Intranasal Oxytocin Increases Perceptual Salience of Faces in the Absence of Awareness.

OBJECTIVE: The neuropeptide oxytocin has been found to improve human social cognition and promote prosocial behavior. However, it is still unclear about the mechanisms underlying these effects of oxytocin on neural processes, such as visual perception and awareness. Especially, it is still unclear whether oxytocin influences perceptual salience of social stimuli in the absence of awareness. METHODS: In a randomized double-blind, placebo-controlled trial we applied an interocular suppression paradigm and eye tracking methods to investigate the influence of intranasally administered oxytocin on perceptual salience of social stimuli. Suppression times and pupillometric data were measured during subjects being presented with gradually introduced pictures of social stimuli (neutral expression faces) or nonsocial stimuli (grayscale watch pictures) that were suppressed and invisible in 10 men who were administered 24 IU oxytocin and 10 men who were administered a placebo. RESULTS: The results demonstrated that the oxytocin group perceived social stimuli more quickly accompanied by subsequent larger increasing pupil diameter than nonsocial stimuli, indicating an increased unconscious salience of social stimuli. CONCLUSION: These findings provided new insights into oxytocin's modulatory role to social information processing, suggesting that oxytocin might enhance attentional bias to social stimuli even after removal of awareness.

Regulation of trace elements and redox status in striatum of adult rats by long-term aerobic exercise depends on iron uptakes.

We investigated the effects of aerobic exercise (AE) on trace element contents and redox status in the striatum of rats with different diet iron. Weaned female rats were randomly fed with iron-adequate diet (IAD), iron-deficient diet (IDD), and iron-overloaded diet (IOD). After feeding their respective diet for 1 month, the rats fed with same diet were divided into swimming and maintaining sedentary (S) group. After 3 months, the non-heme iron (NHI), Mn, Cu, and Zn in the striatum were measured. Meanwhile, malonaldehyde acid (MDA), total superoxide dismutase activity, hydroxyl radical scavenging activity, and total antioxidant capacity were also analyzed. As compared with respective S rats, Mn, Cu, and Zn contents were significantly decreased in IDDE, but no significantly changes could be seen in IADE or IODE. A negative correlation of NHI with Cu contents in IDDE and positive correlations of NHI with Cu, or Zn contents in IADE, or with Mn or Cu contents in IODE were observed. In addition, striatum MDA was significantly decreased and anti-oxidative variables were increased in IODE compared to IODS. Our results suggest that the modification of trace elements and redox status in the striatum of rats caused by AE depends on dietary iron contents and that AE may also regulate the metabolic relationship of iron storage with other trace elements.