Parenting plays a critical role in the infant’s survival and optimal development, as well as in the parent-infant attachment. The parent-infant relationship provides infants with their first social environment, forming templates to interact with others. In this review, we focus on neuroimaging studies of human maternal brain associated with the development of mother-infant relationship. First, we review the functional and structural changes in the mother’s brain during the early postpartum period. Second, we discuss the neural basis of maternal love, in which the orbitofrontal cortex integrates the reward and interoceptive processing systems, which suggests that a mother’s infant is not only a reward, but also functions to protect the mother's life through the production of homeostatic emotions in the mother. Third, we discuss the maternal brain including how the orbitofrontal cortex might possibly regulate maternal stress during the “terrible twos”. Maternal stress adaptations are important not only for the maternal behavior, but also for the mother’s well-being and mental health. Finally, we focus on the long-term effects of the early experience of parental care on the infant’s brain function, including those associated with later parenting and how maternal brain might shape the infant’s current and future brain.

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In this study, we investigated skin thermosensitivity in 10 female subjects (22.8±2.5 years old) to address various issues related to air-conditioned environments, focusing on menstrual cycle phase (follicular, ovulatory, luteal) and related hormones. Warm and cool thresholds in each stage of the menstrual cycle were measured in an experimental room with air temperature 28°C and relative humidity 50%. It was concluded that cold sensitivity was relatively low in the luteal phase. Furthermore, the results implied that progesterone affected cold sensitivity, with cold sensitivity becoming less acute with higher progesterone. However, it should be noted that women have higher skin thermosensitivity than men, regardless of menstrual cycle phase.

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Nocturnal light-induced melatonin suppression (NLMS) is well known, but few studies have investigated NLMS with respect to the energy of red, green, and blue components separately or the ratio of each component’s energy to the total energy of polychromatic light. The aim of this study was to elucidate the relationships of NLMS with blue light energy in polychromatic light and with monochromatic blue light energy. A difference in NLMS was found between monochromatic and polychromatic light at the same energy of blue light. This finding implies that NLMS might be affected not only by blue light energy but also by green and/or red light energy in polychromatic light.

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Red-, green-, and blue-colored paper stimuli were used to investigate the positive/negative emotions caused by looking at these colors in relation to the simultaneously recorded brain activity. The left lateral activity on electroencephalography (EEG), mental task performance, and the evaluation of color preference by the eight adult subjects were used as indexes. The results showed greater left lateral activity in the alpha band during the closed-eye resting period right after the subjects looked at red compared to the corresponding blue and green conditions. A significant positive correlation was revealed between the color preference evaluations and the left lateral activities, and a significant negative correlation was observed between the color preference evaluations and the activity at occipital regions during the closed-eye resting period.

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The present study investigated whether moving the front extremity forward over the center of mass (touch down distance; TD) at foot contact or moving the rear extremity backward at foot release (release distance; RD) affects the elongation of step length (SL) in the elderly. 18 older individuals (mean age, 83.6±8.0 years) living in a geriatric health services facility. The positively linear coefficient was found TD and RD in relation to walking speed. However, the increase in TD was caused by a diminished forward trunk flexion angle at foot contact. On the other hand, these results suggest that the increase in RD was associated with the hip extension angle, because the diminished forward trunk flexion angle at foot release was caused by the shortening of RD.

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