Search Abstracts | Symposia | Slide Sessions | Poster Sessions
MEG recordings during delayed picture naming tasks revealed working memory activity specific to language production.
Poster Session F, Friday, October 2, 2:45 - 4:45 pm, Wangari Maathai
Mana Tanifuji1, Jihyun Park1, Atsushi Miura1, Shinji Nishimoto2,3,4, Hiromu Sakai1; 1Waseda University, 2Graduate School of Frontier Biosciences, The University of Osaka, 3Graduate School of Medicine, The University of Osaka, 4Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology
Human frontal lobes are functionally important in language processing. Specifically, the inferior frontal gyrus including Broca’s area is known as a region essential for language production. However, the specific role of Broca’s area is not well defined. Patient studies suggest that this area is involved in fluency, articulation, word-finding, repetition and the production and comprehension of complex grammatical structures (Dronkers, et al., 2007). Furthermore, frontal regions other than inferior frontal gyrus are also involved in language processing. The functional roles of the frontal lobe in language processing are still elusive. A characteristic feature of the frontal lobe is working memory. Working memory involves sustained activity that links different cognitive components. For example, a previous study demonstrates working memory activity when monkeys performed a categorization task: categorizing pictures of dog-like cats and cat-like dogs into dog and cat categories. In this task, a picture was presented for a short period of time, called sample period, and the monkeys assigned the picture to one of two categories after a certain delay period (Freedman, et al, 2002). They found neural activity in the dorsolateral prefrontal cortex during the delay period that linked the picture presented during the sample period to one of the categories. The present study aimed to explore the functional roles of the frontal lobe in language production by examining working memory activity during delay periods. To do so, we asked human subjects to conduct three versions of delayed picture naming tasks and investigated neural activity in delay periods. We recorded MEG signals during the tasks and the sources were estimated using minimum norm source localization to identify delay-period neural activity. In delayed picture naming tasks, articulation is temporally separated from activities related to language production. Consequently, the observed neural activity is less likely to be distorted by EMG and physical motion artifacts associated with articulation. A previous MEG study also revealed that reproducible activity can be obtained by using a delayed picture naming task (Ala-Salomäki, et al., 2025). We employed three versions of delayed picture naming tasks. In these tasks, the delay period followed the sample period and then a ‘go’ or ‘nogo’ cue was given. Subjects had to name the object only when the cue was ‘go’. In the first task, a picture of an object was presented during the sample period. In the second task, an object picture or scrambled image was presented during the sample period. In this case, subjects were required to articulate only when an objects was presented and the cue was ‘go’. In the third task, an object from one of two categories, animate and inanimate, was presented during the sample period. In this task subjects had to articulate when the sample object belonged to the predefined category and the cue was ‘go’. Based on these tasks, we found delayed-period activities specific to particular components of language production. This activity was not limited to the inferior frontal gyrus, but was also found in dorsolateral frontal lobe, and premotor cortex.
Topic Areas: Language Production, Methods