Speculations on vitamin K, VKORC1 genotype and autism.

Humans vary in the gene that encodes for Vitamin K epoxide reductase complex (VKORC1). Recent research has documented the protective effect of Vitamin K on neural cells and its role in maintaining normal neural development. Of interest, specific neural effects of Vitamin K overlap with key brain development aberrations, including those associated with autism. Furthermore, Vitamin K protects against oxidative stress associated with toxic exposure. Research on the neural effects is reviewed, and a small sample of severely autistic children of Somali descent residing in the Minneapolis/St. Paul area of Minnesota were genotyped and found to have a higher than expected genetic substitution that results in reduction in the efficiency of the Vitamin K cycle. The possibility that this genetic difference could play an etiological role in the development of autism is considered.

When in doubt, do it both ways: brain evidence of the simultaneous activation of conflicting motor responses in a spatial stroop task.

Response competition is often considered an important contributor to the delayed reaction to stimuli for which physical and semantic information are in conflict ("Stroop" effect). Response competition implies that brain areas associated with correct and incorrect responses (e.g., left and right motor cortices) should be simultaneously activated in conflict conditions. However, there is at present little direct evidence of this phenomenon, in part because of the paucity of brain imaging techniques that can independently monitor the time course of activation of adjacent brain areas, such as the motor areas. In the present study, we show that the event-related optical signal (EROS) can provide these types of data. The results confirm the prediction that conflict trials elicit simultaneous activation of both motor cortices, whereas nonconflict trials elicit brain activity only in the contralateral motor cortex. These data support a parallel view of the human information processing system.

Estrogens and relationship jealousy.

The relation between sex hormones and responses to partner infidelity was explored in two studies reported here. The first confirmed the standard sex difference in relationship jealousy, that males (n=133) are relatively more distressed by a partner's sexual infidelity and females (n=159) by a partner's emotional infidelity. The study also revealed that females using hormone-based birth control (n=61) tended more toward sexual jealousy than did other females, and reported more intense affective responses to partner infidelity (n=77). In study two, 47 females were assessed four times across one month. Patterns of response to partner infidelity did not vary by week of menstrual cycle, but significant relations between salivary estradiol level and jealousy responses were obtained during the time of rising and high fertility risk. The implications, at least for females, are that any evolved psychological, affective, or behavioral dispositions regarding reproduction-related relationships are potentially moderated by estradiol, and that the use of synthetic hormones may disrupt this relation.

Memory-driven processing in human medial occipital cortex: an event-related optical signal (EROS) study.

Memory-driven processing in medial occipital areas (Area V1 and immediately adjacent structures) was investigated noninvasively using the event-related optical signal (EROS). Subjects viewed two letter stimuli presented in the left and right hemifields, respectively. They then viewed a centrally presented test letter and had to indicate whether this letter was the same as either of the letters presented earlier. The initial EROS response to the test stimulus in medial occipital areas (latency: 50-150 ms) was unilaterally suppressed in the hemisphere previously exposed to the same stimulus. This finding suggests that medial occipital cortex activity is modulated by a rapidly adapting hemispheric-specific pattern recognition mechanism.