Cass John R, Spehar Branka
Department of Physiology, University of Sydney, Anderson Stuart Building (F13), Sydney, NSW 2006, Australia.
Vision Res. 2005 Nov;45(24):3060-73. doi: 10.1016/j.visres.2005.08.003.
Psychophysical studies have found that contrast sensitivity is enhanced by spatially separated flanking stimuli that are collinear with a foveal target. Considerable uncertainty remains, however, about the facilitative effect of other surround configurations. We investigated this by systematically manipulating relative flanker position (target end-zones or side-bands) and orientation (iso-oriented or ortho-oriented targets and flankers) at multiple target-flanker separations. We also examined the effect of a temporal dimension (exposure duration) across combinations of these spatial parameters. We found facilitation in the context of all surround configurations tested, but not at all separations and exposure durations. Interestingly, although the minimum exposure required to induce facilitation (facilitative delay) increased as a function of separation for all configurations (averaged across subjects), the rate at which this occurred depended, not upon flanker position or orientation relative to the target, but the alignment of the flankers relative to each other. By transforming these slopes into striate transmission speeds we estimate that: (i) collinear flanker facilitation matches the slow conduction velocities of long-range (LR) horizontal striate connections and (ii) non-collinear, parallel flanker facilitation correlates with the much faster extra-striate feedforward/feedback connections.
心理物理学研究发现，与中央凹目标共线的空间分离侧翼刺激会增强对比度敏感性。然而，关于其他周边配置的促进作用仍存在相当大的不确定性。我们通过在多个目标 - 侧翼间距下系统地操纵相对侧翼位置（目标端区或边带）和方向（同向或正交目标与侧翼）来对此进行研究。我们还研究了这些空间参数组合下时间维度（曝光持续时间）的影响。我们发现在所有测试的周边配置情况下都存在促进作用，但并非在所有间距和曝光持续时间下都如此。有趣 的是，尽管诱导促进作用所需的最短曝光时间（促进延迟）在所有配置下（受试者平均）都随间距增加而增加，但这种增加的速率并不取决于侧翼相对于目标的位置或方向，而是取决于侧翼彼此之间的对齐方式。通过将这些斜率转换为纹状 体传输速度，我们估计：（i）共线侧翼促进作用与长程（LR）水平纹状连接的慢传导速度相匹配，（ii）非共线、平行侧翼促进作用与快得多的纹外前馈/反馈连接相关。
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