Department of Neurobiology and the Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, Connecticut, USA.
J Neurophysiol. 2010 Feb;103(2):677-97. doi: 10.1152/jn.90946.2008. Epub 2009 Nov 11.
The aim of the present study was to characterize the spatial and temporal features of synaptic and discharge receptive fields (RFs), and to quantify their relationships, in cat area 17. For this purpose, neurons were recorded intracellularly while high-frequency flashing bars were used to generate RFs maps for synaptic and spiking responses. Comparison of the maps shows that some features of the discharge RFs depended strongly on those of the synaptic RFs, whereas others were less dependent. Spiking RF duration depended poorly and spiking RF amplitude depended moderately on those of the underlying synaptic RFs. At the other extreme, the optimal spatial frequency and phase of the discharge RFs in simple cells were almost entirely inherited from those of the synaptic RFs. Subfield width, in both simple and complex cells, was less for spiking responses compared with synaptic responses, but synaptic to discharge width ratio was relatively variable from cell to cell. When considering the whole RF of simple cells, additional variability in width ratio resulted from the presence of additional synaptic subfields that remained subthreshold. Due to these additional, subthreshold subfields, spatial frequency tuning predicted from synaptic RFs appears sharper than that predicted from spiking RFs. Excitatory subfield overlap in spiking RFs was well predicted by subfield overlap at the synaptic level. When examined in different regions of the RF, latencies appeared to be quite variable, but this variability showed negligible dependence on distance from the RF center. Nevertheless, spiking response latency faithfully reflected synaptic response latency.
本研究旨在描述猫大脑 17 区突触和放电感受野 (RF) 的时空特征，并量化它们之间的关系。为此，我们在细胞内记录神经元，同时使用高频闪烁条生成突触和放电反应的 RF 图。对这些图的比较表明，放电 RF 的某些特征强烈依赖于突触 RF，而其他特征则较少依赖。放电 RF 的持续时间和幅度与潜在的突触 RF 相关程度较差和中等。在另一方面，简单细胞的放电 RF 的最佳空间频率和相位几乎完全来自于突触 RF。在简单和复杂细胞中，与突触反应相比，放电反应的子场宽度较小，但突触到放电宽度比在细胞间变化较大。当考虑简单细胞的整个 RF 时，宽度比的额外可变性源于存在保持亚阈值的额外突触子场。由于这些额外的、亚阈值的子场，从突触 RF 预测的空间频率调谐似乎比从放电 RF 预测的更尖锐。在放电 RF 中兴奋性子场重叠很好地预测了突触水平上的子场重叠。在 RF 的不同区域进行检查时，潜伏期似乎相当可变，但这种可变性与距 RF 中心的距离几乎没有关系。尽管如此，放电反应潜伏期忠实地反映了突触反应潜伏期。
