V1 is not uniquely identified by polarity reversals of responses to upper and lower visual field stimuli.
V1 is not uniquely identified by polarity reversals of responses to upper and lower visual field stimuli.
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DOI：
10.1016/j.neuroimage.2010.05.016
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发表时间：
2010-10-01
期刊：
影响因子：
5.7
通讯作者：
Norcia, Anthony M.
中科院分区：
文献类型：
--
作者：
Ales, Justin M.;Yates, Jacob L.;Norcia, Anthony M.
十字形假说指出，如果视觉诱发电位成分起源于 V1，那么置于上视野和下视野的刺激将在头皮处产生相反极性的反应。该诊断已被许多研究用作 V1 来源的明确标记。为了对十字形假设的有效性进行实证检验，我们生成了皮质区域 V1、V2 和 V3 的正向模型，这些模型基于对这些区域的 3D 形状以及大脑、头骨和头皮的形状和电导率的实际估计。功能性 MRI 用于识别早期视觉区域的位置，解剖 MRI 数据用于构建详细的皮质表面重建，并生成每个参与者头部电导率的边界元方法正演模型。每个受试者的这两个数据集用于从每个视觉区域的背侧和腹侧细分生成模拟头皮活动，分别对应于下视野和上视野表示。预测的拓扑显示 V1 中的源并不完全符合十字形符号反转。此外，与模型相反，视网膜专题视觉区域 V2 和 V3 显示上场和下场刺激的极性反转。因此，上场刺激与下场刺激的响应极性反转的存在不足以识别源自 V1 的响应。
The cruciform hypothesis states that if a visual evoked potential component originates in V1, then stimuli placed in the upper versus lower visual fields will generate responses with opposite polarity at the scalp. This diagnostic has been used by many studies as a definitive marker of V1 sources. To provide an empirical test of the validity of the cruciform hypothesis, we generated forward models of cortical areas V1, V2 and V3 that were based on realistic estimates of the 3-D shape of these areas and the shape and conductivity of the brain, skull and scalp. Functional MRI was used to identify the location of early visual areas and anatomical MRI data was used construct detailed cortical surface reconstructions and to generate boundary element method forward models of the electrical conductivity of each participant’s head. These two data sets for each subject were used to generate simulated scalp activity from the dorsal and ventral subdivisions of each visual area that correspond to the lower and upper visual field representations, respectively. The predicted topographies show that sources in V1 do not fully conform to the cruciform sign-reversal. Moreover, contrary to the model, retinotopic visual areas V2 and V3 show polarity reversals for upper and lower field stimuli. The presence of a response polarity inversion for upper versus lower field stimuli is therefore an insufficient criterion for identifying responses as having originated in V1.
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