McGill University, Canada.
J Cogn Neurosci. 2010 Apr;22(4):670-82. doi: 10.1162/jocn.2009.21217.
The purpose of our study was to investigate the ability to process achromatic and short-wavelength-sensitive cone (S-cone)-isolating (blue-yellow) stimuli in the blind visual field of hemispherectomized subjects and to demonstrate that blindsight is mediated by a collicular pathway that is independent of S-cone inputs. Blindsight has been described as the ability to respond to visual stimuli in the blind visual field without conscious awareness [Weiskrantz, L., Warrington, E. K., Sanders, M. D., & Marshall, J. Visual capacity in the hemianopic field following a restricted occipital ablation. Brain, 97, 709-728, 1974]. The roles of the subcortical neural structures in blindsight, such as the pulvinar and the superior colliculus, have been debated and an underlying neural correlate has yet to be confirmed. Using fMRI, we tested the ability to process visual stimuli that isolated the achromatic and short-wavelength-sensitive (S-)-cone pathways in three subjects: one control subject, one hemispherectomized subject with blindsight, and one hemispherectomized subject without blindsight. We demonstrated that (1) achromatic and S-cone-isolating stimuli presented to the normal visual hemifield of hemispherectomized subjects and to both visual hemifields of the control subject activated contralateral visual areas (V1/V2), as expected; (2) achromatic stimulus presentation but not S-cone-isolating stimulus presentation to the blind hemifield of the subject with blindsight activated visual areas FEF/V5; (3) whereas the cortical activation of the control subject was enhanced by an additional stimulus (achromatic and S-cone isolating) presented in the contralateral visual field, activation pattern of the subject with blindsight was enhanced by achromatic stimuli only. We conclude that the human superior colliculus is blind to the S-cone-isolating stimuli, and blindsight is mediated by an S-cone-independent collicular pathway.
我们的研究目的是探究在大脑半球切除术患者的半视野中处理非彩色和短波长敏感视锥（S-锥）分离（蓝-黄）刺激的能力，并证明盲视是由一个独立于 S-锥输入的丘系通路介导的。盲视被描述为在没有意识觉察的情况下对盲视野中的视觉刺激做出反应的能力[Weiskrantz, L., Warrington, E. K., Sanders, M. D., & Marshall, J. 在限制的枕叶切除术后的半视野中视觉能力。大脑，97, 709-728, 1974]。盲视的皮质下神经结构的作用，如丘脑枕和上丘，一直存在争议，尚未证实其潜在的神经相关性。我们使用 fMRI 测试了 3 名受试者（1 名对照受试者、1 名有盲视的大脑半球切除术患者和 1 名没有盲视的大脑半球切除术患者）处理分离非彩色和短波长敏感（S-）视锥通路的视觉刺激的能力。我们证明：(1) 向大脑半球切除术患者的正常视野和对照受试者的两个视野呈现非彩色和 S-锥分离刺激，如预期的那样，激活了对侧视觉区域（V1/V2）；(2) 向有盲视的大脑半球切除术患者的盲视野呈现非彩色刺激，但不呈现 S-锥分离刺激，激活了 FEF/V5 等视觉区域；(3) 对照受试者的皮质激活因对侧视野中呈现的额外刺激（非彩色和 S-锥分离）而增强，而有盲视的受试者的激活模式仅因非彩色刺激而增强。我们的结论是，人类上丘对 S-锥分离刺激是盲视的，盲视是由一个独立于 S-锥的丘系通路介导的。
