Laboratory of Psychophysiology, Faculdade da Saúde, UMESP, São Paulo, Brazil.
PLoS One. 2013;8(3):e59595. doi: 10.1371/journal.pone.0059595. Epub 2013 Mar 27.
Based on previous evidence for individual-specific sets of cortical areas active during simple attention tasks, in this work we intended to perform within individual comparisons of task-induced beta oscillations between visual attention and a reasoning task. Since beta induced oscillations are not time-locked to task events and were first observed by Fourier transforms, in order to analyze the cortical topography of attention induced beta activity, we have previously computed corrected-latency averages based on spontaneous peaks of band-pass filtered epochs. We then used Independent Component Analysis (ICA) only to single out the significant portion of averaged data, above noise levels. In the present work ICA served as the main, exhaustive means for decomposing beta activity in both tasks, using 128-channel EEG data from 24 subjects. Given the previous observed similarity between tasks by visual inspection and by simple descriptive statistics, we now intended another approach: to quantify how much each ICA component obtained in one task could be explained by a linear combination of the topographic patterns from the other task in each individual. Our hypothesis was that the major psychological difference between tasks would not be reflected as important topographic differences within individuals. Results confirmed the high topographic similarity between attention and reasoning beta correlates in that few components in each individual were not satisfactorily explained by the complementary task, and if those could be considered "task-specific", their scalp distribution and estimated cortical sources were not common across subjects. These findings, along with those from fMRI studies preserving individual data and conventional neuropsychological and neurosurgical observations, are discussed in support of a new functional localization hypothesis: individuals use largely different sets of cortical association areas to perform a given task, but those individual sets do not change importantly across tasks that differ in major psychological processes.
基于先前关于在简单注意任务中活跃的个体特定皮质区域集的证据，在这项工作中，我们旨在对视觉注意和推理任务之间的任务诱导β振荡进行个体内比较。由于β诱导的振荡与任务事件没有时间锁定，并且首先通过傅里叶变换观察到，为了分析注意诱导β活动的皮质拓扑结构，我们之前已经根据带通滤波的自发峰值计算了校正后的潜伏期平均值。然后，我们仅使用独立成分分析（ICA）来分离出平均数据中高于噪声水平的显著部分。在目前的工作中，ICA 是分解两个任务中β活动的主要、详尽手段，使用来自 24 个受试者的 128 通道 EEG 数据。鉴于先前通过视觉检查和简单描述性统计观察到任务之间的相似性，我们现在采用了另一种方法：量化在一个任务中获得的每个 ICA 分量在每个个体中如何通过另一个任务的地形模式的线性组合来解释。我们的假设是，任务之间的主要心理差异不会反映为个体内部的重要地形差异。结果证实了注意力和推理β相关物之间的高度地形相似性，因为在每个个体中，很少有分量不能通过互补任务得到满意的解释，如果这些可以被认为是“任务特异性”的，那么它们的头皮分布和估计的皮质源在个体之间并不常见。这些发现，以及那些保留个体数据的 fMRI 研究和传统神经心理学和神经外科观察的发现，支持了一种新的功能定位假说：个体使用大量不同的皮质联合区域来执行给定的任务，但这些个体区域在主要心理过程不同的任务中不会发生重要变化。
