Seven-dimensional Connectivity Atlas of Human Language
Abstract number :
2.316
Submission category :
5. Neuro Imaging / 5B. Functional Imaging
Year :
2024
Submission ID :
745
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Yu Kitazawa, MD, PhD – Yokohama City University
Kazuki Sakakura, MD, PhD – Rush University
Hiroshi Uda, MD/PhD – Wayne State University
Naoto Kuroda, MD – Wayne State University
Riyo ueda, MD, PhD – Wayne State University
Ethan Firestone, MD-PhD Candidate – Wayne State University
Min-Hee Lee, PhD – Wayne State University
Jeong-Won Jeong, PhD – Wayne State University
Masaki Sonoda, MD, PhD – Yokohama City University
Shin-ichiro Osawa, MD, PhD – Tohoku University Graduate School of Medicine
Kazushi Ukishiro, MD, PhD – Tohoku University Graduate School of Medicine
Makoto Ishida, PhD – Tohoku University
Kazuo Kakinuma, MD, PhD – Tohoku University
Shoko Ota, PhD – Tohoku University
Yutaro Takayama, MD, PhD – Department of Neurosurgery, Yokohama City University
Keiya Iijima, MD, PhD – National Center of Neurology and Psychiatry
Toshimune Kambara, PhD – Hiroshima University
Hidenori Endo, MD, PhD – Tohoku University
Kyoko Suzuki, MD, PhD – Tohoku University
Nobukazu Nakasato, MD, PhD – Tohoku University Graduate School of Medicine
Masaki Iwasaki, MD, PhD – National Center of Neurology and Psychiatry
Fumiaki Tanaka, MD, PhD – Yokohama City University
Eishi Asano, MD/PhD – Wayne State University
Rationale: Current neurobiological models detail cortical dynamics in language processing but fall short in capturing the spatiotemporal dynamics of directional neural interactions within white matter networks. This study aimed to visualize intracranial cortical high-gamma activity dynamics, alongside functional and effective connectivity via specific white matter pathways, when individuals comprehended and responded to the questions.
Methods: We studied 40 Japanese-speaking patients with focal epilepsy who underwent intracranial EEG before resective surgery. Each patient underwent naming tasks based on auditory descriptive questions. We declared that functional connectivity was significantly enhanced (or diminished) if two cortical regions showed simultaneous, significant, and sustained high-gamma augmentation (or attenuation) and also if these cortical regions were directly connected by a white matter tract on tractography. We declared that a facilitatory (or suppressive) information flow occurred from one cortical region to another if, across such a white matter tract, an increase (or decrease) in high-gamma amplitude was predictive of a subsequent increase (or decrease) in a distinct cortical region.
Results: Upon hearing a wh-interrogative at question onset, we observed an enhancement of inter-hemispheric functional connectivity with a left-to-right callosal facilitatory information flow between superior-temporal gyri (Fig. 1a), contrasted by functional connectivity diminution with a right-to-left callosal suppressive flow between dorsolateral prefrontal regions (Fig. 1b). Upon processing verbs with concrete objects or adverbs, we detected a shift favoring intra-hemispheric over inter-hemispheric functional connectivity, marked by bidirectional information flows through extensive white matter pathways, including the arcuate fasciculus, within the left hemisphere (Fig. 2b, 2d, and 2e). Around question offset, trials asking ‘what’ induced greater neural engagement in the left posterior inferior-frontal gyrus compared to those asking ‘where’. This ‘what’-preferential neural engagement is associated with functional connectivity enhancement with bidirectional information flows, to the left middle/inferior-temporal gyri via the arcuate fasciculus. During overt responses, we observed an enhancement of inter-hemispheric functional connectivity, characterized by bidirectional callosal information flows between Rolandic areas (Fig. 2c and 2f), and individuals with higher IQ exhibit less lingering neural engagement in the left posterior middle-frontal gyrus.
Conclusions: Our findings propose a novel neurobiological framework for understanding human language processing. This framework emphasizes the spatiotemporal dynamics of directional neural interactions within white matter networks. The resulting atlas has the potential to serve as a valuable asset for planning resective surgery in patients with focal epilepsy.
Funding: JSPS JP22J23281 (to N.K.), JSPS JP22KJ0323 (to N.K.), Grant in Aid for Scientific Research (B) 21H03779 (to K.S.)
Neuro Imaging