Exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials.
Exploiting individual primary visual cortex geometry to boost steady state visual evoked potentials.
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DOI：
10.1088/1741-2560/10/3/036003
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发表时间：
2013-06
影响因子：
4
通讯作者：
Kelly SP
中科院分区：
文献类型：
--
作者：
Vanegas MI;Blangero A;Kelly SP
稳态视觉诱发电位（SSVEP）是部分在初级视觉区V1产生的闪烁刺激的脑电图反应。典型的“十字形”几何形状和视网膜组织是这样的，某些相邻的视觉区域投射到相邻的相反方向的皮质区域。在这里，我们探索了利用这种组织通过振荡求和来提高头皮SSVEP振幅的方法。我们以三种方式操纵大环形刺激的角段之间的闪烁相位偏移，并将产生的SSVEP功率与没有时间相位偏移的常规条件进行比较。1)我们将所有被试的圆环划分为标准八进制，上下八进制的时间相位与上下八进制相反，上下八进制的时间相位与上下八进制的时间相位相反；2)我们分别调整了标准八边形条件下8个相邻片段之间的边界，使其与32个等大小片段的模式脉冲多焦点视觉诱发电位（PPMVEP）的十字形一致的早潜伏期地形变化相一致；3)基于垂直方向和水平方向的PPMVEP分量的相对振幅，采用自动算法为刺激段分配相位偏移。三种闪烁相位操作使归一化SSVEP功率分别显著提高了1)202%、2)383%和3)300%。因此，我们已经证明了一种方法来获得更可靠的测量视觉诱发活动纯粹通过考虑皮质几何。这一原则将影响使用ssvep的基础和临床研究。
The steady-state visual evoked potential (SSVEP) is an electroencephalographic response to flickering stimuli generated partly in primary visual area V1. The typical “cruciform” geometry and retinotopic organization of V1 is such that certain neighboring visual regions project to neighboring cortical regions of opposite orientation. Here, we explored ways to exploit this organization in order to boost scalp SSVEP amplitude via oscillatory summation. We manipulated flicker-phase offsets among angular segments of a large annular stimulus in three ways, and compared the resultant SSVEP power to a conventional condition with no temporal phase offsets. 1) we divided the annulus into standard octants for all subjects, and flickered upper horizontal octants with opposite temporal phase to the lower horizontal ones, and left vertical octants opposite to the right vertical ones; 2) we individually adjusted the boundaries between the 8 contiguous segments of the standard octants condition to coincide with cruciform-consistent, early-latency topographical shifts in pattern-pulse multifocal visual-evoked potentials (PPMVEP) derived for each of 32 equal-sized segments; 3) we assigned phase offsets to stimulus segments following an automatic algorithm based on the relative amplitudes of vertically- and horizontally-oriented PPMVEP components. The three flicker-phase manipulations resulted in a significant enhancement of normalized SSVEP power of 1) 202%, 2) 383%, and 3) 300%, respectively. We have thus demonstrated a means to obtain more reliable measures of visual evoked activity purely through consideration of cortical geometry. This principle stands to impact both basic and clinical research using SSVEPs.
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DOI：
10.1016/0168-5597(87)90046-3
发表时间：
1987-07-01
期刊：
ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY
影响因子：
--
作者：
BUTLER, SR;GEORGIOU, GA;SMITH, KRH
通讯作者：
SMITH, KRH
影响因子：
5.7
作者：
Ales, Justin M.;Yates, Jacob L.;Norcia, Anthony M.
通讯作者：
Norcia, Anthony M.
影响因子：
64.8
作者：
Müller, MM;Malinowski, P;Hillyard, SA
通讯作者：
Hillyard, SA
影响因子：
--
作者：
Pelli, DG
通讯作者：
Pelli, DG
影响因子：
4.4
作者：
James, AC
通讯作者：
James, AC