Laboratory of Psychophysiology, Faculdade da Saúde, UMESP, São Paulo, SP, Brazil.
Division of Neurosurgery, Department of Neurology, University of São Paulo Medical School, São Paulo, SP, Brazil.
Neurol Sci. 2021 Sep;42(9):3781-3789. doi: 10.1007/s10072-021-05062-z. Epub 2021 Jan 16.
Average slow potentials (SPs) can be computed from any voluntary task, minimally involving attention to anticipated stimuli. Their topography when recorded by large electrode arrays even during simple tasks is complex, multifocal, and its generators appear to be equally multifocal and highly variable across subjects. Various sources of noise of course contaminate such averages and must contribute to the topographic complexity. Here, we report a study in which the non-averaged SP band (0 to 1 Hz) was analyzed by independent components (ICA), from 256 channel recordings of 18 subjects, during four task conditions (resting, visual attention, CPT, and Stroop). We intended to verify whether the replicable SP generators (between two separate day sessions) modeled as current density reconstruction on structural MRI sets were individual-specific, and if putative task-related differences were systematic across subjects. Typically, 3 ICA components (out of 10) explained SPs in each task and subject, and their combined generators were highly variable across subjects: although some occipito-temporal and medial temporal areas contained generators in most subjects; the overall patterns were obviously variable, with no single area common to all 18 subjects. Linear regression modeling to compare combined generators (from all ICA components) between tasks and sessions showed significantly higher correlations between the four tasks than between sessions for each task. Moreover, it was clear that no common task-specific areas could be seen across subjects. Those results represent one more instance in which individual case analyses favor the hypothesis of individual-specific patterns of cortical activity, regardless of task conditions. We discuss this hypothesis with respect to results from the beta band, from individual-case fMRI studies, and its corroboration by functional neurosurgery and the neuropsychology of focal lesions.
平均慢电位 (SP) 可通过任何涉及预期刺激的注意力最小的自愿任务计算得出。即使在执行简单任务时，使用大型电极阵列记录时，其地形图也很复杂，具有多焦点性，其发生器似乎也具有同样的多焦点性，并且在不同的受试者之间差异很大。当然，各种噪声源会污染此类平均值，并且必须对地形复杂性做出贡献。在这里，我们报告了一项研究，该研究在 18 位受试者的 256 通道记录中，对非平均 SP 带（0 至 1 Hz）进行了独立成分（ICA）分析，实验涉及四个任务条件（休息、视觉注意、CPT 和 Stroop）。我们旨在验证可复制的 SP 发生器（在两个单独的日间会议之间）是否建模为结构 MRI 集上的电流密度重建是个体特异性的，并且如果存在与任务相关的差异，是否在所有受试者中都是系统的。通常，每个任务和每个受试者中的 3 个 ICA 分量（共 10 个）可以解释 SP，并且它们的组合发生器在受试者之间变化很大：尽管大多数受试者的枕颞和内侧颞区都包含发生器；但是整体模式显然是可变的，没有一个区域是所有 18 个受试者共有的。用于比较任务和会话之间的组合发生器（来自所有 ICA 分量）的线性回归建模表明，与每个任务的会话相比，四个任务之间的相关性明显更高。此外，显然不能在所有受试者中看到共同的特定任务区域。这些结果再次证明了个体案例分析支持皮质活动的个体特异性模式的假设，而与任务条件无关。我们根据β频带、个体病例 fMRI 研究以及功能神经外科和局灶性病变神经心理学的结果，对该假设进行了讨论。
