Measuring Sentence Information via Surprisal: Theoretical and Clinical Implications in Nonfluent Aphasia.
Measuring Sentence Information via Surprisal: Theoretical and Clinical Implications in Nonfluent Aphasia.
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通过惊喜测量句子信息：非流利失语症的理论和临床意义。
DOI：
10.1002/ana.26744
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发表时间：
2023
影响因子：
11.2
通讯作者：
Dickerson,BradfordC
中科院分区：
文献类型：
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作者：
Rezaii,Neguine;Michaelov,James;Josephy-Hernandez,Sylvia;Ren,Boyu;Hochberg,Daisy;Quimby,Megan;Dickerson,BradfordC
目的不流利失语症的特点是句子结构简化和词级异常，包括动词和功能词的使用减少。关于这种疾病机制的主要观点是，语法处理的核心缺陷会导致结构和单词级别的异常。在这里，我们提出基于信息论的另一种观点来解释非流利性失语症的症状。我们假设不流利的词级特征构成了一个独特的补偿过程，将句子的信息内容增强到健康说话者的水平。我们将这个过程称为词汇压缩。 方法我们使用基于语言模型的计算方法通过惊喜来测量句子信息，惊喜是根据单词在句子中出现的平均概率计算的，给定其先前的上下文。我们将此方法应用于不流利的原发性进行性失语症患者（nfvPPA；n = 36）和健康对照者（n = 133）描述图片时的语言。结果我们发现，nfvPPA患者通过在结构贫乏的句子中使用更丰富的单词，产生了与健康对照者相同的句子令人惊讶的句子。此外，nfvPPA 句子中较高的惊讶与语法错误的典型特征相关：较低的功能与所有单词的比率、较低的动词与名词的比率、较高的重动词与所有动词的比率以及较高的 ‐ing 形式动词的比率。需要修改非流利语言产生的治疗方法。安神经学 2023；94：647–657
ObjectiveNonfluent aphasia is characterized by simplified sentence structures and word‐level abnormalities, including reduced use of verbs and function words. The predominant belief about the disease mechanism is that a core deficit in syntax processing causes both structural and word‐level abnormalities. Here, we propose an alternative view based on information theory to explain the symptoms of nonfluent aphasia. We hypothesize that the word‐level features of nonfluency constitute a distinct compensatory process to augment the information content of sentences to the level of healthy speakers. We refer to this process as lexical condensation.MethodsWe use a computational approach based on language models to measure sentence information through surprisal, a metric calculated by the average probability of occurrence of words in a sentence, given their preceding context. We apply this method to the language of patients with nonfluent primary progressive aphasia (nfvPPA; n = 36) and healthy controls (n = 133) as they describe a picture.ResultsWe found that nfvPPA patients produced sentences with the same sentence surprisal as healthy controls by using richer words in their structurally impoverished sentences. Furthermore, higher surprisal in nfvPPA sentences correlated with the canonical features of agrammatism: a lower function‐to‐all‐word ratio, a lower verb‐to‐noun ratio, a higher heavy‐to‐all‐verb ratio, and a higher ratio of verbs in ‐ing forms.InterpretationUsing surprisal enables testing an alternative account of nonfluent aphasia that regards its word‐level features as adaptive, rather than defective, symptoms, a finding that would call for revisions in the therapeutic approach to nonfluent language production. ANN NEUROL 2023;94:647–657