NEURAL MECHANISMS OF BINAURAL HEARING

描述：(改编自《调查者摘要》)下丘 是许多神经中枢输入信息汇聚的主要场所。穿过 部分主要听觉结构--PI和His神经元的研究 小组已经确定了ITD表示中的转换，这些转换是 最好的解释是投入的汇聚。两种转换是(1) 提高了对ITD的调谐能力；(2)增加了具有以下特性的神经元数量 在较低水平记录的那些之间的中间。 ITD在上橄榄复合体中的功能太广泛，不能有效地 人口代码。然而，创新及科技发展署的强化功能，却接近 听觉丘脑的敏锐度。 IC中中间神经元的出现为我们提供了对 ITDS的神经表现。苏氏中间神经元的ITD功能 看起来有不对称的“锯齿”形状，并因此在 响应相对于来自SOC的输入的质心。此形状和 质心移位被认为是由收敛的抑制输入引起的 具有来自SOC的部分重叠的激励性输入。神经元敏感 通过相同的兴奋性输入汇聚到不同的ITD 具有不同重叠程度和强度的抑制输入 抑制力。通过这种方式，可以从表示中提炼出地点代码 使用一组粗略的延迟线进行折痕，与Jeffress模型形成对比 这意味着地点代码是在一个步骤中创建的，具有细粒度的延迟 台词。 拟议中的实验将检验灭活源的效果。 抑制输入对IC中ITD功能锐化和移位的影响 神经元。PI还将在失活过程中沉积顺行示踪剂 以及IC中的逆行示踪剂。解剖学实验，结合 随着记录和失活研究的进行，将提供全面的 集成电路中ITD加工及其收敛抑制作用的探讨 投入。

DESCRIPTION: (Adapted from the Investigator's Abstract) The inferior colliculus is a major site of convergence of inputs from many neural centers. Through studies of neurons in some of the main auditory structures, the PI and his group have identified transformations in the representation of ITDs that are best explained by the convergence of inputs. Two transformations are (1) sharpened tuning to ITDs and (2) increased numbers of neurons with properties intermediate between those recorded at lower levels. ITD functions in the superior olivary complex are too broad for an efficient population code. The sharpened ITD functions of the IC, however, approach the sharpness of those in the auditory thalamus. The emergence of intermediate neurons in the IC provides insights into the neural representations of ITDs. The ITD functions of suche intermediate neurons appear to have asymmetrical "saw-tooth" shapes and a consequent shift in the centroid of the response relative to inputs from the SOC. This shape and shifted centroid is purported to arise from inhibitory inputs that converge with partially overlapping, excitatory inputs from the SOC. Neurons sensitive to different ITDs would then be created by the same excitatory input converging with inhibitory inputs with different degrees of overlap and strength of inhibition. In this way, a place code could be refined from a representation creased using a coarse set of delay lines, in contrast to the Jeffress model that implies that a place code is created in one step with fine-grain delay lines. The proposed experiments will examine the effects of inactivating the sources of inhibitory inputs on the sharpening and shifting of ITD functions in IC neurons. The PI will also deposit an anterograde tracer into the inactivation site, and a retrograde tracer in the IC. The anatomical experiments, combined with the recording and inactivation studies, will provide a comprehensive approach to ITD processing in the IC and the role of converging inhibitory inputs.