Field potentials (FPs) reflect neuronal activities in the brain, and often exhibit traveling peaks across recording sites. While traveling FPs are interpreted as propagation of neuronal activity, not all studies directly reveal such propagating patterns of neuronal activation. Neuronal activity is associated with transmembrane currents that form dipoles and produce negative and positive fields. Thereby, FP components reverse polarity between those fields and have minimal amplitudes at the center of dipoles. Although their amplitudes could be smaller, FPs are never flat even around these reversals. What occurs around the reversal has not been addressed explicitly, although those are rationally in the middle of active neurons. We show that sensory FPs around the reversal appeared with peaks traveling across cortical laminae in macaque sensory cortices. Interestingly, analyses of current source density did not depict traveling patterns but lamina-delimited current sinks and sources. We simulated FPs produced by volume conduction of a simplified 2 dipoles' model mimicking sensory cortical laminar current source density components. While FPs generated by single dipoles followed the temporal patterns of the dipole moments without traveling peaks, FPs generated by concurrently active dipole moments appeared with traveling components in the vicinity of dipoles by superimposition of individually non-traveling FPs generated by single dipoles. These results indicate that not all traveling FP are generated by traveling neuronal activity, and that recording positions need to be taken into account to describe FP peak components around active neuronal populations.

SIGNIFICANCE STATEMENT Field potentials (FPs) generated by neuronal activity in the brain occur with fields of opposite polarity. Likewise, in the cerebral cortices, they have mirror-imaged waveforms in upper and lower layers. We show that FPs appear like traveling across the cortical layers. Interestingly, the traveling FPs occur without traveling components of current source density, which represents transmembrane currents associated with neuronal activity. These seemingly odd findings are explained using current source density models of multiple dipoles. Concurrently active, non-traveling dipoles produce FPs as mixtures of FPs produced by individual dipoles, and result in traveling FP waveforms as the mixing ratio depends on the distances from those dipoles. The results suggest that not all traveling FP components are associated with propagating neuronal activity.

场电位 (FP) 反映了大脑中的神经元活动，并且通常会在记录站点之间显示出移动峰值。虽然旅行 FP 被解释为神经元活动的传播，但并非所有研究都直接揭示了神经元激活的这种传播模式。神经元活动与形成偶极子并产生负场和正场的跨膜电流有关。因此，FP 分量在这些场之间反转极性，并且在偶极子的中心具有最小的幅度。尽管它们的振幅可能更小，但即使在这些反转附近，FP 也永远不会平坦。围绕逆转发生的事情还没有得到明确的解决，尽管这些都是理性的处于活跃神经元的中间。我们表明，反转周围的感觉 FP 出现在猕猴感觉皮层中穿过皮层板的峰值。有趣的是，对电流源密度的分析并未描绘行进模式，而是描绘了以薄片为界的电流汇和源。我们模拟了由模拟感觉皮层层流电流源密度分量的简化 2 偶极子模型的体积传导产生的 FP。虽然由单偶极子产生的 FP 遵循偶极矩的时间模式而没有传播峰值，但由同时活动的偶极矩产生的 FP 通过叠加由单个偶极子产生的单独非传播 FP 在偶极子附近出现了传播分量。这些结果表明，并非所有旅行 FP 都是由旅行神经元活动产生的，

意义声明由大脑中的神经元活动产生的场电位 (FP) 出现在相反极性的场中。同样，在大脑皮质中，它们在上层和下层具有镜像波形。我们展示了 FP 看起来像是穿过皮质层。有趣的是，移动的 FP 没有电流源密度的移动分量发生，电流源密度代表与神经元活动相关的跨膜电流。这些看似奇怪的发现可以使用多个偶极子的电流源密度模型来解释。同时活动的非行进偶极子将 FP 作为单个偶极子产生的 FP 的混合物产生，并导致行进的 FP 波形，因为混合比取决于与这些偶极子的距离。结果表明，并非所有旅行 FP 组件都与传播神经元活动相关。