Behavioral and physiological studies of sound localization

描述（由申请人提供）：这个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两只耳朵的听觉信息，并产生头部、眼睛和耳朵的定向运动，以便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，它们编码声音定位所需的线索，并产生运动程序，使头部、眼睛和耳朵朝向声音目标。其中一个回路涉及上丘和下丘的中脑核，并从上丘的深层向脑干的运动回路输出信号。另一个回路涉及从下丘到内侧膝状皮层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中半环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。在有活动耳廓的动物中，有一种假设是，这种反射起到了稳定听觉世界的作用，就像前庭-眼反射在头部运动时稳定视网膜上的图像一样。最终目的是研究将耳廓作为模型运动系统的运动电路，并将其与众所周知的动眼电路进行比较。我们还将研究固定耳廓对声音定位性能的影响。

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.