Authors :
Presenting Author: Aya Kanno, MD, PhD – Sapporo Medical University
Ryuzaburo Kochi, MD, PhD – Wayne State University
Kazuki Sakakura, MD, PhD – Rush University
Yu Kitazawa, MD, PhD – Yokomaha City University Graduate School of Medicine
Hiroshi Uda, MD, PhD – Wayne State University
Riyo Ueda, MD, PhD – Wayne State University
Masaki Sonoda, MD, PhD – Yokohama City University Graduate School of Medicine
Min-Hee Lee, PhD – Wayne State University
Jeong-Won Jeong, PhD – Wayne State University
Robert Rothermel, PhD – Wayne State University
Aimee Luat, MD – Children’s Hospital of Michigan
Eishi Asano, MD, PhD – Wayne State University
Rationale:
Humans understand and respond to spoken questions through coordinated activity across distributed cortical networks. The present study clarified the causal roles of alternating network engagement across multiple white matter bundles—an area understudied at the whole-brain scale.
Methods:
Using intracranial high-gamma activity recorded from 7,792 non-epileptic electrode sites in 106 epilepsy patients who underwent direct cortical stimulation mapping, we constructed an atlas visualizing the millisecond-scale dynamics of functional coactivation and co-inactivation networks during a naming task conducted in response to auditory questions.
Results:
This atlas, termed the Dynamic Causal Tractography Atlas, identified functional coactivation patterns within specific time windows that were most strongly associated with stimulation-induced language and speech manifestations (p-value range: 2.5 × 10-5 to 6.6 × 10-14; rho range: +0.54 to +0.82). The atlas revealed that no single intra-hemispheric fasciculus was consistently engaged in all naming stages; instead, each fasciculus supported specific stages, with multiple distinct major fasciculi simultaneously contributing to each stage. Additionally, this atlas identified the specific linguistic stages and fasciculi where handedness effects became evident.
Conclusions:
Our findings clarify the dynamics and causal roles of alternating, coordinated neural activity through specific fasciculi during auditory descriptive naming, advancing current neurobiological models of speech network organization. Our atlas may aid language mapping in patients undergoing epilepsy surgery.
Funding:
Japan-U.S. Brain Research Cooperation Program, JERF TENKAN 22102, The ITO Foundation, Cheiron-GIFTS 2023 (to A.K.)
NIH: R01 NS089659 (to J.W.J.).
NIH: R01 NS064033 (to E.A.).