Cao Jianwei, Wang Xinlong, Liu Hanli, Alexandrakis George
University of Texas at Arlington & University of Texas Southwestern Medical Center at Dallas, Joint Graduate Program in Biomedical Engineering, Arlington, Texas 76010.
Biomed Opt Express. 2018 Oct 10;9(11):5296-5317. doi: 10.1364/BOE.9.005296. eCollection 2018 Nov 1.
Little work has been done on the information flow in functional brain imaging and none so far in fNIRS. In this work, alterations in the directionality of net information flow induced by a short-duration, low-current (2 min 40 s; 0.5 mA) and a longer-duration, high-current (8 min; 1 mA) anodal tDCS applied over the Broca's area of the dominant language hemisphere were studied by fNIRS. The tDCS-induced patterns of information flow, quantified by a novel directed phase transfer entropy (dPTE) analysis, were distinct for different hemodynamic frequency bands and were qualitatively similar between low and high-current tDCS. In the endothelial band (0.003-0.02 Hz), the stimulated Broca's area became the strongest hub of outgoing information flow, whereas in the neurogenic band (0.02-0.04 Hz) the contralateral homologous area became the strongest information outflow source. In the myogenic band (0.04-0.15 Hz), only global patterns were seen, independent of tDCS stimulation that were interpreted as Mayer waves. These findings showcase dPTE analysis in fNIRS as a novel, complementary tool for studying cortical activity reorganization after an intervention.
关于功能脑成像中的信息流研究较少，而近红外光谱技术（fNIRS）方面目前尚无相关研究。在本研究中，我们通过fNIRS研究了在优势语言半球的布洛卡区施加短时间、低电流（2分40秒；0.5毫安）和长时间、高电流（8分钟；1毫安）阳极经颅直流电刺激（tDCS）所引起的净信息流方向性变化。通过一种新型的定向相位转移熵（dPTE）分析对tDCS诱导的信息流模式进行量化，结果表明，不同血液动力学频段的信息流模式各异，且低电流和高电流tDCS之间在性质上相似。在内皮频段（0.003 - 0.02赫兹），受刺激的布洛卡区成为最强的传出信息流枢纽，而在神经源性频段（0.02 - 0.04赫兹），对侧同源区域成为最强的信息流出源。在肌源性频段（0.04 - 0.15赫兹），仅观察到整体模式，且与tDCS刺激无关，这些模式被解释为迈尔波。这些发现表明，fNIRS中的dPTE分析是一种用于研究干预后皮质活动重组的新型补充工具。
