Zhang Yan, Wang Zuli, Cai Zhongzhou, Lin Qiang, Hu Zhenghui
College of Optical and Electronic Technology, China Jiliang University, Xueyuan Street 258, Hangzhou, 310018, China.
College of Optical Science and Engineering, Zhejiang University, Zheda Road 38, Hangzhou, 310027, China.
Biomed Eng Online. 2016 Feb 20;15:22. doi: 10.1186/s12938-016-0137-6.
The hemodynamic balloon model describes the change in coupling from underlying neural activity to observed blood oxygen level dependent (BOLD) response. It plays an increasing important role in brain research using magnetic resonance imaging (MRI) techniques. However, changes in the BOLD signal are sensitive to the resting blood volume fraction (i.e., [Formula: see text]) associated with the regional vasculature. In previous studies the value was arbitrarily set to a physiologically plausible value to circumvent the ill-posedness of the inverse problem. These approaches fail to explore actual [Formula: see text] value and could yield inaccurate model estimation.
The present study represents the first empiric attempt to derive the actual [Formula: see text] from data obtained using cerebral blood volume imaging, with the aim of augmenting the existing estimation schemes. Bimanual finger tapping experiments were performed to determine how [Formula: see text] influences the model estimation of BOLD signals within a single-region and multiple-regions (i.e., dynamic causal modeling). In order to show the significance of applying the true [Formula: see text], we have presented the different results obtained when using the real [Formula: see text] and assumed [Formula: see text] in terms of single-region model estimation and dynamic causal modeling.
The results show that [Formula: see text] significantly influences the estimation results within a single-region and multiple-regions. Using the actual [Formula: see text] might yield more realistic and physiologically meaningful model estimation results.
Incorporating regional venous information in the analysis of the hemodynamic model can provide more reliable and accurate parameter estimations and model predictions, and improve the inference about brain connectivity based on fMRI data.
血液动力学气球模型描述了从潜在神经活动到观察到的血氧水平依赖（BOLD）反应的耦合变化。它在使用磁共振成像（MRI）技术的脑研究中发挥着越来越重要的作用。然而，BOLD信号的变化对与局部脉管系统相关的静息血容量分数（即，[公式：见正文]）敏感。在先前的研究中，该值被任意设定为一个生理上合理的值，以规避反问题的不适定性。这些方法未能探索实际的[公式：见正文]值，可能会产生不准确的模型估计。
本研究首次尝试从使用脑血容量成像获得的数据中推导实际的[公式：见正文]，目的是增强现有的估计方案。进行了双手手指敲击实验，以确定[公式：见正文]如何影响单区域和多区域内BOLD信号的模型估计（即动态因果建模）。为了显示应用真实[公式：见正文]的重要性，我们展示了在单区域模型估计和动态因果建模中使用真实[公式：见正文]和假设[公式：见正文]时获得的不同结果。
结果表明，[公式：见正文]显著影响单区域和多区域内的估计结果。使用实际的[公式：见正文]可能会产生更现实和生理上有意义的模型估计结果。
在血液动力学模型分析中纳入局部静脉信息可以提供更可靠和准确的参数估计和模型预测，并改善基于功能磁共振成像数据对脑连接性的推断。
