Cognitive Neuroscience and Schizophrenia Program, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York; and
Cognitive Neuroscience and Schizophrenia Program, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York; and Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York.
J Neurophysiol. 2015 Jan 1;113(1):339-51. doi: 10.1152/jn.00914.2013. Epub 2014 Oct 1.
Field potentials (FPs) recorded within the brain, often called "local field potentials" (LFPs), are useful measures of net synaptic activity in a neuronal ensemble. However, due to volume conduction, FPs spread beyond regions of underlying synaptic activity, and thus an "LFP" signal may not accurately reflect the temporal patterns of synaptic activity in the immediately surrounding neuron population. To better understand the physiological processes reflected in FPs, we explored the relationship between the FP and its membrane current generators using current source density (CSD) analysis in conjunction with a volume conductor model. The model provides a quantitative description of the spatiotemporal summation of immediate local and more distant membrane currents to produce the FP. By applying the model to FPs in the macaque auditory cortex, we have investigated a critical issue that has broad implications for FP research. We have shown that FP responses in particular cortical layers are differentially susceptible to activity in other layers. Activity in the supragranular layers has the strongest contribution to FPs in other cortical layers, and infragranular FPs are most susceptible to contributions from other layers. To define the physiological processes generating FPs recorded in loci of relatively weak synaptic activity, strong effects produced by synaptic events in the vicinity have to be taken into account. While outlining limitations and caveats inherent to FP measurements, our results also suggest specific peak and frequency band components of FPs can be related to activity in specific cortical layers. These results may help improving the interpretability of FPs.
脑内记录的场电位（FPs），通常称为“局部场电位”（LFPs），是神经元集合中净突触活动的有用测量指标。然而，由于容积传导，FPs 会扩散到潜在突触活动区域之外，因此“LFP”信号可能无法准确反映周围神经元群体中突触活动的时间模式。为了更好地理解 FPs 所反映的生理过程，我们使用电流源密度（CSD）分析结合容积导体模型，探索了 FP 与其膜电流发生器之间的关系。该模型提供了对即时局部和更远距离的膜电流进行时空总和以产生 FP 的定量描述。通过将模型应用于猕猴听觉皮层中的 FPs，我们研究了一个对 FP 研究具有广泛影响的关键问题。我们已经表明，特定皮层层的 FP 反应对其他层的活动具有不同的敏感性。在颗粒上层的活动对其他皮层层的 FP 有最强的贡献，而颗粒下层的 FP 最容易受到其他层的贡献。为了定义在相对较弱的突触活动位置记录的 FPs 所产生的生理过程，必须考虑附近突触事件产生的强烈影响。虽然概述了 FP 测量固有的局限性和注意事项，但我们的结果还表明，FPs 的特定峰值和频带分量可以与特定皮层层的活动相关。这些结果可能有助于提高 FPs 的可解释性。
