Behavioral and physiological studies of sound localization

描述（由申请人提供）：本项目的总体目标是了解声音定位的神经机制。这些结果将帮助我们理解大脑如何整合来自双耳的听觉信息，并产生头部，眼睛和耳朵的定向运动，以允许对目标进行近距离的视觉和听觉检查。这些实验旨在测试听觉脑干中出现的两个回路的相对作用，以编码定位声音所需的线索，并产生将头部，眼睛和耳朵定向到声学目标的运动程序。一个回路涉及下丘和上级丘的中脑核团，其输出从上级丘的深层到脑干中的运动回路。另一个回路涉及从下丘到内侧膝状体和初级听觉皮层的投射。通过使皮层或中脑失活，这两个回路在定向行为中的相对作用将被确定。第二个目的是通过测试前庭系统半规管失活后的反射来检查前庭耳反射。我们将堵塞半规管，并假设这将大大减弱反射。在具有移动的瞳孔的动物中，假设反射用于稳定听觉世界，就像前庭眼反射在头部运动时稳定视网膜上的图像一样。最后的目的将研究的电路，移动耳廓作为一个模型的运动系统，并比较它与著名的眼电路。我们还将研究固定耳廓对声音定位性能的影响。 空间听觉是听觉系统的一项重要的基本功能。人类患者的双耳功能缺陷可能导致在嘈杂的房间中理解对话的相当大的困难，这是听力受损者最常见的抱怨，并可能导致严重的社交退缩。

DESCRIPTION (provided by applicant): The overall aim of this project is to understand the neural mechanisms of sound localization. These results will help us understand how the brain integrates auditory information from the two ears and produces orienting movements of the head, eyes, and ears to allow close visual and auditory inspection of targets. The experiments are designed to test the relative roles of two circuits that arise in the auditory brainstem to encode the cues necessary to localize sounds and generate the motor programs that orient the head, eyes and ears to the acoustic target. One circuit involves the midbrain nuclei of the inferior and superior colliculi with outputs to motor circuits in the brainstem from the deep layers of the superior colliculus. The other circuit involves projections from the inferior colliculus to the medial geniculate and primary auditory cortex. By inactivating the cortex or the midbrain, the relative roles of these two circuits in orienting behavior will be determined. The second aim will examine the vestibulo-auricular reflex by testing for the reflex following inactivation of the semicircular canals in the vestibular system. We will plug the semicircular canals and hypothesize that this will greatly attenuate the reflex. In animals with mobile pinnae, it is hypothesized that the reflex serves to stabilize the auditory world just like the vestibulo-ocular reflex stabilizes images on the retina in the presence of head movements. The final aim will study the circuitry that moves the pinna as a model motor system and compare it with the well-known oculomotor circuit. We will also examine the effect of immobilizing the pinna on sound localization performance. PUBLIC HEALTH RELEVANCE: Spatial hearing is an important basic function of the auditory system. Defects in binaural function in human patients can lead to considerable difficulty in understanding conversations in a noisy room, which is the most common complaint of the hearing-impaired and can lead to severe social withdrawal.