Search

A non-contact tactile stimulation system using a time-varying magnetic field was developed. The system comprises a control unit, power unit, output unit, and actuator. The control unit adjusts stimulation parameters, particularly the signal intensity and frequency. The power unit produces high voltages for generating the magnetic field, whereas the output unit transmits the energy generated according to the signal from the control unit to the actuator. A spiral coil actuator generates the magnetic field. To validate the effectiveness of the system, preliminary experiments on 10 male adults without neurological disorders (23.2 ± 3.05 years) were conducted. Magnetic field stimuli were presented to the right palm of the subjects at three different frequencies (10, 30, and 50 Hz), and corresponding electroencephalogram (EEG) signals were measured simultaneously. Event-related potential (ERP) analysis showed that N100 and P300 components were identified in somatosensory areas. Subjective evaluations revealed that feelings such as “tingling,” “trembling,” “tapping,” and “percussing” were induced. Moreover, as the stimulus frequency changes, differences may occur in induced feeling. The system uses a time-varying magnetic field, which not only induces tactile stimulation without contact but also has trans-object characteristics that can present tactile sensations, even when there is an obstacle between an actuator and skin.

This study aimed to compare the cognitive performance and event-related potential (ERP) patterns between females who have given birth (parous) and those who have not (nulliparous). A total of 50 female participants, including 27 who were parous (33.2 ± 3.2 years) and 23 who were nulliparous (30.8 ± 2.3 years), were recruited. Only parous females who were ≤36 months postpartum (17.7 ± 8.1 months) were included. To compare the cognitive performance between the two groups, we presented the 3-back task (a working memory task) and compared the accuracy rate (%) and reaction time (ms) between the groups. Electroencephalogram (EEG) signals were simultaneously recorded and the ERP patterns at Fz, Cz, and Pz, which are highly associated with the 3-back task, were analyzed. From the ERP patterns, we extracted N100, P300, P600, P300 peak-to-peak (P300p_p), and P600 peak-to-peak (P600p_p). There were no significant between-group differences in terms of accuracy rate, reaction time, or ERP components (N100, P300, P600, P300p_p, or P600p_p) at the three sites (Fz, Cz, and Pz). Since this study, using meaningful objective data, did not show that parity was significantly correlated with cognitive performance ability and ERP patterns, childbirth does not appear to influence cognitive decline.