Functional role of airflow-sensing hairs on the bat wing.

The wing membrane of the big brown bat (Eptesicus fuscus) is covered by a sparse grid of microscopic hairs. We showed previously that various tactile receptors (e.g., lanceolate endings and Merkel cell neurite complexes) are associated with wing-hair follicles. Furthermore, we found that depilation of these hairs decreased the maneuverability of bats in flight. In the present study, we investigated whether somatosensory signals arising from the hairs carry information about airflow parameters. Neural responses to calibrated air puffs on the wing were recorded from primary somatosensory cortex of E. fuscus Single units showed sparse, phasic, and consistently timed spikes that were insensitive to air-puff duration and magnitude. The neurons discriminated airflow from different directions, and a majority responded with highest firing rates to reverse airflow from the trailing toward the leading edge of the dorsal wing. Reverse airflow, caused by vortices, occurs commonly in slowly flying bats. Hence, the present findings suggest that cortical neurons are specialized to monitor reverse airflow, indicating laminar airflow disruption (vorticity) that potentially destabilizes flight and leads to stall. NEW & NOTEWORTHY: Bat wings are adaptive airfoils that enable demanding flight maneuvers. The bat wing is sparsely covered with sensory hairs, and wing-hair removal results in reduced flight maneuverability. Here, we report for the first time single-neuron responses recorded from primary somatosensory cortex to airflow stimulation that varied in amplitude, duration, and direction. The neurons show high sensitivity to the directionality of airflow and might act as stall detectors.

Morphology and deflection properties of bat wing sensory hairs: scanning electron microscopy, laser scanning vibrometry, and mechanics model.

Bat wings are highly adaptive airfoils that enable demanding flight maneuvers, which are performed with astonishing robustness under turbulent conditions, and stability at slow flight velocities. The bat wing is sparsely covered with microscopically small, sensory hairs that are associated with tactile receptors. In a previous study we demonstrated that bat wing hairs are involved in sensing airflow for improved flight maneuverability. Here, we report physical measurements of these hairs and their distribution on the wing surface of the big brown bat, Eptesicus fuscus, based on scanning electron microscopy analyses. The wing hairs are strongly tapered, and are found on both the dorsal and ventral wing surfaces. Laser scanning vibrometry tests of 43 hairs from twelve locations across the wing of the big brown bat revealed that their natural frequencies inversely correlate with length and range from 3.7 to 84.5 kHz. Young's modulus of the average wing hair was calculated at 4.4 GPa, which is comparable with rat whiskers or arthropod airflow-sensing hairs.

Organization of the primary somatosensory cortex and wing representation in the Big Brown Bat, Eptesicus fuscus.

Bats are the only mammals capable of true powered flight. The bat wing exhibits specializations, allowing these animals to perform complicated flight maneuvers like landing upside-down, and hovering. The wing membrane contains various tactile receptors, including hair-associated Merkel receptors that might be involved in stabilizing bat flight. Here, we studied the neuronal representation of the wing membrane in the primary somatosensory cortex (S1) of the anesthetized Big Brown Bat, Eptesicus fuscus, using tactile stimulation with calibrated monofilaments (von Frey hairs) while recording from multi-neuron clusters. We also measured cortical response thresholds to tactile stimulation of the wings.The body surface is mapped topographically across the surface of S1, with the head, foot, and wing being overrepresented. The orientation of the wing representation is rotated compared to the hand representaion of terrestrial mammals, confirming results from other bat species. Although different wing membrane parts derive embryologically from different body parts, including the flank (plagiopatagium), the tactile sensitivity of the entire flight membrane (0.2-1.2 mN) is remarkably close or even higher (dactylopatagium) than the average tactile sensitivity of the human fingertip.

An electronic survey of physicians using online clinical discussion groups: a brief report.

INTRODUCTION: Online discussion groups are a relatively new form of informal communication among physicians. Physicians' Online, an Internet-based medical information and communication network with a current membership base that includes more than 200,000, United States physicians, contains extensive bulletin-board discussion areas with more than 47,000 topics posted to date. There are no published data available regarding the characteristics and behaviors of the individuals who participate in these discussions. METHODS: To better characterize the users of these groups, in March 1998, we posted an eight-question, multiple-choice electronic survey on Physicians' Online's home page inviting users of the clinical discussion groups to participate. RESULTS: We analyzed responses from 586 participants. The most common characteristics were: urban and Northeastern United States location, age less than 55 years, clinical practice of internal medicine or one of its subspecialties, private solo or single/multispecialty group practice, and reported weekly consultation with three or less colleagues. Most physicians were interested in specific clinical cases. Forty-one percent of the respondents chose to read discussion groups only but rarely or never initiated or responded. CONCLUSIONS: Younger age, urban setting, private practice, and infrequent consultation with colleagues were the most common characteristics found among users of Physicians' Online's online clinical discussion groups. That specific clinical cases were the most common interest speaks to the notion that discussion groups may represent an attractive resource for helping to manage clinical cases. Future research should explore in greater depth the demographics of users, specific motivations for physician use, ways to improve active participation, and the impact on clinical practice.

Observations on experimental perineal exteriorisation of the bovine urinary bladder.

A new technique for perineal exteriorisation of the urinary bladder was evolved and successfully performed in 15 buffalo calves (Bubalus bubalis). Its merits are maximum visibility of the bladder for cystorrhaphy and easy digital accessibility to the bladder neck. An indwelling urethral catheter made of polyvinyl chloride tubing with an improvised wire stilette was well tolerated for up to 20 days.