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Selected Papers: Electroencephalogram and Clinical Neurophysiology
Event Related Potentials Evoked by Pure Tone and Linguistic Stimulation in Epileptic Children Kimiya Kon, M.D., Mayumi Nagai, M.D., Yasushi Yoshihara, M.D., Ritsuko Takahashi, M.D., Tsuneo Yagi, M.D., Koichiro Ike, M.D., Kazuhiro Haginoya, M.D. and Kazuie Iinuma, M.D. Department of Pediatrics, Tohoku University School of Medicine, Sendai
Introduction Event related potentials (ERPs) provide information about brain activity, even in the absence of behavioral data.’ Recently, the clinical application of ERPs became popular in children.6 An auditory discrimination task, which is the so-called oddball paradigm3 using attend tone stimuli that rarely and randomly occurs in a series of unattend and frequent stimuli of a different pitch, is often employed in these studies. We attempt to use meaningful words for stimulation of auditory ERPs in children, because younger children may be able to easily understand instruction of this examination and the difference of pure tone and linguistic word may lead to one elucidation of information processing function. This is a preliminary study of auditory ERPs evoked by pure tone and linguistic word stimulation in 20 epileptic children. Subjects and Methods Twenty patients (12 males and 8 females) of epilepsy were examined (mean age 14.3, SD 3.8, 12 localization related, 8 generalized). They had well controlled their attacks and had no problems in their school life. The ERPs were derived from the Fz, Cz, and Pz electrodes of the international 10-20 system. They were referred to linked earlobes with a forehead ground. An analysis time was 1,024 msec including 100 msec prior to the stimuli onset to establish a prevtimulus baseline, and the filter band-
pass was set between 0.5 and 30 Hz. Waveforms were averaged on-line by an ATAC 3700 (Nihon Kohden Co. Ltd., Tokyo, Japan) which controlled the artifact rejection. ERPs were elicited with a nontarget and target stimulus presented binaurally at 60 dB HL. The target stimuli occurred randomly as probability of 0.20 with an inter-stimuli interval of 2.0 sec. The subjects were instructed to listen to the auditory stimuli and push the button by their right hand whenever a target was perceived. A total of 15 artifact-free target stimulus trials were averaged. Experimental 1 (TB) employed target stimuli of a 2,000 Hz tone burst and nontarget stimuli of a 1,000 Hz tone burst. Experimental 2 (W) employed target stimuli of “A-KA” which means red in Japanese and nontarget stimuli of “ A - 0 which means blue in Japanese. These sounds were synthesized by a voice-maker with the same sound “A” and following the different sound “KA” or “0,” so the subjects could discriminate each stimulus by listening to the second vocal sound. Results Waveforms for each electrode for each condition were analyzed in the same fashion. The Ntl-Nt2-Pt3 complex was isolated for condition TB. On the other hand, the Nwl-Nw2-Nw3-Pw3 complex was isolated for condition W (Fig. 1). The Nw3 corresponds to Nt2, and these components are called mismatch negativity. The distribution of Nw3 or Nt2 is predominantly over the frontal region. The mean peak latency values of N1, N2, N3 and P3 for the Pz electrode are presented in Table 1. The Pw3 latency was significantly later than the Pt3 latency ( t = 10.56, p
Selected Papers: Electroencephalogram and Clinical Neurophysiology
Event Related Potentials Evoked by Pure Tone and Linguistic Stimulation in Epileptic Children Kimiya Kon, M.D., Mayumi Nagai, M.D., Yasushi Yoshihara, M.D., Ritsuko Takahashi, M.D., Tsuneo Yagi, M.D., Koichiro Ike, M.D., Kazuhiro Haginoya, M.D. and Kazuie Iinuma, M.D. Department of Pediatrics, Tohoku University School of Medicine, Sendai
Introduction Event related potentials (ERPs) provide information about brain activity, even in the absence of behavioral data.’ Recently, the clinical application of ERPs became popular in children.6 An auditory discrimination task, which is the so-called oddball paradigm3 using attend tone stimuli that rarely and randomly occurs in a series of unattend and frequent stimuli of a different pitch, is often employed in these studies. We attempt to use meaningful words for stimulation of auditory ERPs in children, because younger children may be able to easily understand instruction of this examination and the difference of pure tone and linguistic word may lead to one elucidation of information processing function. This is a preliminary study of auditory ERPs evoked by pure tone and linguistic word stimulation in 20 epileptic children. Subjects and Methods Twenty patients (12 males and 8 females) of epilepsy were examined (mean age 14.3, SD 3.8, 12 localization related, 8 generalized). They had well controlled their attacks and had no problems in their school life. The ERPs were derived from the Fz, Cz, and Pz electrodes of the international 10-20 system. They were referred to linked earlobes with a forehead ground. An analysis time was 1,024 msec including 100 msec prior to the stimuli onset to establish a prevtimulus baseline, and the filter band-
pass was set between 0.5 and 30 Hz. Waveforms were averaged on-line by an ATAC 3700 (Nihon Kohden Co. Ltd., Tokyo, Japan) which controlled the artifact rejection. ERPs were elicited with a nontarget and target stimulus presented binaurally at 60 dB HL. The target stimuli occurred randomly as probability of 0.20 with an inter-stimuli interval of 2.0 sec. The subjects were instructed to listen to the auditory stimuli and push the button by their right hand whenever a target was perceived. A total of 15 artifact-free target stimulus trials were averaged. Experimental 1 (TB) employed target stimuli of a 2,000 Hz tone burst and nontarget stimuli of a 1,000 Hz tone burst. Experimental 2 (W) employed target stimuli of “A-KA” which means red in Japanese and nontarget stimuli of “ A - 0 which means blue in Japanese. These sounds were synthesized by a voice-maker with the same sound “A” and following the different sound “KA” or “0,” so the subjects could discriminate each stimulus by listening to the second vocal sound. Results Waveforms for each electrode for each condition were analyzed in the same fashion. The Ntl-Nt2-Pt3 complex was isolated for condition TB. On the other hand, the Nwl-Nw2-Nw3-Pw3 complex was isolated for condition W (Fig. 1). The Nw3 corresponds to Nt2, and these components are called mismatch negativity. The distribution of Nw3 or Nt2 is predominantly over the frontal region. The mean peak latency values of N1, N2, N3 and P3 for the Pz electrode are presented in Table 1. The Pw3 latency was significantly later than the Pt3 latency ( t = 10.56, p
