Functional Organization of Inferior Colliculus

下丘的功能组织

• 批准号: 7060876
• 负责人: GEORGE D POLLAK
• 金额: $ 32.38万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-07-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7060876
• 关键词: Chiroptera; animal communication behavior; auditory pathways; binaural hearing; electrophysiology; gamma aminobutyrate; inferior colliculus; neural information processing; neural inhibition; neuropharmacology; neurotransmitter antagonist; sound frequency

DESCRIPTION (provided by applicant): The overall goals of this proposal are to determine what response transformations occur between lower nuclei and the inferior colliculus (IC), what impact each lower nucleus has in causing those transformations and what functional significance might accrue to those transformations. This will be accomplished by evaluating the processing of species-specific signals in the brainstem auditory system of Mexican free-tailed bats. These are highly social mammals that employ a rich repertoire of communication calls for a wide variety of social interactions, including mother-infant interactions, courtship, agonistic encounters, and territoriality. Studies conducted during the previous grant period have shown that responses of IC neurons to social communication signals undergo substantial transformations, and those transformations are strongly shaped by inhibition. The proposed studies will investigate the specific inhibitory influences that lower nuclei have on the IC. Particular attention will be given to three main sources of inhibitory innervation; 1) the ipsilateral DNLL; 2) the columnar division of the ventral nucleus of the lateral lemniscus (VNLLc); and 3) its multipolar division (VNLLm). The DNLL provides GABAergic inhibition to the IC while the VNI.I. divisions provide either glycinergic (VNLLc) or a mixed glycineric and GABAergic innervation (VNLLm) to the IC. Together, the projections from ipsilateral DNLL and the two divisions of the VNLL provide more than half of the total inhibitory innervation of the IC. Following from the above, experiments are proposed that will answer 2 main questions. First, how do neurons in the two regions of the VNLL respond to species-specific calls and how are their response features, evoked by both tones and complex signals, shaped by the excitatory and inhibitory innervation they receive? These questions will be answered by recording from neurons in each VNLL region before and then while inhibition is blocked by iontophoretic application of bicuculline or strychnine. Second, what influences do the GABAergic inputs from the ipsilateral DNLL have on IC responses evoked by both tones and complex signals, and how do those influences compare to the influences of glycinergic and/or GABAergic inhibition fi'om the VNLL subdivisions? These questions will be answered by recording from IC neurons before, during and after reversible inactivation of each of the lower nuclei. Taken together these data will provide a more complete picture of the inhibitory discharge trains that act on the IC in response to simple and complex signals. They will also reveal what impacts the inhibition from each nucleus have in shaping IC responses to simple and complex signals, including communication signals that convey unique categories of information. The elucidation of the processing of communication calls may provide insights into the processing of speech. The roles of inhibition in this processing may be especially relevant for the decline of speech perception in the elderly, which is correlated with age related loss of GABAergic neurons in the auditory system.

描述(申请人提供)：本提案的总体目标是确定下核和下丘(IC)之间发生什么反应转换，每个下核在引起这些转换中有什么影响，以及这些转换可能产生什么功能意义。这将通过评估墨西哥无尾蝙蝠脑干听觉系统中特定物种信号的处理来实现。它们是高度社会化的哺乳动物，它们利用丰富的交流要求进行各种各样的社会互动，包括母婴互动、求偶、争斗相遇和领地。在前一次授予期间进行的研究表明，IC神经元对社会交流信号的反应经历了实质性的转变，而这些转变强烈地受到抑制的影响。拟议的研究将调查低核团对IC的特定抑制影响。将特别注意抑制神经支配的三个主要来源：1)同侧DNLL；2)外侧丘脑腹核的柱状分裂(VNLLc)；以及3)其多极分裂(VNLLm)。DNLL向IC提供GABA能抑制，而VNI.I.部门向IC提供甘氨酸能(VNLLc)或甘氨酸和GABA能混合神经支配(VNLLm)。来自同侧DNLL和VNLL的两个分支的投射加在一起，提供了IC全部抑制性神经支配的一半以上。在此基础上，提出了解决两个主要问题的实验。首先，VNLL的两个区域的神经元如何对特定物种的叫声做出反应，以及它们的反应特征是如何由它们接收的兴奋性和抑制性神经支配塑造的，由音调和复杂信号引起的？这些问题将通过记录每个VNLL区域的神经元在之前和之后，而抑制被离子导入应用荷包牡丹碱或士的宁阻断。第二，来自同侧DNLL的GABA能输入对音调和复合信号诱发的IC反应有什么影响，这些影响与甘氨酸和/或GABA能抑制对VNLL亚区的影响相比如何？这些问题将通过记录每个下核团可逆失活之前、期间和之后的IC神经元来回答。综合起来，这些数据将提供对IC响应简单和复杂信号的抑制性放电序列的更完整的图景。他们还将揭示来自每个核的抑制在塑造IC对简单和复杂信号的反应方面的影响，包括传达独特类别信息的通信信号。对通信呼叫处理的阐明可以为语音处理提供洞察。抑制在这一过程中的作用可能与老年人言语知觉的下降特别相关，这与听觉系统中GABA能神经元的年龄相关损失有关。