The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA.
Schizophr Res. 2012 Aug;139(1-3):246-52. doi: 10.1016/j.schres.2012.05.022. Epub 2012 Jun 15.
Visual processing studies have repeatedly shown impairment in patients with schizophrenia compared to healthy controls. Electroencephalography (EEG) and, specifically, visual evoked potential (VEP) studies have identified an early marker of this impairment in the form of a decrement in the P1 component of the VEP in patients and their clinically unaffected first-degree relatives. Much behavioral and neuroimaging research has implicated specific dysfunction of either the subcortical magnocellular pathway or the cortical visual dorsal stream in this impairment. In this study, EEG responses were obtained to the contrast modulation of checkerboard stimuli using the VESPA (Visual Evoked Spread Spectrum Analysis) method. This was done for a high contrast condition and, in order to bias the stimuli towards the magnocellular pathway, a low contrast condition. Standard VEPs were also obtained using high contrast pattern reversing checkerboards. Responses were measured using high-density electrical scalp recordings in 29 individuals meeting DSM-IV criteria for schizophrenia and in 18 control subjects. Replicating previous research, a large (Cohen's d=1.11) reduction in the P1 component of the VEP was seen in patients when compared with controls with no corresponding difference in the VESPA response to high contrast stimuli. In addition, the low-contrast VESPA displayed no difference between patients and controls. Furthermore, no differences were seen between patients and controls for the C1 components of either the VEP or the high-contrast VESPA. Based on the differing acquisition methods between VEP and VESPA, we discuss these results in terms of contrast gain control and the possibility of dysfunction at the cortical level with initial afferent activity into V1 along the magnocellular pathway being intact when processing is biased towards that pathway using low contrast stimuli.
视觉处理研究反复表明，与健康对照组相比，精神分裂症患者存在损伤。脑电图（EEG），特别是视觉诱发电位（VEP）研究，已经确定了这种损伤的早期标志物，即 VEP 的 P1 成分在患者及其无临床症状的一级亲属中出现减少。大量行为和神经影像学研究表明，这种损伤与皮质视觉背流中的下丘脑海马细胞通路或皮质视觉背流中的特定功能障碍有关。在这项研究中，使用 VESPA（视觉诱发电位扩展谱分析）方法，对棋盘刺激的对比度调制进行了 EEG 反应。这是在高对比度条件下进行的，为了使刺激偏向于大细胞通路，采用了低对比度条件。还使用高对比度模式反转棋盘获得了标准 VEP。在 29 名符合 DSM-IV 精神分裂症标准的个体和 18 名对照受试者中，使用高密度头皮电记录测量了反应。复制先前的研究，与对照组相比，患者的 VEP 的 P1 成分明显减少（Cohen's d=1.11），而高对比度刺激的 VESPA 反应没有相应差异。此外，低对比度 VESPA 在患者和对照组之间没有差异。此外，无论是 VEP 还是高对比度 VESPA 的 C1 成分，患者和对照组之间均无差异。基于 VEP 和 VESPA 之间不同的采集方法，我们根据对比度增益控制以及皮质水平功能障碍的可能性，根据这些结果进行了讨论，当使用低对比度刺激使处理偏向于该通路时，大细胞通路中的初始传入活动进入 V1 保持完整。
