Kunihiko Araki1, Kiyohito Terada2, Keiko Usui1, Naotaka Usui3, Yasukiyo Araki1, Koichi Baba3, Kazumi Matsuda3, Takayasu Tottori3, Yushi Inoue4. 1. Department of Neurology, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan. 2. Department of Neurology, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan. Electronic address: kyht-terada@umin.net. 3. Department of Neurosurgery, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan. 4. Department of Psychiatry, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Japan.
Abstract
OBJECTIVE: The basal temporal language area (BTL) is known to be involved in the semantic processing of language. To investigate the neural connectivity between BTL and the posterior language area (PL), we used cortico-cortical evoked potential (CCEP) technique. METHODS: Four patients with intractable epilepsy who underwent presurgical evaluation with subdural electrodes were examined. All patients were right-handed and left language dominance by Wada test. We directly stimulated 20 pairs of electrodes placed on BTL in patient 1-3, putative BTL in patient 4, and PL in patient 1-4. In patient 4, all electrodes on the left temporal basal area were stimulated. RESULTS: We could record 132 CCEP responses including 40 responses by the left basal temporal stimulation in patient 4. The waveforms from PL to BTL were triphasic, while those from BTL to PL were biphasic. The mean latency of the first negative peak (N1) was shorter at BTL (31.8-41.0ms; mean 35.1ms) than at PL (39.6-73.2ms; mean 52.3ms). CONCLUSIONS: We revealed the uneven bidirectional connection between BTL and PL. SIGNIFICANCE: We speculated that the two language areas are connected mainly through subcortical fibers from PL to BTL and through cortico-cortical fibers from BTL to PL, mediated by multisynaptic transmissions.
OBJECTIVE: The basal temporal language area (BTL) is known to be involved in the semantic processing of language. To investigate the neural connectivity between BTL and the posterior language area (PL), we used cortico-cortical evoked potential (CCEP) technique. METHODS: Four patients with intractable epilepsy who underwent presurgical evaluation with subdural electrodes were examined. All patients were right-handed and left language dominance by Wada test. We directly stimulated 20 pairs of electrodes placed on BTL in patient 1-3, putative BTL in patient 4, and PL in patient 1-4. In patient 4, all electrodes on the left temporal basal area were stimulated. RESULTS: We could record 132 CCEP responses including 40 responses by the left basal temporal stimulation in patient 4. The waveforms from PL to BTL were triphasic, while those from BTL to PL were biphasic. The mean latency of the first negative peak (N1) was shorter at BTL (31.8-41.0ms; mean 35.1ms) than at PL (39.6-73.2ms; mean 52.3ms). CONCLUSIONS: We revealed the uneven bidirectional connection between BTL and PL. SIGNIFICANCE: We speculated that the two language areas are connected mainly through subcortical fibers from PL to BTL and through cortico-cortical fibers from BTL to PL, mediated by multisynaptic transmissions.
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