Controlling an avatar by thought using real-time fMRI
Controlling an avatar by thought using real-time fMRI
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DOI：
10.1088/1741-2560/11/3/035006
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发表时间：
2014-06-01
影响因子：
4
通讯作者：
Friedman, Doron
中科院分区：
文献类型：
--
作者：
Cohen, Ori;Koppel, Moshe;Friedman, Doron
客观的。我们开发了一种基于具有虚拟现实反馈的实时功能磁共振成像（fMRI）的脑机接口（BCI）系统。 fMRI的优点是空间分辨率相对较高，覆盖全脑；因此，我们期望它可以用于探索基于新型心理活动的新颖的 BCI 策略。然而，fMRI 存在时间分辨率低和固有延迟的问题，因为它基于血流动力学响应而不是电信号。因此，我们本文的目标是探索受试者是否可以使用我们的系统在虚拟环境中执行 BCI 任务，以及延迟如何影响他们的表现。方法。受试者通过左手、右手和腿部运动或图像来控制化身。 BCI 分类基于定位与每个运动类别相关的感兴趣区域 (ROI)，并在线选择具有最大平均值的 ROI。受试者执行基于提示的任务和自由选择任务，分析包括对表现的评估以及主观报告。主要结果。当允许移动手指和脚趾时，六名受试者以高精度完成了任务，三名受试者仅使用图像就获得了高精度。在基于提示的任务中，触发后 8-12 秒的准确度最高，而在自由选择任务中，当触发后 6 秒提供反馈时，受试者表现最佳。意义。我们证明，尽管存在血流动力学延迟，受试者仍能够使用基于功能磁共振成像的脑机接口在虚拟环境中执行导航任务。同样的方法可以扩展到其他心理任务和其他大脑区域。
Objective. We have developed a brain-computer interface (BCI) system based on real-time functional magnetic resonance imaging (fMRI) with virtual reality feedback. The advantage of fMRI is the relatively high spatial resolution and the coverage of the whole brain; thus we expect that it may be used to explore novel BCI strategies, based on new types of mental activities. However, fMRI suffers from a low temporal resolution and an inherent delay, since it is based on a hemodynamic response rather than electrical signals. Thus, our objective in this paper was to explore whether subjects could perform a BCI task in a virtual environment using our system, and how their performance was affected by the delay. Approach. The subjects controlled an avatar by left-hand, right-hand and leg motion or imagery. The BCI classification is based on locating the regions of interest (ROIs) related with each of the motor classes, and selecting the ROI with maximum average values online. The subjects performed a cue-based task and a free-choice task, and the analysis includes evaluation of the performance as well as subjective reports. Main results. Six subjects performed the task with high accuracy when allowed to move their fingers and toes, and three subjects achieved high accuracy using imagery alone. In the cue-based task the accuracy was highest 8-12 s after the trigger, whereas in the free-choice task the subjects performed best when the feedback was provided 6 s after the trigger. Significance. We show that subjects are able to perform a navigation task in a virtual environment using an fMRI-based BCI, despite the hemodynamic delay. The same approach can be extended to other mental tasks and other brain areas.