Heim Stefan, McMillan Corey T, Olm Christopher, Grossman Murray
Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, Jülich, Germany.
Department of Psychiatry, Psychotherapy, and Psychosomatics, Medical Faculty, RWTH Aachen University, Aachen, Germany.
Front Psychol. 2020 Apr 3;11:582. doi: 10.3389/fpsyg.2020.00582. eCollection 2020.
The processing of quantifier words such as "many" or "few" is a complex operation supported by a plastic fronto-parietal network predominantly in the left hemisphere. The internal reference criterion defining a quantifier (e.g., ≥50% for "many") can be modified in a learning paradigm. Most interestingly, changing the criterion for one quantifier also leads to a change in the criterion for the untrained quantifier, i.e., a semantic restructuring effect, which is supported by Broca's region in the left inferior frontal cortex. Here, we applied this paradigm to patients with the behavioral variant of fronto-temporal dementia (bvFTD) because they suffer from loss of cognitive flexibility, reduced ability to process quantities and their values, impaired reinforcement learning, and language comprehension deficits. The question was whether the patients would be able to perform the task, show direct learning of the new quantifier meanings, and exhibit cognitive flexibility in terms of semantic restructuring. Eleven bvFTD patients took part in two behavioral experiments. In Experiment 1, in a first baseline block, each individual's criterion for "many" and "few" was assessed. In block 2, subjects received feedback about their decisions. Contrary to their initial notion, a proportion of 40% yellow circles was reinforced as "many." In block 3, the effect of this training on their judgments of "many" and "few" was re-assessed. The group of bvFTD patients showed a learning effect for the new criterion trained for the quantifier "many," but failed to generalize this criterion shift to the other quantifier "few." Experiment 2 was similar to Experiment 1, but the patients were trained in Block 2 to judge 60% of circles as "few," with no training for "many." Again, there was an average learning effect for the trained quantifier "few" over the entire group, but no generalization to "many." Since the patients were still able to perform the task and showed learning of "many" to direct feedback, the data suggest that the generalization process, rather than initial learning, is more vulnerable to fronto-temporal degeneration.
对“许多”或“少数”等量词的处理是一项复杂的操作，主要由左半球一个具有可塑性的额顶叶网络支持。定义量词的内部参考标准（例如，“许多”为≥50%）可以在学习范式中进行修改。最有趣的是，改变一个量词的标准也会导致未训练量词的标准发生变化，即语义重构效应，这由左下额叶皮质的布罗卡区支持。在此，我们将此范式应用于行为变异型额颞叶痴呆（bvFTD）患者，因为他们存在认知灵活性丧失、处理数量及其值的能力下降、强化学习受损以及语言理解缺陷。问题在于患者是否能够完成任务、直接学习新的量词含义，并在语义重构方面表现出认知灵活性。11名bvFTD患者参与了两项行为实验。在实验1中，在第一个基线阶段，评估了每个个体对“许多”和“少数”的标准。在第2阶段，受试者收到关于其决策的反馈。与他们最初的观念相反，40%的黄色圆圈被强化为“许多”。在第3阶段，重新评估了这种训练对他们对“许多”和“少数”判断的影响。bvFTD患者组对为量词“许多”训练的新标准显示出学习效应，但未能将这种标准转变推广到另一个量词“少数”。实验2与实验1类似，但在第2阶段训练患者将60%的圆圈判断为“少数”，而未对“许多”进行训练。同样，整个组对训练的量词“少数”有平均学习效应，但未推广到“许多”。由于患者仍然能够完成任务并对“许多”的直接反馈表现出学习，数据表明泛化过程而非初始学习更容易受到额颞叶退化的影响。
