Temporal and Spatial Processing in the Lateral Belt of Auditory Cortex

 描述(申请人提供)：处理复杂声音的能力对于识别和定位大多数真实世界的对象和事件、理解语音以及制作和欣赏音乐至关重要。有听力障碍的人可能会被这种功能障碍摧毁，这可能会让他们在社会上孤立、抑郁，甚至自杀。某些形式的听力障碍是听觉外周问题的结果，在这种情况下，助听器和人工耳蜗可能是有益的。然而，这些干预措施对那些由于中风、脑损伤，特别是自然衰老等中央原因导致的听力障碍的人来说，效果有限(如果有的话)。不幸的是，目前还没有既定的补救疗法或治疗方法来治疗由中枢功能障碍引起的听力障碍。同样，对听觉刺激的注意对这些特征的感知至关重要，尽管我们对这些注意影响的神经机制同样知之甚少。更好地了解作为听觉感知和选择性听觉注意基础的正常皮质过程，对于开发有效的中枢调节听力障碍治疗方法是必要的。先前的研究表明，灵长类听觉皮质独立地处理空间和非空间(时间)信息。具体地说，人们认为在横向带中 听觉皮层，前外侧场(AL)处理时间信息，尾侧场(CL)处理空间信息，中外侧场(ML)以中间方式处理这两个特征。然而，到目前为止，还没有直接证据表明侧带神经元的活动与对时间或空间声学特征的感知有关。在拟议的研究中，我们将记录侧带中单个神经元的活动，而非人类受试者关注并主动区分相同声刺激的时间或空间特征。我们将使用基于特征的注意的心理物理任务，以确定自上而下的注意如何影响被认为处理不同声学特征的皮质神经元的活动，以及受试者对这些特征的感知。这些结果将为长期持有的灵长类听觉皮质由至少两个平行处理流组成的假设提供第一个在单个神经水平上的直接测试。他们还将首次研究自上而下的注意力如何在单个神经元水平上影响听觉皮质中的神经元活动。这些实验将区分两个相互竞争的假设：注意效应是否在整个听觉皮质区域是全局的，无论哪个声学特征被注意到，还是注意效应只对那些处理被注意声学特征的神经元有选择性。最后，这些结果还将提供第一个测试，测试注意机制是否在 听觉系统符合目前自上而下的注意力对单个神经元活动的影响框架，这在很大程度上是基于对视觉皮质的大量研究。

 DESCRIPTION (provided by applicant): The ability to process complex sounds is critical for identifying and localizing most real-world objects and events, understanding speech, and producing and appreciating music. Individuals with hearing deficits can be devastated by this dysfunction which can leave them socially isolated, depressed, and even suicidal. Some forms of hearing deficits are the result of problems in the auditory periphery, in which case hearing aids and cochlear implants can be beneficial. However, these interventions have limited if any effect for those with hearing deficits due to central causes, such as strokes, brain injury, and especially natural aging. Unfortunately there are currently no established remedial therapies or treatments for hearing deficits that are caused by central dysfunction. Similarly, attention to auditory stimuli is critical for the perception of those features, although we again have very litte understanding of the neural mechanisms of these attentional influences. A better understanding of the normal cortical processes that underlie auditory perception and selective auditory attention is necessary to develop effective treatments for centrally-mediated hearing deficits. Previous research has indicated that the primate auditory cortex processes spatial and non-spatial (temporal) information independently. Specifically, it is believed that in the lateral belt auditory cortex, the anterolateral field (AL) processes temporal information while the caudolateral field (CL) processes spatial information, with the middle-lateral field (ML) processing both features in an intermediate way. To date, however, there has been no direct evidence that the activity of neurons in the lateral belt is correlated with the perception of temporal or spatial acoustic features. In the proposed study we will record single neuron activity in the lateral belt while non-human subjects attend to and actively discriminate the temporal or spatial features of identical acoustic stimuli. We will use psychophysical tasks that will engage feature-based attention in order to determine how top-down attention influences the activity of cortical neurons believed to be processing the different acoustic features, and the subject's perception of those features. These results will provide the first direct test, at the single neuro level, of the long- held hypothesis that the primate auditory cortex is composed of at least two parallel processing streams. They will also provide the first investigation of how top-down attention influences neuronal activity in the auditory cortex at the single neuron level. These experiments will distinguish between two competing hypotheses: whether attentional effects are global across auditory cortical areas regardless of which acoustic feature is being attended vs the attentional effects are selective to only those neurons processing the attended acoustic feature. Finally, these results will also provide the first test of whether attention mechanisms in the auditory system fit into the current framework of top- down attentional influences on single neuron activity that are largely based on a plethora of studies in the visual cortex.