Auditory Information Processing in the Midbrain: Modulation by the Amygdala

描述(申请人提供)：这项研究的长期目标是了解大脑中枢如何修改对复杂声音的分析，以确定听觉和其他感官输入的情感意义。这项拟议的研究将研究一种新描述的从杏仁核到下丘(IC)的直接路径，杏仁核是调节情绪表达的前脑中心，下丘是上升听觉系统的中脑整合中心。杏仁核-丘脑的直接投射可能在相对较低水平的上行听觉通路上将情绪内容强加给听觉处理。此外，这一投射可以介导听觉皮质激活的效应，这些效应被归因于直接的皮质-丘脑通路。我们假设杏仁丘投射基于情绪状态和/或最近感觉输入的情绪意义来调节IC中声音信息处理的综合特征。该项目将研究杏仁核如何改变长胡子蝙蝠IC中的综合听觉反应，其中综合听觉反应(称为组合敏感)分析社会和声纳发声。这些反应在IC和听性脑干中的功能组织和起源已被很好地理解。连接证据表明杏仁丘投射神经元接触组合敏感的IC神经元。在拟议研究的目标1中，我们将检测杏仁基底外侧核中单个神经元或小神经元簇对简单声信号以及社会和声纳发声的反应。研究结果将确定杏仁核-丘脑通路活跃的声学条件，并发展出识别杏仁核-丘神经元的生理“信号”。目的#2将使用顺行和逆行追踪来检查杏仁丘投射的组织和联系杏仁核、听皮质和IC的环路。目的#3将使用多通道记录方法，研究杏仁核的化学和电刺激如何影响IC中简单声音信号和复杂发声的声音信息处理。目的#4将使用非侵入性皮质降温方法测试杏仁核是否主要通过其直接通路或通过其与听觉皮质-丘脑神经元的联系来影响IC神经元。相关性：这些研究将更好地理解我们对包括语音在内的声音信号的处理是如何被充满情绪的声音或我们的情绪状态所改变的。它们可能会加深我们对杏仁核在听觉学习中的作用的理解。这项工作还可能提高我们对情绪中心在耳鸣等异常听觉感知中的作用的理解。

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how analyses of complex sounds are modified by brain centers that establish the emotional significance of auditory and other sensory input. The proposed research will examine a newly described direct pathway from the amygdala, a forebrain center mediating emotional expression, to the inferior colliculus (IC), the midbrain integration center of the ascending auditory system. The direct amygdalo-collicular projection may impose emotional content onto auditory processing at a relatively low level of the ascending auditory pathway. Moreover, this projection could mediate effects of auditory cortical activation that have been attributed to the direct cortico-collicular pathway. We hypothesize that the amygdalo-collicular projection modulates the integrative features of acoustic information processing in the IC based on emotional state and/or the emotional significance of recent sensory input. The project will examine how the amygdala modifies integrative auditory responses in the mustached bat's IC, where integrative auditory responses (termed combination-sensitive) analyze social and sonar vocalizations. The functional organization and origin of these responses in the IC and auditory brainstem are well understood. Connectional evidence suggests that amygdalo-collicular projection neurons contact combination-sensitive IC neurons. In Aim #1 of the proposed research, we will examine responses of single neurons or small clusters of neurons in the basolateral amygdala in response to simple acoustic signals and social and sonar vocalizations. The results will identify acoustic conditions under which the amygdalo-collicular pathway is active, and also develop a physiological "signature" to identify amygdalo-collicular neurons. Aim #2 will use anterograde and retrograde tract tracing to examine the organization of the amygdalo-collicular projection and circuits relating the amygdala, auditory cortex, and IC. Aim #3 will examine how chemical and electrical stimulation of the amygdala affects acoustic information processing for simple acoustic signals and complex vocalizations across the IC, using multi-channel recording methods. Aim #4 will test, using non-invasive cortical cooling, whether the amygdala affects IC neurons primarily through its direct pathway, or through its connections to auditory cortico-collicular neurons. Relevance: These studies will provide a better understanding of how our processing of acoustic signals including speech is modified by emotion-laden sounds or by our emotional state. They may further our understanding of the role of the amygdala in auditory learning. This work may also improve our understanding of the role of emotional centers in abnormal auditory perceptions such as tinnitus.