STATE DEPENDENT CONTROL OF RETINOGENICULATE TRANSMISSION

描述：(摘自调查员的摘要)现在很明显， 丘脑背侧膝状体外侧核(LGN) 而不是简单地将视网膜信息传递到视觉皮质。 相反，此结构充当动态筛选器，确定什么、何时 以及有多少视网膜信息被传递到视觉皮质。这个 控制这种过滤的细胞因素是复杂的神经支配。 LGN细胞的模式和固有的膜特性。这些都有 已经在体内使用麻醉、麻痹的动物进行了广泛的研究， 或使用丘脑切片制剂进行体外实验。问题是我们 缺乏关于这些细胞因子如何与更多 动态因素，如行为状态或眼球运动，以控制 通过LGN进行视觉处理的效果。动态因素可以 只能在清醒的、行为正常的动物身上进行研究。的第一个目标 这个建议是为了了解LGN中的细胞是如何过滤视网膜的 在清醒状态下发出的信号。在清醒、克制的猫身上，我们 计划记录LGN中单个神经元的活动，并研究如何 细胞兴奋性和视觉反应方面受 昏昏欲睡、定向警觉、注意力集中等状态。 我们通过训练猫执行各种不同的动作来操纵清醒状态 视觉运动任务，我们通过监测动物来评估行为状态 S对这些任务进行了表演，并通过记录脑电活动。第二 这项建议的目标是了解眼球运动和 眼眶位置对LGN神经元的传递特性有调节作用。 我们计划在之前、期间和之后监测LGN细胞的活动 各种注视和扫视任务。录制是使用 动物的头部在固定位置和凝视通过使用 巩膜探查线圈技术。最后，我们将开始探索一些 LGN动态调节的细胞机制 活动。具体来说，我们将确定条件(即， 行为状态、眼球运动或眼眶位置)。这会导致LGN 细胞在紧张性或爆发式激发模式下做出反应。爆裂 响应反映了电压依赖的低阈值的激活 钙电导，并允许超极化的LGN细胞响应 当去极化事件达到峰值阈值时，积极行动。建议数 实验解决了神经科学面临的一个重大而持久的挑战 这就是将认知行为与单个神经元的行为联系起来。 更具体地说，我们希望这些研究提供更好的 对丘脑环路在多种疾病中作用的认识 唤醒、视觉注意力和眼球运动的各个方面。另一个 这个建议的重要方面是理解大脑是如何 调节视网膜化信号期间LGN细胞的猝发反应 变速箱。LGN细胞的爆发式放电服务于一般的实验 用于理解睡眠-觉醒周期和细胞基础的模型 病理性丘脑皮质节律。

DESCRIPTION: (from the investigator's abstract) It is now clear that the lateral geniculate nucleus (LGN) of the dorsal thalamus functions as more than a simple relay of retinal information to the visual cortex. Instead, this structure acts as a dynamic filter, determining what, when and how much retinal information gets passed on to visual cortex. The cellular factors that control this filtering are the complex innervation patterns and intrinsic membrane properties of LGN cells. These have been studied extensively in vivo using anesthetized, paralyzed animals, or in vitro with a thalamic slice preparation. The problem is that we lack information about how these cellular factors interact with more dynamic factors, such as behavioral state or eye movements, to control the efficacy of visual processing through the LGN. Dynamic factors can only be studied in an awake, behaving animal. The first objective of this proposal is to understand how cells in the LGN filter retinal signals during states of wakefulness. In awake, restrained cats, we plan to record the activity of single neurons in the LGN and examine how aspects of cellular excitability and visual responses are influenced by states such as drowsiness, orienting vigilance, and focal attention. We manipulated the awake state by training cats to perform various visuomotor tasks, We evaluate behavioral state by monitoring the animal s performance on these tasks and by recording EEG activity. The second objective of this proposal is to understand how eye movements and orbital position modulate the transfer characteristics of LGN neurons. We plan to monitor the activity of LGN cells before, during and after various fixation and saccade tasks. Recordings are conducted with the animal's head in a fixed position and gaze is monitored by using the scleral search coil technique. Finally, we will begin to explore some of the cellular mechanisms underlying the dynamic modulation of LGN activity. Specifically, we will determine the conditions (i.e., behavioral state, eye movement or orbital position). which cause LGN cells to respond in either a tonic or burst firing mode. Burst responses reflect the activation of a voltage-dependent low threshold Ca2+ conductance, and permit hyperpolarized LGN cells to respond vigorously when depolarizing events reach spike threshold. The proposed experiments address a major and enduring challenge for neuroscience which is to link cognitive behavior to the behavior of single neurons. More specifically, it is our hope that these studies provide a better understanding for the role played by thalamic circuitry in various aspects of arousal, visual attention, and eye movements. Another important aspect of this proposal is to understand how the brain regulates burst responses in LGN cells during retinogeniculate signal transmission. Burst firing in LGN cells serves a general experimental model for understanding the cellular bases of sleep-waking cycles and pathological thalamocortical rhythms.