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首页> 外文会议>日本応用磁気学会学術講演会 >Matching of visual patterns in the human brain revealed by MEG.
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Matching of visual patterns in the human brain revealed by MEG.

机译：梅格透露人类大脑中的视觉模式匹配。

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Multichannel whole-head magnetoencephalography (MEG) represents a powerful noninvasive tool for source estimation and elucidation of dynamics of brain activity during performance of different working memory tasks. In the present study we aimed to evaluate the possible magnetoencephalographic correlates of human brain activity during matching working memory processes of visual patterns. Multichannel magnetoencephalogram was recorded from human subjects as they were performing a delay-match to-sample task with colored visual patterns. Each trial consisted in the presentation of a sample visual pattern for 500ms. After an interval of 3.5 seconds a test stimulus was presented for comparison. The subjects were instructed to react after decision with button press when a third stimulus (mark) was presented 1.5 s later. To obtain a reliable baseline an interval of 3 s was used between the presentation of the mark and the next trial. Besides this memory task the same sequence was used in control condition for comparisons between the data (subjects were instructed to press a button after the mark without trying to memorize the sample). Magnetic data were acquired using a 204-channel whole-head SQUID gradiometer device. On-line averaging was used to obtain the averaged visual event-related magnetic fields (ERFs) for two conditions related to test stimuli onset: memory and control. Eye blink activity was monitored. Averaged magnetic data were digitally filtered to a 0.5-45 Hz frequency band. About 50-100 trials were averaged and analyzed for both conditions. We compared the obtained ERF data between two conditions (after the presentation of the test stimuli: in memory condition the subjects were required to compare the test stimulus with the previously memorized sample, in control condition on the other hand to simply attend the same sequence without performing any matching between the presented visual patterns). Analysis of the data consisted in comparison of ERFs waveforms between two conditions, observation of changes in magnetic flux or gradient maps across time, and further source estimation using parametric dipolar fitting procedures and minimum-norm estimates of current density in the brain.
机译：多通道全头脑磁图（MEG）表示源估计和大脑活动的动态阐释的不同的工作记忆任务执行过程中一个强大的非侵入性的工具。在本研究中，我们的目的相匹配的视觉模式的工作记忆过程中评估人类大脑活动的可能magnetoencephalographic相关因素。多通道脑磁图从人类受试者，因为他们具有彩色视觉模式进行延迟匹配样本任务记录。每个试验包括在500毫秒的样本的视觉图案的呈现。的间隔为3.5秒后的测试刺激呈现以供比较。受试者被指示当第三刺激（标记）被稍后给出1.5秒决定后反应以按下按钮。为了得到可靠的基线标记的介绍和接下来的试验之间使用的3秒的时间间隔。除此之外记忆任务在控制条件被用于数据之间的比较相同的序列（指示受试者按下标记后一个按钮而不试图记住的样品）。磁数据使用一个204通道全头SQUID梯度计装置获取。上线平均用于获得针对与测试激励发病两个条件平均视觉事件相关的磁场（ERFS）：存储器和控制。眨眼活动进行监控。平均磁数据进行数字滤波，以一个0.5-45赫兹频带。约50-100试验的平均值，这两种情况进行分析。我们比较两个条件之间所获得的ERF数据（测试刺激的呈现之后：在存储器中的条件的受试者被要求以比较与先前存储的样品的测试激励，在控制条件，另一方面，以简单地参加没有相同序列执行所述呈现的视觉图案之间的任何匹配）。数据的分析包括在两个条件，使用参数偶极拟合程序和在脑中的电流密度的最小范数的估计的磁通或跨越时间梯度图，并进一步源估计的变化的观察之间ERF​​S波形的比较。

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