간질성 뇌파의 시공간 패턴 분석 김 정 애 , 한 승 기 임 태 규 이 상 건 , 남 현 우 충북대학교 물리학과 김 정 애 , 한 승 기 충북대학교 물리학과 임 태 규 한국전자통신연구원, 인체정보연구부 이 상 건 , 남 현 우 서울대학교병원 신경과 .

간질(Epilepsy) ? 신경계의 변화에 의한 강한 발화 활동 -신경세포의 과도한 발화 -신경계의 변화에 의한 강한 동기화: 흥분성 영향의 증가, 억제성 영향의 감소 -간질성 발작 거동 뇌파의 변화, 뇌파 분석 간질 뇌파의 특징 추출, 간질 발현 시간 예측, 간질 위치 추정

Invasive EEG(Epileptic seizure) 간질뇌파(서울대병원 간질센터) Lateral Temporal Lobe Epilepsy(L-TLE) Depth EEG 32 channels, 200sec recording (interictal, ictal, postictal) -5subject EEG Electrodes Time(sec) channel Interictal ictal 5 4 3 2 1 10 9 8 7 6 15 14 13 12 11 20 19 18 17 16 21 22 23 24 25 26 27 28 29 30

Spatio-temporal Pattern Linear analysis: power spectrum -theta(3-7Hz), alpha(8-13Hz), beta(20-30Hz) Statistical analysis: Jensen-Shannon divergence - amplitude, peak time, variance, kurtosis Nonlinear analysis: mutual information -correlation time, correlation dimension Temporal changes, spatial dependence Correlations between different measures Robustness of pattern: inter-trials

Power spectrum analysis(1): Frequency band: theta(3~7Hz), alpha(8~13Hz), beta(20~30Hz) Total power 3~7hz 8~13hz 20~30hz Spectrum sum Power ratio spectrum sum: theta, alpha, beta is localization power ratio : -rhythm order : beta->alpha-> theta->total power

Power spectrum analysis: inter-trial variations sgo1 sgo2 sgo3 sgo4 sgo5 Time map of beta spectrum Time

Statistical analysis: Change in statistical properties of amplitude distribution boundary between two distributions? Jensen-Shannon divergence 분석구간

Statistical measures at JS-E maximum Temporal mapping of JS-E Plot of JS-divergence: JS-E Kurt STD Statistical measures at JS-E maximum Temporal mapping of JS-E Time of change in amplitude distribution Position of most dominant changes Statistical measures

Plot of JS-divergence: inter-trial variations sgo1 sgo2 sgo3 sgo4 sgo5 Time map of JS-E Time

Nonlinear analysis Nonlinear dynamics underlying the bursting neural activities Nonlinear measures characterizing the temporal behaviors Mutual information Average mutual information

Plot of correlation time: Time(sec) channel Correlation time(m sec) Temporal mapping of correlation time decrease in the correlation time during ital period no specific channel dependence Variability of the spatial mapping

Temporal maping of correlation time Plot of correlation time:inter-trial variations Temporal maping of correlation time Time sgo1 sgo2 sgo3 sgo4 sgo5

Comparison of temporal maps of JS-E , Beta, Correlation time sgo1 sgo2 sgo3 sgo4 sgo5 JS-E Beta Correl. time Partial overlapping between the temporal maps of JS-E and beta No similarity with the temporal map of correlation time

Correlation between inter-trials and different maps of JS-E, beta spectrum , and correlation time High inter-trial correlations for JS-E and beta spectrum Low inter-trial correlation for correlation time Correlations between different maps are weak

Neural network model of Epileptic seizure generation: CA3 in Hippocampus [Tateno,1998] Pyramidal cell (Δ) - Inhibitory inter-neuron () - Synaptic current Field current  Iaf : 해마 외부에서 가해지는 tonic input

신경 모형계(16x16)의 시공간 발화 패턴 Cpp=0.001 Cpp=0.003 Cpp=0.005 Cpp=0.008 time

STDP (Spike-Timing Dependent Plasticity) [G-q. Bi and M-m. Poo, 1998] Δt : tpost - tpre A+ : maximal synaptic strengthening A- : maximal synaptic weakening Normal hippocampus : A+ ~ A- Abnormal hippocampus : ?

A+와 A-에 따른 신경모형계의 거동 변화 (2) gaf=0.005uS, CPI=0.02uS, CIP=0.02uS

결론 및 논의 Spatio-temporal pattern analysis Power spectrum : JS-entropy : - spatio-temporal pattern of beta rhythm is more informative - lateral temporal lobe epilepsy is close to the hippocampus - beta rhythm is generated in the hippocampus JS-entropy : - earlier rise of JS entropy in several channels - the position of rises are consistent with diagnostic of the medical doctors - the shape of distribution function, es. kurtosis : seizure generation Mutual information : correlation time - short correlation time for ictal rhythm - non-specific map: no information on the localization Neural network model of seizure generation: - CA3 model + Spike-Timing Dependent Plasticity - unbalance between synaptic strengthening and weakining