Neurophysiology of Multisensory Integration

描述(申请人提供)：不同的感官采样物理对象的独特方面，应该为大脑提供关于对象的更丰富的描述，以及关于它们的位置、身份和运动的汇聚证据。虽然对猫上丘的多感觉处理有了详细的解释，在非人类灵长类动物中也有一些多感觉脑区的详细说明，但我们对不同感觉系统的信息在人类新皮质中是如何结合的只有一个初步的了解。这项建议的目的是通过结合使用事件相关电位(ERP)记录和功能成像(FMRI)来加深我们对人类皮质多感觉整合的理解。对128个头皮电极记录的ERP进行高密度映射，将这些映射与单个受试者MRI衍生的解剖学共同配准，并对表面记录的数据进行来源分析，将使我们能够评估参与此类整合的大脑区域。平行的功能磁共振实验将使我们能够精确地定义给定的多感觉操作所涉及的大脑区域。ERP源分析和fMRI数据的整合将提供多感官整合的时空动力学。关键是，事件相关电位的精确时间分辨率将使我们能够评估多感觉整合效应的时间进程相对于正在进行的单感觉加工的时间进程。我们建议确定：1)双感觉视听刺激的单感觉成分之间的时间分离参数导致与双感觉刺激相关的ERP交互的修改；2)双感觉刺激的空间分离是否改变与双感觉刺激相关的早期ERP交互；3)自上而下的影响(注意)是否能影响最早的多感觉交互到双感觉刺激；4)评估在完全与任务无关的感觉通道(视觉)中同时刺激对与第二个任务相关的感觉通道(躯体)的ERP交互的影响。具体地说，我们希望评估当不相关的通道与任务相关的空间信息相矛盾或确认时的效果；5)由同时呈现的听觉刺激引起的视觉表观运动知觉的虚幻变化是否是听觉驱动的视觉运动加工区域加工变化的结果。通过这些研究，我们将开始探索“绑定”过程的神经机制，即跨不同感觉通道的相关输入。

DESCRIPTION (provided by applicant): That the different senses sample unique aspects of physical objects should provide the brain with both a richer description of objects, and converging evidence concerning their position, identity and movement. Although there has been a detailed explication of multi sensory processing in the superior colliculus of cats and a number of multi sensory brain regions have been detailed in non-human primates, we have only a rudimentary understanding of how information from different sensory systems is combined in the human neo-cortex. The purpose of this proposal is to further our understanding of human cortical multi sensory integration through the combined use of event-related potential (ERP) recordings and functional imaging (fMRI). High-density mapping of ERPs recorded from 128 scalp electrodes, co-registration of these maps with individual subject MRI-derived anatomy, and source analysis of the surface recorded data will allow us to assess the brain regions involved in such integrations. Parallel fMRI experiments will allow us to precisely define the brain regions involved in a given multi sensory operation. Integration of ERP source-analyses and fMRI data will provide the spatio-temporal dynamics of multi sensory integration. Critically, the precise temporal resolution of the ERP will allow us to assess the time-course of multi sensory integration effects relative to the time-course of ongoing unisensory processing. We propose to determine: 1) the temporal separation parameters between the unisensory constituents of a bi-sensory audio-visual stimulus that result in modifications of the ERP interactions associated with bi-sensory stimulation, 2) whether spatial separation of bi-sensory stimuli modifies the early ERP interactions associated with bi-sensory stimulation, 3) whether top-down influences (attention) can effect the earliest multi-sensory interactions to bi-sensory stimulation, 4) to assess the effects of simultaneous stimulation in an entirely task-irrelevant sensory modality (vision) upon the ERP interactions with a second task-relevant sensory modality (somesthesis). Specifically, we wish to assess the effects of the irrelevant modality when it either contradicts or confirms task-relevant spatial information, 5) whether illusory changes in the perception of visual apparent motion, which are induced by presentation of simultaneous auditory stimuli, are the result of auditorily driven processing changes in visual motion processing areas. Through these studies, we will begin to explore the neural mechanisms underlying the process of "binding," related inputs across the separate sensory modalities.