McGovern David P, Peirce Jonathan W
Nottingham Visual Neuroscience, School of Psychology, University of Nottingham, Nottingham NG7 2RD, UK.
Vision Res. 2010 Apr 7;50(8):796-804. doi: 10.1016/j.visres.2010.01.018. Epub 2010 Feb 1.
Rather little is known about the mechanisms that combine the outputs of orientation- and spatial frequency-selective channels. These can be studied by measuring the selective adaptation to compound stimuli over and above that expected from adaptation to the components alone (Peirce & Taylor, 2006). Here we investigated the contrast- and spatial phase-dependency of such mechanisms. A plaid was adapted in one visual hemi-field, while its constituent gratings were simultaneously adapted in the other hemi-field. Plaid-selective adaptation was most apparent with high-contrast probes, whereas adaptation to the component grating stimuli dominated at low contrasts. The mechanisms underlying this plaid-selective adaptation also appear to be insensitive to the spatial phase of the probes relative to the adaptor, whereas we find a clear phase-dependency for suprathreshold contrast adaptation to grating stimuli. These findings suggest that the visual system is equipped with mechanisms that conduct a global analysis of the plaid pattern, which are likely derived from the non-linear outputs of V1 complex cells.
关于整合方向和空间频率选择性通道输出的机制，我们了解得相当少。这些机制可以通过测量对复合刺激的选择性适应来研究，这种适应超出了仅对成分的适应所预期的程度（皮尔斯和泰勒，2006年）。在这里，我们研究了这些机制的对比度和空间相位依赖性。在一个视觉半视野中对一个格子进行适应，而同时在另一个半视野中对其组成光栅进行适应。格子选择性适应在高对比度探针下最为明显，而在低对比度下，对成分光栅刺激的适应占主导地位。这种格子选择性适应背后的机制似乎也对探针相对于适应器的空间相位不敏感，而我们发现超阈值对比度适应光栅刺激存在明显的相位依赖性。这些发现表明，视觉系统配备了对格子图案进行全局分析的机制，这些机制可能源自V1复合细胞的非线性输出。
