Dynamic Range Compression in the Honey Bee Auditory System toward Waggle Dance Sounds

Honey bee foragers use a “waggle dance” to inform nestmates about direction and distance to locations of attractive food. The sound and air flows generated by dancer's wing and abdominal vibrations have been implicated as important cues, but the decoding mechanisms for these dance messages are poorly understood. To understand the neural mechanisms of honey bee dance communication, we analyzed the anatomy of antenna and Johnston's organ (JO) in the pedicel of the antenna, as well as the mechanical and neural response characteristics of antenna and JO to acoustic stimuli, respectively. The honey bee JO consists of about 300–320 scolopidia connected with about 48 cuticular “knobs” around the circumference of the pedicel. Each scolopidium contains bipolar sensory neurons with both type I and II cilia. The mechanical sensitivities of the antennal flagellum are specifically high in response to low but not high intensity stimuli of 265–350 Hz frequencies. The structural characteristics of antenna but not JO neurons seem to be responsible for the non-linear responses of the flagellum in contrast to mosquito and fruit fly. The honey bee flagellum is a sensitive movement detector responding to 20 nm tip displacement, which is comparable to female mosquito. Furthermore, the JO neurons have the ability to preserve both frequency and temporal information of acoustic stimuli including the “waggle dance” sound. Intriguingly, the response of JO neurons was found to be age-dependent, demonstrating that the dance communication is only possible between aged foragers. These results suggest that the matured honey bee antennae and JO neurons are best tuned to detect 250–300 Hz sound generated during “waggle dance” from the distance in a dark hive, and that sufficient responses of the JO neurons are obtained by reducing the mechanical sensitivity of the flagellum in a near-field of dancer. This nonlinear effect brings about dynamic range compression in the honey bee auditory system

Late morbidity during childhood and adolescence in previously premature neonates after patent ductus arteriosus closure

The health status of previously premature neonates after closure of a patent ductus arteriosus (PDA) was analyzed in childhood and adolescence. Physician questionnaires were used to study 180 hospital survivors among 210 consecutive premature neonates who underwent PDA closure between 1985 and 2005. Complete follow-up data were obtained for 129 patients (72%). During a median follow-up period of 7 years (range, 2-22 years), three late deaths (2.3%) had occurred. Only 45% of the patients were considered healthy. Morbidity included developmental delay (41.1%), pulmonary illness (12.4%), neurologic impairment (14.7%), hearing impairment (3.9%), gastrointestinal disease (3.1%), and thoracic deformity (1.2%). None of the adverse variables during the neonatal period (intraventricular hemorrhage, bradycardia apnea syndrome, bronchopulmonary dysplasia, pulmonary bleeding, hyaline membrane disease, artificial respiration time [continuous positive airway pressure + intubation], or necrotizing enterocolitis) statistically predicted respective system morbidity at the follow-up evaluation. Hyaline membrane disease (odds ratio, 2.5; p = 0.026) and longer hospitalization time (odds ratio, 1.2 days per 10 hospitalization days; p = 0.032) in the newborn period were significant predictors of an unhealthy outcome at the last follow-up evaluation. Survival until childhood after closure of a hemodynamically significant PDA in premature neonates is satisfactory. However, physical and neurodevelopmental co-morbidity persist for half of the patients, perhaps as a sequela of prematurity unrelated to ductus closure