Delord Sandrine, Ducato Maria Giovanna, Pins Delphine, Devinck Frédéric, Thomas Pierre, Boucart Muriel, Knoblauch Kenneth
Equipe de Psychologie Cognitive, Laboratoire de Psychologie (EA 3662), Université Bordeaux 2, Bordeaux, France.
Vis Neurosci. 2006 May-Aug;23(3-4):645-50. doi: 10.1017/S0952523806233017.
Recently developed psychophysical techniques permit the biasing of the processing of the stimulus by early visual channels so that responses reflect characteristics of either magno- or parvocellular pathways (Pokorny & Smith, 1997). We used such techniques to test psychophysically whether the global magnocellular dysfunction reported in schizophrenia also affects early processes. Seven schizophrenic patients and 19 normal controls participated. The task was a four-alternative forced-choice luminance discrimination, using a 2 x 2 configuration of four 1-deg squares. Target luminance threshold was determined in three conditions: the stimulus, including the target, was pulsed for 17 ms (pulse paradigm); the target was presented on a steady background of four squares (steady paradigm), or the target was presented alone (no background paradigm). We replicated previous results demonstrating magnocellular and parvocellular signatures in control participants. No evidence for an early magnocellular deficit could be detected as the thresholds of all schizophrenic observers were higher both in the steady paradigm (presumed magnocellular mediation) and in the pulse paradigm (presumed parvocellular mediation). Magnocellular dysfunction, if present in schizophrenia, must concern more integrated processes, possibly at levels at which parvocellular and magnocellular paths interact.
最近开发的心理物理学技术能够通过早期视觉通道对刺激处理过程施加偏差，从而使反应反映大细胞或小细胞通路的特征（波科尔尼和史密斯，1997年）。我们使用这些技术进行心理物理学测试，以探究精神分裂症中报告的整体大细胞功能障碍是否也会影响早期过程。七名精神分裂症患者和19名正常对照者参与了研究。任务是进行四选一的强制选择亮度辨别，采用四个1度正方形的2×2排列。在三种条件下确定目标亮度阈值：包括目标在内的刺激以17毫秒脉冲呈现（脉冲范式）；目标呈现在四个正方形的稳定背景上（稳定范式），或者单独呈现目标（无背景范式）。我们重复了之前在对照参与者中证明大细胞和小细胞特征的结果。由于所有精神分裂症观察者在稳定范式（假定为大细胞介导）和脉冲范式（假定为小细胞介导）下的阈值都较高，因此未检测到早期大细胞缺陷的证据。如果精神分裂症中存在大细胞功能障碍，那么它必定与更综合的过程有关，可能是在小细胞和大细胞通路相互作用的水平上。
