How thermal, mechanical and chemical stimuli applied to the skin are transduced into signals transmitted by peripheral neurons to the CNS is an area of intense study. Several studies indicate that transduction mechanisms are intrinsic to cutaneous neurons and that epidermal keratinocytes only modulate this transduction. Using mice expressing channelrhodopsin (ChR2) in keratinocytes we show that blue light activation of the epidermis alone can produce action potentials (APs) in multiple types of cutaneous sensory neurons including SA1, A-HTMR, CM, CH, CMC, CMH and CMHC fiber types. In loss of function studies, yellow light stimulation of keratinocytes that express halorhodopsin reduced AP generation in response to naturalistic stimuli. These findings support the idea that intrinsic sensory transduction mechanisms in epidermal keratinocytes can directly elicit AP firing in nociceptive as well as tactile sensory afferents and suggest a significantly expanded role for the epidermis in sensory processing.DOI: http://dx.doi.org/10.7554/eLife.09674.001

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The relation between neonatal cry features elicited by painful circumcision procedures and the perceived urgency of those cries was investigated. Vocalizations were recorded during circumcision of 30 normal newborn males, analyzed by spectrographic methods and validated with computer techniques. The most invasive procedures elicited significantly longer crying bouts; shorter quiet intervals; shorter, more frequent vocalizations; higher peak fundamental frequencies; fewer harmonics; and greater variability of the fundamental. Cries elicited by the most intrusive procedures were judged by adult listeners to be the most urgent, and cries from similarly invasive procedures were judged to be of the same degree of urgency. Cries appeared to be judged along 3 dimensions described by harmonic, temporal, and pitch characteristics. Subjective judgments and objective quantitative data converge to demonstrate that infants' cries are perceived as varying and, objectively, do systematically vary with respect to the intensity of painful stimuli.

To assess the frequency of an evolution to stable moderate drinking among alcoholics coming to medical or psychiatric treatment facilities, we examined the five- to seven-year outcome for 1289 diagnosed alcoholics treated in our facilities during a two-year period (between 1973 and 1975). We obtained data from personal interviews, records, or both for 83 per cent of the sample. Only 1.6 per cent of the subjects met our definition of stable moderate drinking at follow-up, 15 per cent had become totally abstinent, and 4.6 per cent were mostly abstinent with occasional drinking. The only predictors of moderate drinking that we found were female sex and less severe alcoholism. The evolution to stable moderate drinking appears to be a rare outcome among alcoholics treated at medical or psychiatric facilities.