Chen Yue, Levy Deborah L, Sheremata Summer, Holzman Philip S
Department of Psychiatry, Harvard Medical School and McLean Hospital, Mailman Research Center, 115 Mill Street, Belmont, MA 02478, USA.
Biol Psychiatry. 2004 Apr 15;55(8):834-41. doi: 10.1016/j.biopsych.2003.12.024.
Visual motion processing is compromised in schizophrenia, as shown in deficient velocity discrimination. Processing of motion signals comprises progressive stages along the geniculate-striate-extrastriate-cortex pathway. Based on neurophysiologic and brain lesion studies, a velocity discrimination deficit can implicate early-stage motion processing if it is contrast-dependent or late-stage motion processing if it is contrast-independent.
To determine which stage underlies the deficient velocity discrimination in schizophrenia, we examined the effects of visual contrast on velocity discrimination. We measured velocity discrimination thresholds in schizophrenia patients (n = 34) and normal control subjects (n = 17) at both low and high contrasts, using each subject's contrast detection threshold to equate contrast levels.
Schizophrenia patients showed poor velocity discrimination that improved little with high contrast, whereas normal control subjects showed enhanced velocity discrimination with increased contrast.
The finding that the velocity discrimination deficit in schizophrenia is independent of contrast modulation implicates the later, rather than the earlier, stages of motion processing, which is mediated in the extrastriate cortex.
精神分裂症患者的视觉运动处理能力受损，这在速度辨别缺陷中有所体现。运动信号的处理沿着膝状体 - 纹状体 - 纹外皮层 - 皮层通路包含多个递进阶段。基于神经生理学和脑损伤研究，如果速度辨别缺陷依赖于对比度，则表明早期运动处理存在问题；如果不依赖于对比度，则表明晚期运动处理存在问题。
为了确定精神分裂症患者速度辨别缺陷背后的是哪个阶段，我们研究了视觉对比度对速度辨别的影响。我们在低对比度和高对比度条件下，测量了精神分裂症患者（n = 34）和正常对照受试者（n = 17）的速度辨别阈值，使用每个受试者的对比度检测阈值来使对比度水平相等。
精神分裂症患者表现出较差的速度辨别能力，高对比度时改善甚微，而正常对照受试者随着对比度增加速度辨别能力增强。
精神分裂症患者的速度辨别缺陷与对比度调制无关这一发现表明，运动处理的后期阶段而非早期阶段存在问题，后期阶段由纹外皮层介导。
