Kielar Aneta, Milman Lisa, Bonakdarpour Borna, Thompson Cynthia K
Aphasia and Neurolinguistics Research Laboratory, Northwestern University, USA.
J Neurolinguistics. 2011 Mar;24(2):183-201. doi: 10.1016/j.jneuroling.2010.02.008.
Most neuroimaging studies examining verb morphology have focused on verb tense, with fewer examining agreement morphology, and no previous fMRI studies have investigated distinctions between past and present tense inflection. However, models of language representation and processing suggest differences in where these inflections are instantiated in the phrase structure as well as differences in the linguistic functions they serve, suggesting unique neural networks for these forms. In addition, results of available neuroimaging studies of grammatical morphology vary considerably due to methodological differences. Some studies have used overt production tasks, whereas others have used covert tasks. In the present study we examined brain activation associated with past tense and present tense/agreement morphology under overt and covert production conditions in 13 healthy adults using an event-related functional magnetic resonance imaging (fMRI) design. Production of verbs inflected for past tense (V + -ed) and present tense/agreement (V -s) was elicited using temporal adverbs (i.e. Yesterday, Nowadays). Results showed that in healthy adults inflecting both past tense and agreement morphology (compared to a verb stem production condition) recruited not only left inferior frontal structures, but also motor and premotor cortices, and posterior parietal regions. Activation also was observed in the basal ganglia, thalamus, and the cingulate gyrus. Past tense and present tense/agreement recruited partially overlapping tissue in these regions, with distinctions observed for the two forms in frontal and parietal brain areas. We also found that activation varied with task demands, with more extensive frontal activation noted in the overt compared to the covert verb inflection task. These results are consistent with the hypothesis that the neural signatures for verb inflection differ from that for verb stems alone and involve a distributed frontal and parietal network of brain regions. Further, the neural tissue recruited for instantiation of past tense versus present tense/agreement morphology is distinct, supporting linguistic theories that differentiate the two forms.
大多数研究动词形态的神经影像学研究都聚焦于动词时态，较少研究一致形态，且此前没有功能磁共振成像（fMRI）研究探究过去时和现在时屈折变化之间的差异。然而，语言表征和处理模型表明，这些屈折变化在短语结构中的实例化位置存在差异，以及它们所发挥的语言功能也存在差异，这表明这些形式具有独特的神经网络。此外，由于方法上的差异，现有的语法形态神经影像学研究结果差异很大。一些研究使用了显性产出任务，而其他研究则使用了隐性任务。在本研究中，我们使用事件相关功能磁共振成像（fMRI）设计，在13名健康成年人的显性和隐性产出条件下，研究了与过去时和现在时/一致形态相关的大脑激活情况。使用时间副词（即昨天、如今）来引发过去时（V + -ed）和现在时/一致（V -s）屈折变化的动词产出。结果表明，在健康成年人中，与动词词干产出条件相比，对过去时和一致形态进行屈折变化不仅会激活左额下回结构，还会激活运动和运动前皮质以及顶叶后部区域。在基底神经节、丘脑和扣带回中也观察到了激活。过去时和现在时/一致形态在这些区域募集了部分重叠的组织，在额叶和顶叶脑区观察到了这两种形式的差异。我们还发现，激活随任务需求而变化，与隐性动词屈折任务相比，显性任务中额叶的激活范围更广。这些结果与以下假设一致，即动词屈折的神经特征不同于单独的动词词干，并且涉及大脑区域的分布式额叶和顶叶网络。此外，为过去时与现在时/一致形态实例化而募集的神经组织是不同的，这支持了区分这两种形式的语言学理论。
