Nanae Michida

Comparison of event related potentials with and without hypnagogic imagery.

Abstract It is hypothesized that when hypnagogic imagery occurs, an appropriate attention may allocate to the imagery, resulting in the allocation of attention to the external tone stimuli being diminished. N3 amplitude of event related potentials (ERP) obtained a significant difference between the conditions with and without imagery. Arousal level of behavior and electroencephalography were not different between the conditions, therefore it is interpreted that the decrease of the N3 amplitude during imagining reflects the diminution of the allocation of attention to the external tone stimuli. Another late component of ERP, P3, did not make clear peaks in this study despite a large time constant (τ= 3.2 s) used for EEG records.

Changes of amplitude and topographical characteristics of event-related potentials during the hypnagogic period.

In the previous study, during the vertex sharp wave period (hypnagogic EEG stage 4), negative components (N300, N550) were dominant at Fz and Cz in contrast to the positive component (P400) being prominent at the other areas, Pz, Oz, T5 and T6. There is no agreement regarding P400 properties during the hypnagogic period. In this study, using topographic mapping, we found that two negative components (N300, N550) and P400 independently increased their amplitude at the different areas of the scalp as arousal level lowered. The anterior negative components may reflect the information processing related to the K‐complex. The P400 may reflect other activities different from the K‐complex mechanism or P300 attention mechanisms.

Seat Lumbar Support Evaluation With ASPECT Manikin

Seat lumbar support is thought to be essential for seating comfort as it plays important role in the drivers fatigue during long term driving. We tried to evaluate the lumbar support performance objectively with Seat Pressure Distribution. First, the tolerance in the measurement was eliminated by application of ASPECT manikin that reproduced a human seating torso posture [1, 2]. Second, an analysis method to visualize the seat support balance on the human back was developed. Third, a hypothesis for the optimal support balance to minimize the fatigue was proposed according to the fatigue growing mechanisms. Examining the deviation of each seat result from the optimal support, the performances were quantitatively evaluated. In addition to that, the effect of the lumbar support adjuster was taken into consideration to predict the market evaluation more precisely.

Seat Lateral Support Evaluation With SAE Manikin

In this report, we proposed an objective evaluation method of the seat lateral support according to the mechanisms to create the performance differences that we reported previously [1]. First, we showed an effect of scrutinizing Seat Pressure Distributions change during vehicle turn to gain a quantitative index for explaining subjective evaluation results. Second, we showed the examples of the differences of the results according to the subjects and selected the best-correlated subject among them with a market survey result. Then, we contrived a loading condition to SAE manikin to reproduce the subjects Seat Pressure Distribution. Final, by a specific calculation of the Seat Pressure Distribution, the method to indicate the performance rating that had strong correlation with market survey was clarified.