Localized fMRI of heterogeneous neural responses

异质神经反应的局部功能磁共振成像

• 批准号: 8301873
• 负责人: Cheryl A. Olman
• 金额: $ 18.2万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-15 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8301873
• 关键词: Access to Information; Accounting; Affect; Animal Model; Area; Automobile Driving; Behavior; Biological Markers; Biological Neural Networks; Brain; Characteristics; Code; Complex; Computer Simulation; Coupling; Data; Dependence; Detection; Disease; Equilibrium; Event; Exhibits; Functional Magnetic Resonance Imaging; Funding; Goals; Grant; Human; Image; Imaging Device; Individual; Link; Literature; Masks; Measurement; Measures; Methodology; Minority; Modeling; Neural Inhibition; Neurons; Neurophysiology - biologic function; Neurosciences; Output; Pattern; Perception; Physiological; Play; Population; Protocols documentation; Psychology; Publications; Reporting; Research Personnel; Resolution; Sampling; Schizophrenia; Scientist; Seizures; Series; Shapes; Signal Transduction; Source; Stimulus; Structure; Techniques; Testing; Theft; Time; Visual; Visual Cortex; Work; area striata; base; blood oxygen level dependent; blood oxygenation level dependent response; design; hemodynamics; improved; inhibitory neuron; innovation; interest; neural model; neural patterning; neuroimaging; relating to nervous system; research study; response; tool

DESCRIPTION (provided by applicant): Functional magnetic resonance imaging (fMRI) is undeniably the neuroimaging methodology that has become the workhorse for neuroscience and psychology researchers who want access to localized measurements of physiological changes in the brain that correlate with human behavior. The high value of fMRI measurements is based on the fact that they have been shown, time and again, to exhibit a linear correlation with the local neural population response. There are, however, a recent smattering of articles in the literature indicating a mismatch between the fMRI response and the measured or presumed neural activity. These mismatches appear limited to experiments in which only a small neural population is stimulated; they also seem most likely to occur when the balance between local neural excitation and inhibition is tipped in favor of inhibition. These reports of fMRI responses that fail to correlate with neural responses are puzzling at best, and potentially troublesome for scientists who want to draw quantitative conclusions about neural population activity from fMRI data. Our first series of proposed experiments will characterize the effects of sampling resolution on the interpretability of the fMRI response to small stimuli. Not only do flanking negative responses confound accurate interpretation of the fMRI response to small patches of neural activity, because the boundary regions are large compared to the total neural response, but size-dependent intrinsic inhibition shapes the neural response yet has an unknown representation in the hemodynamic response. The result of the first series of experiments will be a computational model characterizing (1) neuro-hemodynamic coupling at the edges of isolated patches of neural activity, and (2) the contribution of inhibitory neural activity to the fMRI response. Our second series of experiments will characterize fMRI response evoked by neural networks with different balances between excitation and inhibition. All local neural codes contain a balance between input and output; local computations use a balance of excitation and inhibition to shape the input and define output spiking rates. In this series of experiments, we will investigate the implications of our recent study showing that localized fMRI of individual image patches cannot be predicted simply from the responses of the neurons that respond best to those stimuli. Working with a computational model that demonstrates how the entire local neural population response can be used to predict fMRI responses, this second series of experiments will seek to identify signature hemodynamic response characteristics that are present when heterogeneous neural responses mask key information encoded in a sub-population of neurons. Together, these experiments will improve our ability to use high-resolution fMRI to characterize patterned neural activity, improving the utility of fMRI for clinicl applications such as neurosurgical planning and seizure locus detection. PUBLIC HEALTH RELEVANCE: Scientists who study the brain need high-resolution imaging tools in order to understand how different patterns of neural activity correlate with different aspects of behavior; functional magnetic resonance imaging (fMRI) is one of the tools that can provide the highest imaging resolution. However, we still need to answer some fundamental questions about the relationship between the fMRI signal and the underlying neural activity in the brain. The work funded by this grant will develop more accurate models for linking neural activity patterns to fMRI responses when (1) the neural response occupies only a small portion of cortex, and (2) sub- populations of neurons right next to each other have different responses. This ability to detect activity or dysregulation of activity in a subpopulation of neurons is key fr high-resolution localization of neural function, for neurosurgical planning or seizure locus detection, as well as for quantifying biomarkers of diseases such as schizophrenia, which differentially affects inhibitory neurons in visual cortex.

描述(申请人提供)：不可否认，功能磁共振成像(FMRI)是一种神经成像方法，已成为神经科学和心理学研究人员的主力，他们希望获得与人类行为相关的大脑生理变化的局部测量。FMRI测量的高价值是基于这样一个事实，即它们一次又一次地被证明与局部神经群体反应呈线性相关。然而，最近文献中有零星的文章指出，功能磁共振反应与测量或推测的神经活动之间存在不匹配。这些错配似乎仅限于只有一小部分神经群体受到刺激的实验；当局部神经兴奋和抑制之间的平衡倾向于抑制时，它们似乎也最有可能发生。这些关于fMRI反应未能与神经反应相关的报告充其量是令人费解的，对于那些想要从fMRI数据中得出关于神经群体活动的定量结论的科学家来说，这可能会带来麻烦。我们提出的第一系列实验将表征采样分辨率对小刺激下fMRI反应的可解释性的影响。侧翼的负面反应不仅混淆了对小块神经活动的fMRI反应的准确解释，因为与总的神经反应相比，边界区域很大，而且大小依赖的内在抑制塑造了神经反应，但在血流动力学反应中具有未知的表现。第一系列实验的结果将是一个计算模型，其特征是(1)神经活动孤立斑块边缘的神经血流动力学耦合，以及(2)抑制神经活动对fMRI反应的贡献。我们的第二系列实验将表征由神经网络引起的fMRI反应，神经网络在兴奋和抑制之间具有不同的平衡。所有局部神经编码都包含输入和输出之间的平衡；局部计算使用激励和抑制的平衡来塑造输入和定义输出尖峰速率。在这一系列实验中，我们将调查我们最近的研究的含义，该研究表明，不能简单地根据对这些刺激反应最好的神经元的反应来预测单个图像块的局部fMRI。通过使用一个计算模型来演示如何使用整个局部神经群体反应来预测fMRI反应，第二系列实验将寻求识别当异质神经反应掩盖在神经元子群体中编码的关键信息时存在的标志性血流动力学反应特征。总之，这些实验将提高我们使用高分辨率功能磁共振成像来表征模式神经活动的能力，从而提高功能磁共振成像在临床应用中的实用性，如神经外科计划和癫痫发作部位检测。 与公共健康相关：研究大脑的科学家需要高分辨率的成像工具，以了解不同模式的神经活动如何与行为的不同方面相关；功能磁共振成像(FMRI)是能够提供最高成像分辨率的工具之一。然而，我们仍然需要回答一些关于fMRI信号和大脑潜在神经活动之间的关系的基本问题。这项由这笔赠款资助的工作将开发更准确的模型，将神经活动模式与功能磁共振反应联系起来，条件是(1)神经反应只占据大脑皮质的一小部分，(2)紧挨着的神经元亚群具有不同的反应。这种检测神经元亚群中活动或活动失调的能力是高分辨率定位神经功能的关键，对于神经外科计划或癫痫部位检测，以及对精神分裂症等疾病的生物标志物进行量化，这些疾病对视觉皮质中的抑制神经元产生不同的影响。