休止時間を含んだ刺激方法における3-D SEFの刺激周波数-位相特性の検討(生体磁気・医療応用)

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A three-dimensional magnetic measurement of somatosensory evoked fields (SEFs) by electric stimulus to the right thumb for five normal subjects was carried out, using a three-dimensional second-order gradiometer connected to 39-channel SQUIDs, which can detect magnetic field components perpendicular to the scalp (Br) and tangential to the scalp (Bθ, Bφ) simultaneously. To discuss the relationship between the phase lag of SEFs and stimulus repetition frequency (SRF), the delay time of a component synchronous with the SRFs (stimulation was 2 to 7 train variety with 3.0 to 30.3 Hz, having a recovery period of 500 ms) was calculated by the convolution of the reference signal and the SEF wave (BPF : 1-40 Hz). The phase lag characteristic to the SRF differed in three ranges. Dominant slope appeared for two ranges (blow 8 Hz, 8 to 20 Hz) in all magnetic components. Dominant slope did not obtained in the range of more than 20 Hz SRF to the transient SEF waveforms. However, the dominant slope was obtained in the steady-state waveforms. We tested results for significance of the linear regression slope (β≠0, P<0.05).
2005-04-01