P27-17 Paroxysmal EEG abnormalities and epilepsy in pervasive developmental disorders 1) Study on a large number of subjects

29th International Congress of Clinical Neurophysiology before the onset of the final word of each sentence and ending at 1200 ms after onset of this stimulus. Results: In TDA and TDC group, negative component about 400 ms after the onset of the final word of each sentence (N400) appeared clearly for incongruent sentences. Although TDC group also showed N400 for incongruent sentences, latency of N400 was prolonged that compared with that of TDA group. N400 for incongruent sentences was also observed in ASD group, however, larger variance of latency and amplitude for that component in ASD group than that in TDC group. Conclusion: These results suggested that children with ASD might have difficulty in comprehension of sentence context effectively. P27-16 Event-related potentials in persons with Asperger disorder A. Iwanami1 , Y. Okajima1 , Y. Kawakubo2 , H. Yamasue2 , C. Kanai1 , N. Kato1 1 Department of Psychiatry, Showa University School of Medicine, Japan, 2 Department of Neuropsychiatry, Faculty of Medicine, University of Tokyo, Japan Asperger disorder is a subtype of pervasive developmental disorders (PDD). The disorder is characterized by deficits in reciprocal social interaction, subtle impairment of verbal and nonverbal communication, and the presence of idiosyncratic isolated interests. Event-related potentials were recorded in 14 persons with Asperger disorder according to DSM-IV criteria during two auditory discrimination tasks, which were a standard oddball task and a distraction task similar to that of Grillon et al. Subjects were presented with a series of 300 auditory stimuli with an interstimulus interval of 1000 ms. In the oddball task, 85% of the stimuli were tones of 1 KHz, and the other 15% tones of 2 KHz. In the distraction task, 70% of the stimuli were tones of 1 KHz, 15% tones of 2 KHz, and the other 15% white noise (novel stimuli). The subjects were instructed to press a button as quickly as possible for the infrequent highpitch tones in both tasks. According to the international 10 20 system, the scalp electroencephalogram (EEG) was recorded with Ag/Ag-Cl disc electrodes at Fz, Cz, and Pz monopolarly, referred to linked earlobes. The responses to frequent and rare tones and novel stimuli with correct reactions were averaged separately. ERPs for target stimuli in the oddball task and for novel stimuli in the distraction task were analyzed. P300 was defined as the most positive peak between 250 and 500 ms poststimulus. Amplitudes were measured with respect to an average voltage during the 100 ms prestimulus. P300 amplitude for target stimuli in persons with Asperger disorder did not differ significantly from that in normal controls. In contrast, P300 amplitude for novel stimuli in persons with Asperger disorder was smaller. The results supported the view of an increased distractibility in persons with Asperger disorder. P27-17 Paroxysmal EEG abnormalities and epilepsy in pervasive developmental disorders 1) Study on a large number of subjects Y. Kawasaki1 , M. Shinomiya1 , M. Takayanagi1 , S.-I. Niwa2 1 Musashino Child Development Clinic, Japan, 2 Fukushima University, Japan Objective: Although many reports on paroxysmal EEG abnormalities and epilepsy among patients with pervasive developmental disorders (PDD) were made, the findings varied and still remain inconclusive. We worked on this theme with a large number of subjects. Methods: Subjects comprised 1624 PDD cases (1319 males, 305 females) between the ages of 3 to 41 with mean age of 12 years and 2 months. A total of 3872 EEG records were available for analysis among the 1624 cases. Results: 169 subjects (10.4%) had epilepsy. Epilepsy appeared most commomly at the age of 7 and during adolescence. The ratio of paroxysmal abnormalities changed with age-the ratio, which was 10 to 30% in early childhood, gradually increased and reached around 40% at the age of 7 and remained thereafter throughout their adolescence. The foci of paroxysms also changed with age. Paroxysma appeared at various foci in early childhood however those appearing in the frontal area gradually became prevalent, accounting for more than 50 to80% at the age of 11 and thereafter. Conclusions: PDD subjects most commonly developed epilepsy at the age of around 7 and during their adolescence. The subjects in their early childhood showed paroxysmal abnormalities at the various foci but many in their adolescence showed the ones appearing in the frontal area. We

S267 named this prevailing paroxysms in the frontal area among PDD patients in their adolescence as “Paroxysms at F”. Researchers reported various findings because their studies targeted different age groups. It is only natural for the studies with subjects in early childhood and in adolescence to reach different conclusions. P27-18 Paroxysmal EEG abnormalities and epilepsy in PDD 2) Study on subjects with follow-up and identification of paroxysmal origin in the brain by MEG Y. Kawasaki1 , M. Shinomiya1 , M. Takayanagi1 , S.-I. Niwa2 1 Musashino Child Development Cinic, Japan, 2 Fukushima University, Japan Objective: It is common to see changes in the foci of paroxysmal abnormalities with PDD patients in their early childhood as they grow older. We therefor extracted subjects with sufficients follow-up from study (1) to observe their paroxysmal abnormalities and epilepsy. MEG was performed on 12 of them to identify the origin of paroxysms. Methods: We attempted a detailed follow-up study on the subjects with EEG records covering all four periods of 5 years old, 6 9 years old, 10 14 years old, and 15 years old. The subjects included 92 individuals between the age of 15 and 36 (74 males and 18 females). A total of 782 records for 92 subjects were analyzed. MEG and EEG were recorded simultaneously and the current dipoles with the correlation coefficients of 0.985 and over in the MEG synchronized with paroxysms appearing EEG were superimposed on MRI images. Results: Of the 92 subjects, 38 had developed epilepsy. The foci of paroxysms were widely distributed in early childhood but this tendency disappeared as paroxysms in the frontal area (Paroxysm at F) became prevalent in adolescence. Paroxysms at the time of epilepsy onset also were widwly distributed in early childhood but Paroxysm at F gradually increased, overwhelmingly prevailing in adolescence. MEG records for the 12 subjects with Paroxysm at F identified the localization in the superior frontal gyrus and anterior cingulate gyrus for the most part and some in the orbital gyrus. Conclusions: It suggests that PDD patients have functional abnormality of the brain also in the regions mentioned above. P27-19 Atypical activity associated with self-related processing in pervasive developmental disorders T. Morita1 , H. Kosaka2 , S. Itakura3 , R. Kakigi1 , N. Sadato1 1 National Institute for Physiological Sciences, Okazaki, Japan, 2 Faculty of Medical Sciences, University of Fukui, Fukui, Japan, 3 Graduate School of Letters, Kyoto University, Kyoto, Japan Objectives: Previous behavioral studies have suggested that individuals with pervasive developmental disorders (PDD) have abnormal emotional response or self-awareness related to self-referential processing, but little is known about neurophysiological basis of impaired self-referential processing. Here, we aimed to investigate behaviors and neural activities associated with a self-referential processing in individuals with PDD, focusing on emotional and attentional aspects. Methods: We used functional MRI to measure brain activity in 15 individuals with PDD and 15 healthy individuals engaged in evaluation task, where they were asked to rate images of their own face (SELF) and those of others (OTHERS) according to how photogenic they appeared to be. After the scanning, the participants rated how embarrassed they felt upon viewing each face. Results: There was no significant difference in photogenic ratings and embarrassment ratings between PDD and control subjects. However, there was a difference in relationship between the embarrassment ratings and the photogenic ratings for own faces. While controls showed a strong relationship between two ratings, PDD subjects showed weaker relationship. For the MRI data, we performed region of interest (ROI) analysis based on functionally defined ROIs which was more strongly activated during evaluation of own faces compared to those of others in our previous study. The PDD group showed hypoactivation of cingulate cortex during the evaluation of own faces. Furthermore, the activation in the cingulated cortex was negatively correlated with the subscale for attention to detail in Autism-Spectrum Quotient (AQ), a measure of the extent of autistic traits. Conclusion: These results suggest that individuals with PDD would tend to focus exclusively on the physical aspect of external stimuli, not divide