Functional anatomy of the auditory pathways

描述(申请人提供)：听觉系统由上行通路和下行通路组成，上行通路将信息从耳朵传输到能感知声音的大脑皮层，而大脑皮层下行通路调节上行信息的处理和流动。下行通路被认为在多种功能中发挥作用，例如选择性注意和辨别语音，但由于缺乏关于神经回路的信息，这些作用的理解受到阻碍。最大的下行通路之一是从皮质到下丘(IC)，这是AT中的一个突出的中脑结构，处理几乎所有的上行听觉信息。皮质投射激活使用神经递质GABA和乙酰胆碱的皮质下回路。这些递质在IC的正常功能、耳鸣等功能障碍以及与衰老相关的功能衰退中发挥着重要作用。目前的建议集中在皮质下行投射和皮质下回路之间的关系，这些回路使用GABA或乙酰胆碱来影响IC。拟议的实验将确定IC的乙酰胆碱输入的来源，并表征这些输入的细胞靶标。这些实验还将确定皮质投射是否与使用GABA或乙酰胆碱的皮质下细胞直接联系，并对IC进行神经支配。这一结果将提供有关下行听觉通路和特定皮质下回路的基本信息。

DESCRIPTION (provided by applicant):The auditory system consists of ascending pathways that transmit information from the ear to the cortex, where sound is perceived, and descending pathways from the cortex that modulate the processing and flow of ascending information. The descending pathways are believed to play a role in a variety of functions, such as selective attention and discrimination of speech sounds, but understanding these roles is hindered by a lack of information on the neural circuitry. One of the largest descending pathways is from cortex to the inferior colliculus (IC), a prominent midbrain structure In at processes almost all ascending auditory information. Cortical projections activate subcortical circuits that use the neurotransmitters GABA and acetylcholine. These transmitters play prominent roles in the IC in normal function, in dysfunction such as tinnitus and in declining function associated with aging. The current proposal is focused on the relationships between descending cortical projections and the subcortical circuits that use GABA or acetylcholine to affect the IC. The proposed experiments will identify the source of acetylcholine inputs to the IC and characterize the cellular targets of those inputs. The experiments will also determine whether cortical proejctions make direct connections with the subcorical ceils that use GABA or acetylcholine and innervate the IC. The results will provide essential information on descending auditory pathways and specific subcortical circuits.