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84. Human cerebral somatosensory cortex response to mechanical stimulation using a new non-magnetic device
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Society Proceedings / Clinical Neurophysiology 120 (2009) e147–e180
architecture than the lower IRLS group. However, several patients having severe RLS by IRLS had no LMs during the SIT. Conclusions: The SIT can be useful as one of evaluation method of RLS, but its important to diagnose synthetically with clinical symptoms and family history. doi:10.1016/j.clinph.2009.02.088
83. Spectral analysis of ictal high frequency oscillations in intracranial EEG of patients with mesial temporal lobe epilepsy— Fumihiro Nakamura, Kiyohito Terada, Naotaka Usui, Keiko Usui, Kouichi Baba, Takayasu Tottori, Kazumi Matsuda, Shigeru Fujitani, Yushi Inoue, Miyako Yamaguchi (National Epilepsy Center, Shizuoka, Japan) The aim of this study was to investigate the time series and space analysis of ictal high-frequency oscillations (HFOs) near the seizure onset area in mesial temporal lobe epilepsy (mTLE). All patients with mTLE were planned to undergo the intracranial EEG recording for presurgical evaluation. Depth and subdural macro-electrodes was inserted and digital EEG monitoring was done to detect ictal EEG. Besides routine procedure, EEG at 1000 Hz sampling was recorded for about 1 day. By visual inspection, HFOs more than 200 Hz was found in 41 seizures of 10 patients. For 60 seconds immediately before seizures, signals of all channels were analyzed with MBFA program. Almost all HFOs in 33 seizures were detected from channels around hippocampus or parahippocampal gyrus in the resection side. HFOs periodically appeared, but spectrum was consecutively found from 100 to 300 Hz with some prominent peaks. In many cases, HFOs evolved in occurrence rate and spectral power in a discontinuous manner. In three cases, HFOs seemed to be independent or lost during seizure propagation. In a case, HFOs showed different pattern in occurrence rate and spectrum between SPSs and CPSs. HFOs seemed to be related to the epileptogenic zone, but not expressed epileptogenesis directly. doi:10.1016/j.clinph.2009.02.089
84. Human cerebral somatosensory cortex response to mechanical stimulation using a new non-magnetic device—Hikmat Hadoush 1, Ken Inoue 2, Kazuyoshi Nakanishi 3, Hiroshi Kurumadani 1, Toru Sunagawa 1, Mitsuo Ochi 3 (1 Graduate School of Health Science, Hiroshima University, Japan, 2 Hiroshima Prefecture Hospital, Japan, 3 Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan) The present study examined the sensory cortex responses elicited by on/off mechanical stimuli to the human glabrous skin. Magnetoencephalography (MEG) was used to measure the somatosensory evoked fields (SEFs) elicited by touch and removal the glabrous skin of index finger using a new non-magnetic mechanical stimulator. A surprising finding was that activation of ipsilateral primary somatosensory cortex SI (iSI) was detected at touch stimuli in all subjects (n = 7). The contralateral SI (cSI) responses were detected at touch (tSEFs) and removal (rSEFs) stimuli. In this study, the strength amplitude of tSEFs was larger than those of rSEFs (p < 0.05). In addition, touch stimuli was able to activate the ipsilateral secondary somatosensory cortex (iSII), whereas removal stimuli was not. In conclusion, we report here a novel finding that non-invasive MEG recordings revealed activation of iSI at touch stimuli in all of our healthy subjects. Also, we introduce new non-magnetic tactile stimulator that allows
a clear and a replicable recording of SEFs in cSI, iSI and iSII, without the need of electrical stimuli, during the MEG study. doi:10.1016/j.clinph.2009.02.090
85. Feature extraction of EEG waveforms by directed information analysis during mis-operation of the brain–computer interface system—Katsuhiro Inoue, Miyo Taniguchi, Tomonari Yamaguchi (Kyushu Institute of Technology, Iizuka, Japan) For the BCI (Brain–Computer Interface) system, the machine operation based on the system output should be executed on the safety side. Therefore, a fail-safe function is indispensable. In order to construct such function, it is necessary to identify whether the machine operation based on the feature extracted from EEGs is in accordance with the subject’s will or not. In this study, we tried to extract features (e.g. amount of transmission, delay of transmission and the direction of transmission) concerned with error potential by using the directed information analysis. In experiments, subjects were instructed to imagine right-hand movement or left-hand movement. ‘Pseudo-feedbacks’ (direction different from the subject’s will or same direction as the subject’s will) were then presented to the subjects. The incidence ratio of correct feedback and wrong feedback was set to be 8:2. EEGs were recorded from 20 electrode sites including midline (Fz, Cz, Pz, and Oz) sites of the international 10–20 system. Sampling frequency was 512 Hz. The information flow from occipital region to frontal region has clearly been shown when each feedback against one’s will was displayed to the subjects who had already been skillful for BCI system. doi:10.1016/j.clinph.2009.02.091
86. The effects of illusory depth perception on human visual evoked potentials—Shu Omoto, Yoshiyuki Kuroiwa, Chuanwei Wang, Yasuhisa Baba, Shigeru Koyano, Yume Suzuki (Yokohama City University, Yokohama, Japan) Visual evoked potentials (VEPs) were recorded in a non-illusory task I and an illusory task II, to investigate the cerebral activity which correlates with an illusory depth perception. Each stimulus consisted of smaller and larger squares with geometrical segregation. Stimuli A/B were presented alternatively in task I and were perceived as 2-dimensional flat images. Stimuli C/D were presented alternatively in task II and were perceived as 3-dimensional images: a convex and a concave figure. The first clearly observable negative peak (C1) commonly reflects an excitation of the primary visual cortex (V1) activated by perception of geometrical segregation. P1, P1/N1, and P2 amplitudes during task II with illusory perception of depth images were significantly larger than during task I without perception of depth images. P1 and P1/N1 amplitude differences between our two tasks can be explained by the effects of task differences, with or without illusory depth perception, since previous studies revealed that perception of depth images is significantly reflected in P1 and N1 amplitudes. The role of the P2 component still remains unknown. The reason for increased P2 amplitude during task II with illusory perception of depth images remains unknown. doi:10.1016/j.clinph.2009.02.092
Society Proceedings / Clinical Neurophysiology 120 (2009) e147–e180
architecture than the lower IRLS group. However, several patients having severe RLS by IRLS had no LMs during the SIT. Conclusions: The SIT can be useful as one of evaluation method of RLS, but its important to diagnose synthetically with clinical symptoms and family history. doi:10.1016/j.clinph.2009.02.088
83. Spectral analysis of ictal high frequency oscillations in intracranial EEG of patients with mesial temporal lobe epilepsy— Fumihiro Nakamura, Kiyohito Terada, Naotaka Usui, Keiko Usui, Kouichi Baba, Takayasu Tottori, Kazumi Matsuda, Shigeru Fujitani, Yushi Inoue, Miyako Yamaguchi (National Epilepsy Center, Shizuoka, Japan) The aim of this study was to investigate the time series and space analysis of ictal high-frequency oscillations (HFOs) near the seizure onset area in mesial temporal lobe epilepsy (mTLE). All patients with mTLE were planned to undergo the intracranial EEG recording for presurgical evaluation. Depth and subdural macro-electrodes was inserted and digital EEG monitoring was done to detect ictal EEG. Besides routine procedure, EEG at 1000 Hz sampling was recorded for about 1 day. By visual inspection, HFOs more than 200 Hz was found in 41 seizures of 10 patients. For 60 seconds immediately before seizures, signals of all channels were analyzed with MBFA program. Almost all HFOs in 33 seizures were detected from channels around hippocampus or parahippocampal gyrus in the resection side. HFOs periodically appeared, but spectrum was consecutively found from 100 to 300 Hz with some prominent peaks. In many cases, HFOs evolved in occurrence rate and spectral power in a discontinuous manner. In three cases, HFOs seemed to be independent or lost during seizure propagation. In a case, HFOs showed different pattern in occurrence rate and spectrum between SPSs and CPSs. HFOs seemed to be related to the epileptogenic zone, but not expressed epileptogenesis directly. doi:10.1016/j.clinph.2009.02.089
84. Human cerebral somatosensory cortex response to mechanical stimulation using a new non-magnetic device—Hikmat Hadoush 1, Ken Inoue 2, Kazuyoshi Nakanishi 3, Hiroshi Kurumadani 1, Toru Sunagawa 1, Mitsuo Ochi 3 (1 Graduate School of Health Science, Hiroshima University, Japan, 2 Hiroshima Prefecture Hospital, Japan, 3 Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan) The present study examined the sensory cortex responses elicited by on/off mechanical stimuli to the human glabrous skin. Magnetoencephalography (MEG) was used to measure the somatosensory evoked fields (SEFs) elicited by touch and removal the glabrous skin of index finger using a new non-magnetic mechanical stimulator. A surprising finding was that activation of ipsilateral primary somatosensory cortex SI (iSI) was detected at touch stimuli in all subjects (n = 7). The contralateral SI (cSI) responses were detected at touch (tSEFs) and removal (rSEFs) stimuli. In this study, the strength amplitude of tSEFs was larger than those of rSEFs (p < 0.05). In addition, touch stimuli was able to activate the ipsilateral secondary somatosensory cortex (iSII), whereas removal stimuli was not. In conclusion, we report here a novel finding that non-invasive MEG recordings revealed activation of iSI at touch stimuli in all of our healthy subjects. Also, we introduce new non-magnetic tactile stimulator that allows
a clear and a replicable recording of SEFs in cSI, iSI and iSII, without the need of electrical stimuli, during the MEG study. doi:10.1016/j.clinph.2009.02.090
85. Feature extraction of EEG waveforms by directed information analysis during mis-operation of the brain–computer interface system—Katsuhiro Inoue, Miyo Taniguchi, Tomonari Yamaguchi (Kyushu Institute of Technology, Iizuka, Japan) For the BCI (Brain–Computer Interface) system, the machine operation based on the system output should be executed on the safety side. Therefore, a fail-safe function is indispensable. In order to construct such function, it is necessary to identify whether the machine operation based on the feature extracted from EEGs is in accordance with the subject’s will or not. In this study, we tried to extract features (e.g. amount of transmission, delay of transmission and the direction of transmission) concerned with error potential by using the directed information analysis. In experiments, subjects were instructed to imagine right-hand movement or left-hand movement. ‘Pseudo-feedbacks’ (direction different from the subject’s will or same direction as the subject’s will) were then presented to the subjects. The incidence ratio of correct feedback and wrong feedback was set to be 8:2. EEGs were recorded from 20 electrode sites including midline (Fz, Cz, Pz, and Oz) sites of the international 10–20 system. Sampling frequency was 512 Hz. The information flow from occipital region to frontal region has clearly been shown when each feedback against one’s will was displayed to the subjects who had already been skillful for BCI system. doi:10.1016/j.clinph.2009.02.091
86. The effects of illusory depth perception on human visual evoked potentials—Shu Omoto, Yoshiyuki Kuroiwa, Chuanwei Wang, Yasuhisa Baba, Shigeru Koyano, Yume Suzuki (Yokohama City University, Yokohama, Japan) Visual evoked potentials (VEPs) were recorded in a non-illusory task I and an illusory task II, to investigate the cerebral activity which correlates with an illusory depth perception. Each stimulus consisted of smaller and larger squares with geometrical segregation. Stimuli A/B were presented alternatively in task I and were perceived as 2-dimensional flat images. Stimuli C/D were presented alternatively in task II and were perceived as 3-dimensional images: a convex and a concave figure. The first clearly observable negative peak (C1) commonly reflects an excitation of the primary visual cortex (V1) activated by perception of geometrical segregation. P1, P1/N1, and P2 amplitudes during task II with illusory perception of depth images were significantly larger than during task I without perception of depth images. P1 and P1/N1 amplitude differences between our two tasks can be explained by the effects of task differences, with or without illusory depth perception, since previous studies revealed that perception of depth images is significantly reflected in P1 and N1 amplitudes. The role of the P2 component still remains unknown. The reason for increased P2 amplitude during task II with illusory perception of depth images remains unknown. doi:10.1016/j.clinph.2009.02.092