Triangulating the Neural Cornerstones of Reading: Within-participant Contrastive Dissociations Induced by Direct Cortical Stimulation
Abstract number :
3.351
Submission category :
11. Behavior/Neuropsychology/Language / 11A. Adult
Year :
2022
Submission ID :
2204601
Source :
www.aesnet.org
Presentation date :
12/5/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:25 AM
Authors :
Masako Daifu-Kobayashi, MD – Kyoto University Graduate School of Medicine, Japan; Riki Matsumoto, MD., PhD. – Professor, Neurology, Kobe University Graduate School of Medicine, Japan; Akihiro Shimotake, MD., PhD. – Neurology – Kyoto University Graduate School of Medicine, Japan; Ota Makiko, MD. – Neurology – Kyoto University Graduate School of Medicine, Japan; Mitsuhiro Sakamoto, MD. – Neurology – Kyoto University Graduate School of Medicine, Japan; Katsuya Kobayashi, MD., PhD. – Neurology – Kyoto University Graduate School of Medicine, Japan; Takayuki Kikuchi, MD., PhD. – Neurosurgery – Kyoto University Graduate School of Medicine, Japan; Kazumichi Yoshida, MD., PhD. – Neurosurgery – Kyoto University Graduate School of Medicine, Japan; takeharu Kunieda, MD., PhD. – Professor, Neurosurgery, Ehime University Graduate School of Medicine, Japan; Ryosuke Takahashi, MD., PhD. – Professor, Neurology, Kyoto University Graduate School of Medicine, Japan; Matthe A. Lambon Ralph, PhD. – Professor, MRC Cognition and Brain Sciences Unit, University of Cambridge, UK; Akio Ikeda, MD., PhD. – Professor, Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan
Rationale: What are the neural bases and processes that allow the human brain to recognize a written word and read it aloud? This study was motivated by the neurocognitive framework which proposes three cognitive systems: visual-orthographics, phonology and semantics. Many studies with multiple modalities have revealed that the anterior temporal lobe (ATL) contributes to semantic system, whereas the ventral occipitotemporal region relates to visual processing. Phonological processing is supported by a network consisting of inferior prefrontal cortex, posterior superior temporal gyrus as well as the supramarginal gyrus (SMG). This study explored the contrastive effects of transient cortical stimulation to each of these three regions within the same patient.
Methods: Five patients with intractable temporal lobe epilepsy who underwent presurgical evaluation with subdural electrode implantation over language-dominant ventral ATL were included (IRB C533). We used 120 kanji words consisting of two characters from Fushimi et al. 1999, and classified them into three types: consistent (C: associated with only one pronunciation), inconsistent typical (IT: two or more possible ways of pronunciation but the correct pronunciation is the most common), and inconsistent atypical (IA: the same as IT except the correct pronunciation is in the minority). 56 kana non-words with 2 to 5 mora were also employed from the SALA battery (Japanese version of PALPA). Low-intensity direct cortical stimulation (DCS) was applied to the anterior (< 6 cm from the temporal pole), the posterior ( >6 cm) basal temporal language area (aBTLA, pBTLA) and the SMG (only in Patient 5). Low-intensity DCS (50 Hz, 3 mA (BTLA) and 9 mA (SMG), 3 sec, half trials) or sham stimulation (0 mA, half trials) was delivered time-locked to the presentation of the kanji word and kana non-word. We evaluated reaction time (RT) using ANOVA.
Results: In Patient 5 in whom DCS was applied to the aBTLA and SMG, DCS to the aBTLA prolonged RT in kanji reading, but not in kana non-word. Significant interactions were observed between kanji type and stimulation (between C and IA). In the SMG stimulation, RT was prolonged both for kanji word and kana non-word reading. Significant interactions were observed between kana mora and stimulation. In the comparison between the aBTLA and pBTLA, DCS to the aBTLA significantly prolonged RT in kanji word reading, but not in kana non-word. Significant interactions were observed between kanji type and stimulation (between C and IA). In the pBTLA stimulation, RT was prolonged both for kanji word and kana non-word reading. Significant interactions were observed between kana mora and stimulation.
Conclusions: Stimulation to the aBTLA (semantics) vs. SMG (phonological processing) generated transient reading disorders consistent with surface vs. phonological alexia. Dissociations between semantic and visual-orthographic aspects of reading were revealed by stimulation to the aBTLA vs. pBTLA. Taking these networks into account is important in epilepsy surgery.
Funding: This study is supported by KAKENHI: 22H02945 and 22K07537.
Behavior