Open AccessConnectivity Gradient in the Human Left Inferior Frontal Gyrus: Intraoperative Cortico-Cortical Evoked Potential Study
Author(s) -
Takuro Nakae,
Riki Matsumoto,
Takeharu Kunieda,
Yoshiki Arakawa,
Katsuya Kobayashi,
Akihiro Shimotake,
Yukihiro Yamao,
Takayuki Kikuchi,
Toshihiko Aso,
Masao Matsuhashi,
Kazumichi Yoshida,
Akio Ikeda,
Ryōsuke Takahashi,
Matthew A. Lambon Ralph,
Susumu Miyamoto
Publication year - 2020
Publication title -
cerebral cortex
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.694
H-Index - 250
eISSN - 1460-2199
pISSN - 1047-3211
DOI - 10.1093/cercor/bhaa065
Subject(s) - supramarginal gyrus , arcuate fasciculus , angular gyrus , temporal lobe , inferior frontal gyrus , superior temporal gyrus , neuroscience , anatomy , frontal lobe , parietal lobe , psychology , biology , medicine , magnetic resonance imaging , epilepsy , diffusion mri , functional magnetic resonance imaging , tractography , radiology
In the dual-stream model of language processing, the exact connectivity of the ventral stream to the anterior temporal lobe remains elusive. To investigate the connectivity between the inferior frontal gyrus (IFG) and the lateral part of the temporal and parietal lobes, we integrated spatiotemporal profiles of cortico-cortical evoked potentials (CCEPs) recorded intraoperatively in 14 patients who had undergone surgical resection for a brain tumor or epileptic focus. Four-dimensional visualization of the combined CCEP data showed that the pars opercularis (Broca’s area) is connected to the posterior temporal cortices and the supramarginal gyrus, whereas the pars orbitalis is connected to the anterior lateral temporal cortices and angular gyrus. Quantitative topographical analysis of CCEP connectivity confirmed an anterior–posterior gradient of connectivity from IFG stimulus sites to the temporal response sites. Reciprocality analysis indicated that the anterior part of the IFG is bidirectionally connected to the temporal or parietal area. This study shows that each IFG subdivision has different connectivity to the temporal lobe with an anterior–posterior gradient and supports the classical connectivity concept of Dejerine; that is, the frontal lobe is connected to the temporal lobe through the arcuate fasciculus and also a double fan-shaped structure anchored at the limen insulae.