使用复杂的声学匹配的非语音来测试选择性注意效应对音素知觉的专一性。我们建议提供直接的神经证据，与听觉通道中早期和晚期选择观点之间的争论有关。具体目标1是研究大脑皮质听觉系统中对无关语音的处理在多大程度上受到主要任务的知觉需求的调节。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，分心相关的ERP反应较小。具体目标2是研究大脑皮层听觉系统中不相关语音的处理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的条件下，言语相关区域的大脑活动减少，分心相关的ERP反应较小。该项目将提供一些关于健康人类听觉系统中选择性注意的皮质机制的第一批神经成像证据。这一结果应该为选择性注意的负荷模型提供一个相对明确的测试。 项目描述：除了更清楚地描绘我们的听觉感知和注意系统的神经解剖学基础外，这些发现还将有助于识别和破译精神分裂症和阅读障碍患者听觉注意障碍背后的处理缺陷，这对于制定有效的补救方法将是非常宝贵的。

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.