A small number of studies have described verbal selection deficits in Parkinson’s disease (PD) when selection must occur among competing alternatives. However, these studies have largely focused on single-word processing, or have utilised sentence stems that carry high contextual constraint, thus reducing selection demands. The present study aimed to determine the influence of variable contextual constraint on the selection of a verbal response in PD. This was achieved using an adaption of the Hayling Sentence Completion Task whereby PD participants and matched controls were required to provide a single word to complete a cloze probability sentence stem that carried a low, medium, or high degree of contextual constraint. Results revealed no main effect of group in terms of response time or accuracy, though a group-by-condition interaction in accuracy was noted. This was characterised by a significant difference in accuracy between low and medium levels of constraint for control participants, but no significant difference for the PD group. Functional MRI data revealed marked between-group differences in underlying neural activity. The control group showed increased recruitment of the dorsal striatum and the vlPFC under conditions that placed greater demands upon selection (i.e. low and medium constraint), and greater activity overall in the left dlPFC and right vlPFC. However, in the PD group, behavioural performance appeared to be maintained despite underlying decreases in frontostriatal activity, suggesting other compensatory mechanisms that may include changes in functional connectivity or an over-medication effect in frontal networks in response to loss of signalling in cortico-subcortical pathways.

少数研究描述了当必须在竞争性替代方案中进行选择时，帕金森氏病（PD）中的言语选择缺陷。但是，这些研究主要集中在单词处理上，或者利用了带有较高上下文约束的句子词干，从而减少了选择需求。本研究旨在确定变量上下文约束对PD语言选择的影响。这是通过改编Hayling句子完成任务来实现的，根据该任务，PD参与者和匹配的控件需要提供一个单词来完成带有低，中或高度上下文约束的cloze概率句子的词干。结果显示，就响应时间或准确性而言，小组没有主要影响，尽管注意到了按条件分组的准确性。其特点是控制参与者的中低约束水平的准确性存在显着差异，而PD组则没有显着差异。功能性MRI数据显示基础神经活动之间存在明显的组间差异。对照组显示在对选择有更高要求（即低和中度约束）的条件下，背侧纹状体和vlPFC的募集增加，并且左dlPFC和右vlPFC的总体活动更大。然而，在PD组，尽管前额骨活动有所减少，但行为表现似乎得以保持，