Division of Psychiatry, School of Psychology, University of Nottingham, Nottingham, United Kingdom.
PLoS One. 2012;7(7):e42175. doi: 10.1371/journal.pone.0042175. Epub 2012 Jul 30.
Schizophrenia encompasses a wide variety of cognitive dysfunctions, a number of which can be understood as deficits of inhibition. To date, no research has examined 'conditioned inhibition' in schizophrenia--the ability of a stimulus that signals the absence of an expected outcome to counteract the conditioned response produced by a signal for that outcome (a conditioned excitor). A computer-based task was used to measure conditioned excitation and inhibition in the same discrimination procedure, in 25 patients with a confirmed diagnosis of schizophrenia and a community-based comparison sample. Conditioned inhibition was measured by a ratio score, which compared the degree to which the inhibitory stimulus and a neutral control stimulus reduced conditioned responding to the excitatory cue: the lower the ratio, the greater the inhibitory learning. At test the ratios were 0.45 and 0.39 for patient and control groups respectively, and the relevant interaction term of the ANOVA confirmed that the degree of inhibition was reduced in the patient group, with an effect size of r = 0.28.These results demonstrate for the first time that inhibitory learning is impaired in schizophrenia. Such an impairment provides an attractive framework for the interpretation of the positive symptoms of schizophrenia. However, we were unable to demonstrate any relationship between the level of conditioned inhibition and medication. Similarly, in the present study it must be emphasised that the available data did not demonstrate any relationship between individual variation in inhibitory learning and the level of positive symptoms as measured by the PANSS. In fact inhibitory learning impairment was relatively greater in participants with a predominantly negative symptom profile and their excitatory learning was also reduced. Accordingly the next step will be to investigate such relationships in a larger sample with a priori defined sub-groups displaying predominantly positive versus predominantly negative symptoms.
精神分裂症包括广泛的认知功能障碍，其中一些可以被理解为抑制的缺陷。迄今为止，还没有研究检查过精神分裂症中的“条件抑制”——一种信号表示预期结果不存在的刺激，以抵消该结果信号产生的条件反应（条件激发器）的能力。一项基于计算机的任务用于在相同的辨别程序中测量精神分裂症确诊患者和基于社区的对照组中的条件激发和条件抑制。条件抑制通过比率得分来衡量，该得分比较了抑制性刺激和中性对照刺激对兴奋性线索的条件反应的抑制程度：比率越低，抑制性学习程度越高。在测试中，患者组和对照组的比率分别为 0.45 和 0.39，方差分析的相关交互项证实了患者组的抑制程度降低，效应量 r = 0.28。这些结果首次证明了精神分裂症中的抑制性学习受损。这种损伤为解释精神分裂症的阳性症状提供了一个有吸引力的框架。然而，我们无法证明条件抑制水平与药物之间存在任何关系。同样，在本研究中必须强调的是，可用数据并未证明抑制性学习的个体差异与 PANSS 测量的阳性症状水平之间存在任何关系。事实上，在以阴性症状为主的参与者中，抑制性学习的损伤相对更大，他们的兴奋性学习也减少了。因此，下一步将在具有预先定义的以阳性症状为主与以阴性症状为主的亚组的更大样本中研究这些关系。
