Fast Electrical Oscillations in Somatosensory Cortex

也许最古老的，最广泛认可的，最不了解的电现象，人类大脑在疾病和健康是其特征性的大幅度电振荡。最近，在理解振荡和大脑功能之间的关系方面取得了重大进展。伽马绑定中的皮层电振荡（约40 Hz），以及更高频率的快速和非常快的振荡（FO和VFO;分别约300和500 Hz），似乎在感觉皮层的时间编码中发挥作用。然而，它们的功能意义和潜在的细胞机制仍然是一个猜测和争议的问题。在本实验系列中，我们解决了这两个问题，结合在体内三维细胞外记录与细胞内记录和标记，研究神经回路负责产生和传播快速振荡的后内侧桶子场（PMBSF）的大鼠体感皮层。首先，我们将我们的结果推断在听觉系统有关丘脑调制皮层伽玛振荡，体感系统。在这样做的时候，我们将建立结构和功能的类比，应该强烈支持或反驳不同的丘脑系统参与产生或调制皮层伽马振荡的假说，躯体感觉系统。在这样做的过程中，我们将建立结构和功能的类比，应该强烈支持或反驳有关不同的丘脑系统参与皮质伽马振荡的产生或调制的假设。其次，我们将确定丘脑诱发的伽玛振荡的PMBSF的神经发生器，并将这些结果与我们从听觉皮层的细胞内记录的结果进行比较，以评估我们的假设，即皮层伽玛振荡的产生可能是基于两种感觉方式中的常见细胞类型，而不是依赖于专门的神经起搏器。第三，我们将测量单触须刺激的时空响应场，以建立刺激诱发的伽玛，FO和VFO在PMBSF中的躯体组织和二维形状，并更好地预测每个振荡类如何有助于相邻皮质柱之间的时间相互作用。第四，我们将评估可能的时空互动模式的快速振荡测量的表面PMBSF，诱发多触须刺激。通过观察每类快速振荡如何从PMBSF中的多个起始点传播，并在场的子区域内以相位敏感的方式相互作用，我们期望更好地理解这些振荡如何编码与物体的顺序瞬时触须接触的精确定时，和/或它们如何在由共同和更长时间的刺激激活时同步多个皮质柱中的活动。最后，我们将探讨在皮层内和细胞内的水平，支持时间整合的PMBSF和组织学标签内的每个振荡类和识别神经元和他们的进程负责这种spatio整合的阈下和阈上事件。

Perhaps the oldest, most widely recognized, and least understood electrical phenomena of the human brain in sickness and in health are its characteristic large amplitude electrical oscillations. Recently, there has been a major advance towards understanding the relationship between oscillations and brain function. Electrocortical oscillations in the gamma bind (approximately 4o Hz), and much higher frequency fast and very fast oscillations (FO and VFO; approximately 300 and 500 Hz, respectively), appear to play a role in temporal coding in sensory cortex. Yet, their functional significance and underlying cellular mechanisms are still a matter of speculation and controversy. In the present experimental series, we address both of these issues by combining in vivo three dimensional extracellular recording with intracellular recording and labeling to study the neural circuitry responsible for generating and propagating fast oscillations in the posteromedial barrel subfield (PMBSF) of rat somatosensory cortex. First, we will extrapolate our results in the auditory system concerning thalamic modulation of cortical gamma oscillations, to the somatosensory system. In so doing, we will establish structural and functional analogies that should strongly support or refute hypotheses about the participation of distinct thalamic systems in the generation or modulation of cortical gamma oscillations, to the somatosensory system. In so doing, we will establish structural and functional analogies that should strongly support or refute hypotheses about the participation of distinct thalamic systems in the generation or modulation of cortical gamma oscillations. Second, we will determine the neural generators of thalamically evoked gamma oscillations in the PMBSF and compare these to our results from intracellular recordings in auditory cortex to evaluate our hypotheses that the generation of cortical gamma oscillations may be based on common cell types in both sensory modalities and not rely on specialized neural pacemakers. Third, we will measure the spatiotemporal response field of single vibrissa stimulation to establish the somatotopic organization and two dimensional shape of stimulus evoked gamma, FO and VFO in the PMBSF and to better anticipate how each oscillatory class could contribute to temporal interactions between adjacent cortical columns. Fourth, we will evaluate possible spatiotemporal interaction patterns of fast oscillations measured at the surface of the PMBSF, evoked by multi-vibrissal stimulation. By looking at how each class of fast oscillations may propagate from multiple start points in the PMBSF and interact in phase sensitive ways within sub-regions of the field, we expect to better understand how these oscillations may encoded the precise timing of sequential transient vibrissal contact with objects and/or how they may synchronize activity in multiple cortical columns when activated by a common and more prolonged stimulus. Finally, we will explore both sub- and suprathreshold events at the intracortical and intracellular level that support temporal integration of each oscillatory class within the PMBSF and histologically label and identify neurons and their processes responsible for this spatio integration.