Morland A B, Jones S R, Finlay A L, Deyzac E, Lê S, Kemp S
Physics Department, Blackett Laboratory, Imperial College, London, UK.
Brain. 1999 Jun;122 ( Pt 6):1183-98. doi: 10.1093/brain/122.6.1183.
Human patients rendered cortically blind by lesions to V1 can nevertheless discriminate between visual stimuli presented to their blind fields. Experimental evidence suggests that two response modes are involved. Patients are either unaware or aware of the visual stimuli, which they are able to discriminate. However, under both conditions patients insist that they do not see. We investigate the fundamental difference between percepts derived for the normal and affected hemifield in a human hemianope with visual stimuli of which he was aware. The psychophysical experiments we employed required the patient, GY, to make comparisons between stimuli presented in his affected and normal hemifields. The subject discriminated between, and was allowed to match, the stimuli. Our study reveals that the stimulus parameters of colour and motion can be discriminated and matched between the normal and blind hemifields, whereas brightness cannot. We provide evidence for associations between the percepts of colour and motion, but a dissociation between the percepts of brightness, derived from the normal and hemianopic fields. Our results are consistent with the proposal that the perception of different stimulus attributes is expressed in activity of functionally segregated visual areas of the brain. We also believe our results explain the patient's insistence that he does not see stimuli, but can discriminate between them with awareness.
因V1区受损而导致皮质盲的人类患者，仍能区分呈现于其盲视野的视觉刺激。实验证据表明涉及两种反应模式。患者要么未意识到视觉刺激，要么虽能区分却意识到了视觉刺激。然而，在这两种情况下，患者都坚称自己看不见。我们用患者能意识到的视觉刺激，研究了人类偏盲患者正常半视野和患侧半视野所产生的知觉之间的根本差异。我们采用的心理物理学实验要求患者GY对呈现于其患侧半视野和正常半视野的刺激进行比较。受试者要区分并能够匹配这些刺激。我们的研究表明，颜色和运动的刺激参数在正常半视野和盲半视野之间能够被区分和匹配，而亮度则不能。我们为颜色和运动知觉之间的关联提供了证据，但为正常视野和偏盲视野所产生的亮度知觉之间的分离提供了证据。我们结果与以下观点一致：不同刺激属性的知觉在大脑功能上分离的视觉区域的活动中得以体现。我们还认为，我们的结果解释了患者坚称自己看不见刺激，但却能在有意识的情况下对其进行区分的现象。
