Collicular influence on auditory thalamic neurons

丘脑对听觉丘脑神经元的影响

• 批准号: 6865356
• 负责人: PHILIP H SMITH
• 金额: $ 25.39万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-15 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6865356
• 关键词: Collicular; influence; auditory; thalamic; neurons

DESCRIPTION (provided by applicant): We have shown that both excitatory (glutamatergic) and inhibitory (GABAergic) cells in the inferior colliculus (IC) project to and synapse on cells in the auditory thalamus (MGB). Our long-term objective is to understand the role of these excitatory and inhibitory IC inputs in shaping the responses of cells in the MGB. The sensory thalamus was once considered to be a simple relay center whose cells received ascending sensory information and passively sent it on to the cortex. Over the past 3 decades it has become apparent that this is not the case and that thalamic cells can function in two different response modes, "burst" and "tonic" which depend on the activation or inactivation of a voltage sensitive calcium conductance. Depending upon which mode the cell is in drastically alters their spike response to ascending excitatory synaptic messages and thus changes their input to the cortex in response to sensory stimuli (see Sherman, '01). In addition, the synchronized response of populations of thalamic cells while in the burst mode are believed to be responsible for the EEG oscillations seen during slow wave sleep and during some types of generalized epileptic seizures (see McCormick and Bal, '97). Recent evidence primarily from our lab has indicated that an added level of complexity is found in the auditory thalamus. Here 1) in contrast to other sensory thalamic nuclei, the ascending synaptic information is in the form of both excitation and inhibition 2) this ascending sensory input may be influencing auditory thalamic cells that do not necessarily display the two different response modes and 3) this ascending sensory input from the IC to some cells in the MGB may show synaptic plasticity. Thus, models of thalamic function that have been created using other sensory systems may not be applicable to the auditory thalamus. In order to better understand the similarities and/or differences in auditory thalamic processing of sensory information it is important to determine 1) how and when the excitatory and inhibitory IC inputs are active and thus influencing thalamic neurons 2) whether these inputs are influencing cells that can respond either in one mode or two and 3) whether stimulation of the collicular inputs can generate synaptic plasticity (LTP) in certain MGB cells and what mechanism of potentiation is involved. The proposed experiments will help to answer these questions.

描述（由申请人提供）：我们已经证明下丘（IC）中的兴奋性（谷氨酸能）和抑制性（GABA能）细胞都投射到听觉丘脑（MGB）中的细胞并在其上形成突触。我们的长期目标是了解这些兴奋性和抑制性 IC 输入在塑造 MGB 细胞反应中的作用。 感觉丘脑曾经被认为是一个简单的中继中心，其细胞接收上行的感觉信息并被动地将其发送到皮质。在过去的三十年里，很明显事实并非如此，丘脑细胞可以以两种不同的响应模式发挥作用，“爆发”和“强直”，这取决于电压敏感钙电导的激活或失活。根据细胞所处的模式，细胞会大幅改变其对上行兴奋性突触消息的尖峰反应，从而改变其对皮质的输入以响应感觉刺激（参见 Sherman，'01）。此外，丘脑细胞群在突发模式下的同步反应被认为是造成慢波睡眠期间和某些类型的全身性癫痫发作期间看到的脑电图振荡的原因（参见 McCormick 和 Bal，'97）。主要来自我们实验室的最新证据表明，听觉丘脑的复杂性更高。这里 1) 与其他感觉丘脑核相反，上行突触信息同时采用兴奋和抑制的形式 2) 这种上行感觉输入可能会影响听觉丘脑细胞，而听觉丘脑细胞不一定显示两种不同的反应模式 3)从 IC 到 MGB 中某些细胞的上行感觉输入可能表现出突触可塑性。因此，使用其他感觉系统创建的丘脑功能模型可能不适用于听觉丘脑。 为了更好地理解听觉丘脑处理感觉信息的相似性和/或差异，重要的是确定 1) 兴奋性和抑制性 IC 输入如何以及何时活跃，从而影响丘脑神经元 2) 这些输入是否正在影响以下细胞：可以以一种或两种模式作出反应，3) 刺激丘脑输入是否可以在某些 MGB 细胞中产生突触可塑性 (LTP)，以及涉及什么增强机制。所提出的实验将有助于回答这些问题。