How do babies know their friends and foes?

The study of infant social cognition is the study of how human infants acquire information about people. By examining infants’ sensory abilities and the stimulus characteristics of people, research can determine what information is available to infants from their social world. We can then consider what social environments are appropriate for infants of different ages. This paper examines the sociocognitive competencies of human infants during the first 6 months of their lives and asks how these competencies are functional in the daily social ecology of the human infant. Select examples of research with other species are used to illustrate how the adaptive significance of sociocognitive abilities could be more fruitfully explored in studies of human infancy. Lonnie R. Sherrod is Vice President for Program at the William T. Grant Foundation. Formerly, he was Assistant Dean at the Graduate Faculty of the New School for Social Research and before that, Staff Associate at the Social Science Research Council. He received a Ph.D. in Developmental Psychology from Yale University in 1978, an M.A. in Biology from the University of Rochester in 1974; and a B.A. in Zoology and Psychology from Duke University in 1972. He has taught at New York University and the New School and has published numerous articles and edited volumes on infant social cognition, on adolescence, and on child development from a life-span and biosocial perspective. Examples includeInfant Social Cognition (1981), edited with Michael Lamb;The Life Course and Human Development: Multidisciplinary Perspectives (1986), edited with Aage B. Sorensen and Franz E. Weinert; and “Changes in Children’s Social Lives and the Development of Social Understanding” authored with Judith Dunn (1988), in E.M. Hetherington, M. Perlmutter, and R. Lerner (eds).,Child Development in Life-Span Perspective.     

State transitions in the statistically stable place cell population correspond to rate of perceptual change

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Cytokinin: perception,signal transduction,and role in plant growth and development

Cytokinins are essential hormones for the proper growth and development of plants. They exert their actions through the phosphorylation of two-component signaling factors. The two-component elements in cytokinin signaling display not only overlapping, but also specific functions throughout a life cycle. These elements regulate the development of shoots, roots, and inflorescence meristems inArabidopsis; shoot meristems in rice; and nodule formation in the lotus. They are also involved in interactions between plants and pathogens. In this review, we examine the mechanism for signaling events initiated by cytokinins inArabidopsis.     

Ultrasonic Signal Competition Between Male Wax Moths

Pair formation in the lesser wax moth, Achroia grisella (Lepidoptera: Pyralidae), is effected by male ultrasonic signals that are attractive to receptive females within 1-2 m. The males typically aggregate in the vicinity of the larval food resource, honeybee colonies, and signal for 6-10 h each night. Females are known to choose males on a relative basis and evaluate primarily three signal characters: signal rate (SR), loudness (peak amplitude; PA), and asynchrony interval (AI), a temporal feature reflecting the time interval between signals produced by the left and right tymbals. We conducted a series of experiments to investigate whether and how A. grisella males modify their signals in the presence of neighboring signalers. When separated by <40 cm, males increase their SRs by 3-6% upon perceiving a neighbor's signals, but they do not alter their PAs or Als. Increased SRs continue for 5-10 min and are more pronounced in males that are silent at the time they perceive their neighbor. By increasing its SR, a male improves the likelihood of matching or exceeding its neighbor's SR and may thereby compete more effectively for local females. SR increases are energetically demanding, though, and their brief duration and occurrence primarily at the beginning of signaling bouts may be the most prudent allocation of a male's limited energy reserves.     

视觉皮层下通路与拓扑知觉

研究表明，视觉通路除了经典的视觉皮层通路外，还有一条“古老的”、快速的皮层下通路负责在有意识和无意识状态下快速处理与情绪相关的信息。皮层下视觉通路由上丘、枕核和杏仁核组成，而且不经过初级视觉皮层。我们前期研究表明，初级视觉皮层与拓扑知觉信息加工没有关系，而皮层下视觉通路负责处理视觉拓扑信息。基于这些发现，我们认为，在早期视觉中，大脑检测涉及生命攸关的信号，这些信号告诉大脑：环境中有物体出现或消失，使大脑进入警戒状态，这对物种的生存至关重要。因此，在早期视觉中，需要检测的要素只是物体的“出现”和“消失”，而不是“纹理”、“形状”等。“出现”和“消失”都是拓扑特征的变化。拓扑感知和皮层下视觉通路的存在可能是早期预警的神经基础。在灵长类动物中，视网膜外周区域主要由视杆细胞构成，该区域接收的视觉信息主要通过皮层下视觉通路进行处理；视网膜中心区域（即中央凹）主要由视锥细胞构成，视觉空间分辨率变得非常高，该区域视觉信息处理主要是由视觉皮层负责。研究表明，由视杆细胞构成的视网膜是个“古老”结构，在1亿多年前就出现了；而视锥细胞构成的视网膜类型较为“年轻”，在5 000万年前才出现。所以，我们的视网膜从“古老”结构演化到“年轻”结构至少用了5 000万年的时间，它是由一个古老结构和一个年轻结构共同组成的“嵌合体”。当我们讨论皮层下通路存在的意义时，我们也应该结合皮层通路的功能来统一考虑。