McKeefry D J
Vision Science Research Group, School of Biomedical Sciences, University of Ulster, Coleraine, N. Ireland, BT52 1SA, UK.
Vision Res. 2002 Mar;42(7):909-22. doi: 10.1016/s0042-6989(02)00024-x.
Motion-onset visual evoked potentials (VEPs) were elicited by low spatial frequency chromatic isoluminant gratings presented in a central 7 degrees circular field. The chromatic composition of the stimuli was varied so as to modulate along different axes in colour space. For slow speeds (<5 degrees/s) changing the chromatic axis induced large response differences between the S- and L/M-cone VEPs. At faster speeds (5-12 degrees/s) the effects were not as marked. A dichotomy between the slow and fast responses was also shown to exist in terms of their contrast dependencies, the former exhibiting a stronger dependency on contrast than the latter. These findings suggest that neural substrates with chromatic sensitivity are involved in the generation of S- and L/M-cone mediated motion-onset VEPs at low velocities. At higher velocities, responses are generated by different mechanisms that possess little or no chromatic sensitivity.
运动起始视觉诱发电位（VEPs）由呈现于中央7度圆形视野的低空间频率等亮度彩色光栅诱发。刺激的色彩构成不断变化，以便在颜色空间中沿不同轴进行调制。对于低速（<5度/秒）而言，改变色轴会在S-和L/M-视锥细胞VEPs之间引起较大的反应差异。在较高速度（5-12度/秒）时，这种效应并不那么明显。慢反应和快反应在对比度依赖性方面也存在二分法，前者比后者表现出更强的对比度依赖性。这些发现表明，具有颜色敏感性的神经基质在低速时参与了S-和L/M-视锥细胞介导的运动起始VEPs的产生。在较高速度下，反应由几乎没有或没有颜色敏感性的不同机制产生。
