MEDIAL SUPERIOR OLIVARY CIRCUITRY

内侧上级橄榄（MSO）被认为在声音中起主要作用 本地化 它是听觉中枢神经系统的起始部位， 来自双耳的声音诱发的活动会聚在个体上并使个体兴奋， 神经元 有人提出，通过比较，位于这里的细胞可以 这些双耳输入提取并响应重要的时间线索， 在这个输入信号中可用。 这些时间线索随着声音的变化而变化 改变方位角空间中的位置，并且还提出， MSO细胞群的不同成员仅对以下物质作出最佳反应： 从该空间中的特定点生成的那些双耳线索。 因此，外部空间的“地图”的重要方面被提取出来， 在一群选择性敏感的神经元中进行神经编码。 不幸的是，从正面记录的巨大困难 鉴定的MSO细胞，使用标准体内细胞外和 细胞内的方法，阻碍了这种假设的验证。 我们打算从MSO细胞中进行体外细胞内记录 (and来自输入到MSO的橄榄周核中的细胞）和体内 使用高阻抗从MSO轴突的轴突内记录 神经生物素填充的玻璃电极。 在体外，我们将描述 MSO细胞的内在膜特征和突触输入， 区分在完成任务中可能重要的方面， 上述的本地化任务。 然后我们将研究 标记的单元的方面，以确定本地电路，如果某些 细胞亚型表现出独特的生理机能。 在体内，我们将记录 轴突内从MSO细胞的轴突，因为它们接近下 丘在外侧丘系，并表征他们的反应， 单耳和双耳刺激。 接下来我们将分析（1） 标记的轴突，在光镜和电镜水平，以确定 MSO细胞对其他听觉核团的影响; 2）MSO细胞的位置和 类型的回填MSO细胞体，以确定1）细胞类型2）其 突触输入3）是否不同类型的细胞编码不同的听觉 4）如果它们以任何形式的顺序（地图）排列， 这些特征（例如，用于编码空间位置的那些特征）。

The medial superior olive (MSO) is presumed to play a major role in sound localization. It is the initial site in the auditory CNS where sound-evoked activity from both ears converges on and excites individual neurons. It has been proposed that cells located here can, by comparing these binaural inputs, extract and respond to important temporal cues available in this incoming signal. These temporal cues change as a sound changes location in azimuthal space and it has also been proposed that different members of the MSO cell population respond optimally to only those binaural cues generated from a particular point(s) in this space. Thus, important aspects of the "map" of external space are extracted and neurally encoded in a population of selectively sensitive neurons. Unfortunately, the great difficulty in recording from positively identified MSO cells, using standard in vivo extracellular and intracellular methods, has hindered verification of such hypotheses. We intend to do both in vitro intracellular recordings from MSO cells (and from cells in periolivary nuclei inputting to MSO) and in vivo intraaxonal recordings from MSO axons using high impedance Neurobiotin-filled glass electrodes. In vitro, we will characterize intrinsic membrane features of - and synaptic inputs to - MSO cells to distinguish aspects that could be important in accomplishing the localization tasks described above. We will then study the anatomical aspects of the labeled cell to determine local circuitry and if certain cell subtypes show unique physiology. In vivo, we will record intraaxonally from axons of MSO cells, as they approach inferior colliculus in lateral lemniscus, and characterize their responses to monaural and binaural stimuli. We will subsequently analyze 1) the labeled axon, at light and electron microscopic levels, to determine the influence of MSO cells on other auditory nuclei and 2) the location and type of the backfilled MSO cell body to determine 1) cell type 2) its synaptic input 3) whether different cell types encode different auditory features and 4) if they are arranged in any sort of order (map) based on such features (e.g. those features used to encode location in space).