Physiological bases of magnetoencephalography

脑磁图的生理基础

• 批准号: 7211337
• 负责人: Yoshio Okada
• 金额: $ 27.63万
• 依托单位: UNIVERSITY OF NEW MEXICO
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-03-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7211337
• 关键词: Accounting; Address; Algorithms; Animals; Apical; Appendix; Area; Brain; Calcium; Calcium Channel; Calcium Spikes; Cavia; Cerebellum; Cerebral cortex; Complex; Condition; Dendrites; Depth; Distal; Electroencephalography; Epilepsy; Event; Evoked Potentials; Exhibits; Family suidae; Generations; Hippocampus (Brain); Human; In Vitro; Long-Term Potentiation; Magnetoencephalography; Measurement; Measures; Mediating; Modeling; Monkeys; Neocortex; Neurons; Optics; Physiological; Potassium Channel; Preparation; Property; Protocols documentation; Research; Role; Shapes; Signal Transduction; Site; Slice; Sodium Channel; Solutions; Somatosensory Cortex; Structure; Surface; Sus scrofa; Synapses; Techniques; Testing; Time; Tissues; Trigeminal System; Turtles; Work; base; channel blockers; delayed rectifier potassium channel; density; dipole moment; extracellular; in vivo; insight; magnetic field; median nerve; neocortical; network models; neuronal cell body; response; theories

DESCRIPTION (provided by applicant): We propose to study the physiological basis of MEG and EEG in a slice preparation of the pig primary somatosensory cortex (SI). Earlier we studied the same issue in isolated turtle cerebellum in vitro and guinea pig hippocampal slices. In the previous cycle, we showed for the first time that three distinct types of signals - intra- and extracellular field potentials and magnetic field - can be quantitatively explained with our mathematical network model based on RD Traub's and thus provided a fundamental understanding of origin of MEG in hippocampus. Based on these results we are now ready to tackle the same issue in the most difficult, but most important structure for MEG and EEG, i.e. the cerebral cortex. In a related project, we have studied the somatic evoked potentials (SEPs) and magnetic fields (SEFs) produced by the porcine SI cortex. This research has led to new insights into the genesis of MEG and EEG signals in the SI cortex in vivo. We propose to extend our in vitro work to the porcine SI cortex to study the origin of these signals in more detail. Specifically, we will address four aims. (1) Determine whether there is an invariance in the maximum current that can be generated per unit cross-sectional area of the cortex. Our previous studies indicate such an invariance (approximately equals 1 nA-m/mm2) across species and brain structures. This issue is crucial since it can provide an important physiological constraint on inverse solution algorithms used to interpret human MEG and EEG. (2) Determine the basis for another invariance found across species, i.e. the invariance in direction of the current underlying the first cortical response called N20. This is always from a deep to a superficial layer in humans, monkey and pig. We will test a hypothesis resulting from our in vivo SI study, i.e. it is due to an initial nearly instantaneous spread of activation from dendrites to the soma which then produces intracellular currents directed from the soma toward distal apical dendrites and also serves as the basis for backpropagation. (3) Determine the origin of the long-term potentiation (LTP) in the SI detected outside the brain in our in vivo study. This result can open the possibility for studying LTP in humans. We plan to determine its synaptic loci in vitro in the cortex of the animal exhibiting LTP in vivo. (4) Determine effects of blocking specific active channels in cortical neurons on MEG and EEG signals. Our hippocampal slice study has shown the importance of calcium and C channel in the generation of MEG and EEG signals. We will study the role of various conductances by using selective channel blockers and measuring their effects with intracellular and extracellular potential recordings and MEG. The role of calcium-mediated current in evoked response will be determined by a combination of optical measurements of intracellular calcium concentration, intra- and extracellular potentials.

描述（由申请人提供）：我们建议研究MEG和EEG的生理基础，以在猪主要体感皮层（SI）的切片制备中进行。早些时候，我们在体外和豚鼠海马切片中研究了相同的问题。在上一个周期中，我们首次表明，可以使用基于RD Traub的数学网络模型来定量解释三种不同类型的信号 - 细胞内和细胞外场电位和磁场，因此可以对海马群岛中MEG起源的基本了解。基于这些结果，我们现在准备在MEG和EEG最困​​难但最重要的结构中解决相同的问题，即大脑皮层。在相关的项目中，我们研究了由猪Si Cortex产生的体细胞诱发电位（SEP）和磁场（SEF）。这项研究导致了对体内Si Cortex中MEG和EEG信号的起源的新见解。我们建议将我们的体外工作扩展到猪Si Cortex，以更详细地研究这些信号的起源。具体来说，我们将解决四个目标。 （1）确定最大电流中是否有不变性，可以生成皮层的每个单位横截面区域。我们先前的研究表明，这种不变性（大约等于1 Na-m/mm2），跨物种和大脑结构。这个问题至关重要，因为它可以对用于解释人类MEG和EEG的逆溶液算法提供重要的生理约束。 （2）确定跨物种发现的另一种不变性的基础，即在第一个称为N20的首个皮质反应的电流方向上的不变性。这总是从人类，猴子和猪的深层到浅层层。我们将通过体内SI研究产生的假设来检验，即，这是由于最初的几乎瞬时从树突向SOMA激活的瞬时扩散，然后产生从躯体朝着远端顶端树突的细胞内电流，也是反射性磁性的基础。 （3）在我们的体内研究中确定在大脑外检测到的SI中长期增强（LTP）的起源。该结果可以为研究人类研究LTP的可能性开放。我们计划在体内表现出LTP的动物皮质中确定其突触基因座的体外。 （4）确定在MEG和EEG信号上阻断皮质神经元中特定活性通道的影响。我们的海马切片研究表明，钙和C通道在MEG和EEG信号的产生中的重要性。我们将通过使用选择性通道阻滞剂并用细胞内和细胞外电势记录和MEG测量各种电导的作用。钙介导的电流在诱发反应中的作用将取决于细胞内钙浓度，细胞内和细胞外电位的光学测量结果的结合。