ABSTRACT
The skin forms a continuous, highly organized and responsive interface between the organism and the environment. The skin is a sensory organ that functions in many ways as a ‘‘smart material,’’ i.e., a material that shows an oriented response to an external stimulus, e.g., heat, friction, sunlight, water, and chemicals (1). In this view, the skin functions as a sensory signal transducer closely linked to the regulation of central processes. The rate of change of skin temperature, for example, controls the thermoregulatory response to cold (2). Specific receptors in the skin, sensitive to mechanical stimuli, are critical for survival. Researchers are beginning to identify the signaling proteins involved in this transduction (3). Psychological stress due to environmental overcrowding is associated with a delay in skin barrier recovery in mice, an effect attributed to increased production of glucocorticoids (4). Skin-to-skin contact immediately following birth results in increased temperature and blood glucose levels, compared to swaddling next to the mother (5). Tactile stimulation via repeated stroking increases circulating lactate levels by 200% in the neonatal rat model (6). These examples indicate the intimate connection of the skin and the environment. They support an important role of the skin in actively modulating the interaction between the environment and underlying dermal, neural, and neuroendocrine control systems. In this view, the skin constitutes a prototypical smart material interface between the organism and the environment. This chapter explores this concept in the context of the newborn infant.
