Intrinsic Bursting and Information Transmission by Visual Corticotectal Neurons

大脑的感觉新皮层对于感觉和知觉是必不可少的，这导致了人们对了解该组织的功能特性的强烈努力。 锥体细胞约占皮质中所有神经元的80%，第5层中一种特殊类型的锥体细胞显示出内在的活动爆发，是锥体亚群中最具解剖学和生理学特征的细胞之一。这些神经元具有特别厚的顶端树突，它们投射下行轴突，这些轴突分支以支配大脑的多个皮层下区域。 上级丘是由这些爆裂的锥体神经元支配的皮质下结构之一，并对视觉刺激作出反应。 已知这种“皮质顶盖”锥体神经元强烈影响上级丘神经元的反应特性，但这种影响的机制仍然未知。 例如，还不知道感受野特性是否通过皮质顶盖输入直接传递到上级丘神经元，或者皮质顶盖的影响是否调节对上级丘神经元的其他输入。 该建议的重点是皮质顶盖神经元影响清醒家兔上级丘的靶点，以及EEG状态（警觉与困倦状态）如何影响皮质顶盖通信。 首先，Swadlow博士将获得关于单个皮质顶盖神经元对上级丘的突触影响以及这种影响的动力学的全面的、全局的观点。 他将通过对单个皮质顶盖神经元的脉冲（爆发和单个尖峰）在上级丘内产生的单突触电流进行电生理学检查来完成这一工作。 接下来，Swadlow博士将获得单个皮质顶盖神经元对上级丘内特定神经亚群成员的突触影响的局部视图，以及这种影响的动力学。 为了做到这一点，他将同时从皮质顶盖神经元和上级丘内的特定亚群获得细胞外电生理记录，并应用互相关方法来推断突触连接。 此外，Swadlow博士将记录皮质顶盖神经元的细胞内，并检查与爆发行为相关的阈下感觉事件。 拟议的研究将提供重要的见解，既感觉皮层信息在清醒的感知主体中处理的方式，也是皮层神经元如何与大脑远端区域的神经元通信并影响它们。 如果我们要了解清醒的哺乳动物的感知机制，这些信息是至关重要的。 拟议的研究也将进一步培训未来的神经生物学家通过参与PI的研究本科生。

Award Abstract The sensory neocortex of the brain is essential for sensation and perception, and this has led to an intense effort to understand the functional properties of this tissue. Pyramidal cells comprise about 80% of all neurons in the cortex, and a special type of pyramidal cell in layer-5 that shows intrinsic bursts of activity is one of the most anatomically and physiologically distinctive of pyramidal sub-populations. These neurons have especially thick apical dendrites and they project descending axons that branch to innervate multiple subcortical areas of the brain. The superior colliculus is one of the subcortical structures innervated by these bursting pyramidal neurons and is responsive to visual stimulation. Such "corticotectal" pyramidal neurons are known to strongly influence the response properties of neurons in the superior colliculus, but the mechanism of this influence is still unknown. It is not known, for example, whether receptive field properties are conveyed to superior colliculus neurons directly by corticotectal input, or whether the corticotectal influence modulates other input to the neurons of the superior colliculus. This proposal focuses on the means by which corticotectal neurons influence their targets in the superior colliculus in awake rabbits, and how EEG state (alert vs. drowsy state) may affect corticotectal communication. First, Dr. Swadlow will gain a comprehensive, global view of the synaptic impact of single corticotectal neurons on the superior colliculus, and the dynamics of this impact. He will do this by electrophysiological examination of monosynaptic currents generated within the superior colliculus by the impulses (bursts and single spikes) of single corticotectal neurons. Next, Dr. Swadlow will gain a local view of the synaptic impact of single corticotectal neurons on members of specific neural sub-populations within the superior colliculus, and the dynamics of this impact. To do this, he will obtain simultaneous extracellular electrophysiological recordings from corticotectal neurons and from specific sub-populations within the superior colliculus, and apply cross-correlation methods to infer synaptic connectivity. In addition, Dr. Swadlow will record intracellularly from corticotectal neurons and examine the sub-threshold sensory events related to bursting behavior. The proposed studies will provide important insights into both the manner in which sensory cortical information is processed in an awake, perceiving subject and how cortical neurons communicate with and influence neurons in distant regions of the brain. Such information is crucial if we are to understand the mechanisms of perception in awake, perceiving mammals. The proposed studies will also further the training of future neurobiologists through involvement of undergraduate students in the PI's research.