Klistorner A, Crewther D P, Crewther S G
School of Optometry, University of New South Wales, Sydney, Australia.
Vision Res. 1997 Aug;37(15):2161-9. doi: 10.1016/s0042-6989(97)00003-5.
Temporal analysis of the multifocal cortical visual evoked potential (VEP) was studied using pseudo-random (m-sequence) achromatic stimulation. The effects of variation of luminance contrast on the first-order response were complex. At low to mid contrasts (< 60%), a wave doublet (P100-N115) predominated. A second wave complex (N100-P120-N160) dominated at high contrasts. The second-order responses, however, showed an extremely simple variation with luminance contrast. Intrinsic differences in the adaptation time of the generators of these two components caused a distinct separation in the slices of the second-order response. A rapidly adapting nonlinearity saturating at low contrasts was only observable when measuring the responses from two consecutive flashes. Its latency coincided with the contrast saturating first-order response component. By comparison, the nonlinearity derived from the responses to the stimuli with longer interstimulus intervals (second and third slices) yielded a much more linear contrast response function with lower contrast gain and latencies, which clearly corresponded to the longer latency component of the first-order response. Thus, the second-order responses show a first slice which is predominantly driven by neural elements that have a latency and contrast function that mimic those of the magnocellular neurons of the primate LGN and a second slice which is dominated by a generator whose properties resemble primate parvocellular function. This division into magno and parvocellular contribution to the VEP is based on function (interaction time) as distinct from other currently available analyses, with potential for neural analysis of visual disease.
利用伪随机（m序列）消色差刺激研究了多焦点皮层视觉诱发电位（VEP）的时间分析。亮度对比度变化对一级反应的影响很复杂。在低到中等对比度（<60%）时，一个波双峰（P100-N115）占主导。在高对比度时，第二个波复合体（N100-P120-N160）占主导。然而，二级反应随亮度对比度呈现出极其简单的变化。这两个成分的发生器适应时间的内在差异导致了二级反应切片中的明显分离。只有在测量两个连续闪光的反应时，才能观察到在低对比度下饱和的快速适应非线性。其潜伏期与对比度饱和的一级反应成分一致。相比之下，从较长刺激间隔（第二和第三切片）的刺激反应中得出的非线性产生了一个对比度增益和潜伏期较低的更线性的对比度反应函数，这明显对应于一级反应中潜伏期较长的成分。因此，二级反应显示出第一个切片主要由潜伏期和对比度功能类似于灵长类动物外侧膝状体大细胞神经元的神经元件驱动，第二个切片则由特性类似于灵长类动物小细胞功能的发生器主导。这种对VEP的大细胞和小细胞贡献的划分是基于功能（相互作用时间），与目前其他可用分析不同，具有对视觉疾病进行神经分析的潜力。
