Comprehension of passive sentences in Japanese: An fMRI study

Satoru Yokoyama, Jobu Watanabe, Kazuki Iwata, Yuko Sassa, Naoki Miura, Hyeonjeong Jeong, Naho Ikuta, Yuko Akitsuki, Hideyuki Okamoto, Tomoki Haji, Nobuo Usui, Masato Taira, Wataru Nakamura, Shigeru Sato, Kaoru Horie, Ryuta Kawashima.

Abstract:

In a previous psychological study, it has been reported that comprehension of reversible passive sentences is more difficult than that of corresponding active sentences, although there is no significant difference between the comprehension of non-reversible passive sentences and that of the corresponding active sentences (Slobin, 1966). In aphasic studies, it has also been reported that aphasic patients find difficulty in comprehending reversible passive sentences and assigning thematic roles onto noun phrases, though they can comprehend active and non-reversible passive sentences (e.g., Caramazza and Miceli, 1991). In these psychological and aphasic studies, we can assume that comprehension of passive sentences is more difficult than that of corresponding active sentences in terms of the comprehension of which thematic role is assigned onto noun phrases.

In this study, we carried out an event-related functional magnetic resonance imaging study to investigate (i) how passive sentences are comprehended in the human brain compared with active sentences, and (ii) to determine which regions are involved in the comprehension of thematic roles. For this purpose, we asked twenty native speakers of Japanese to read an active or passive sentence in Japanese and to identify who the agent or patient was in that sentence.

The results showed that the reading of passive sentences showed significantly more activation of the left inferior parietal lobule when compared with the reading of the corresponding active sentences.

In previous imaging studies, it has also been reported that the left parietal region is activated during sentence comprehension tasks (e.g., Newman et al., 2003). Newman et al. (2003) has claimed that the use of spatial processes can occur during syntactic analysis and sentence comprehension, since it has been reported that parietal region is involved in mental rotation and mental image (e.g., Mellet et al., 1996). For example, during the comprehension of the sentence ‘Mary kicked John', the parietal region may be involved in generating a mental image of a girl kicking a boy (Newman et al., 2003). From these studies, we can assume that spatial information is employed to understand ‘who does what to whom' during sentence comprehension. Since the tasks used in the present study require the information regarding ‘who does what to whom', activation of the left inferior parietal lobule was prominent during reading passive sentences in this study.

Many lesion studies have reported and agreed that Broca's aphasic patients are unable to understand passive sentences whereas they can understand active sentences (e.g., Hagiwara, 1993; Grodzinsky, 1995). However, in recent lesion studies, lesions to Broca's area have not always caused Broca's aphasia. For example, Dronkers et al. (1996) has found that about half of patients with lesions to Broca's area have persistent Broca's aphasia. Furthermore, Caplan et al. (1996) has reported on a patient with a lesion confined to Broca's area but with 100% perfect performance on understanding passive sentences. As shown above, it is not assumed that brain damage to Broca's area selectively disrupts the comprehension of a passive sentence in lesion studies. It is postulated that the inferior parietal region is part of the perisylvian association cortex that is associated with language processing (Caplan et al., 2004). Therefore, we cannot reject the possibility of involvement of the left parietal region in the comprehension of passive sentences.