Speed-invariant encoding of looming object distance requires power law spike rate adaptation

Neural representations of a moving object’s distance and approach speed are essential for determining appropriate orienting responses, such as those observed in the localization behaviors of the weakly electric fish, Apteronotus leptorhynchus. We demonstrate that a power law form of spike rate adaptation transforms an electroreceptor afferent’s response to “looming” object motion, effectively parsing information about distance and approach speed into distinct measures of the firing rate. Neurons with dynamics characterized by fixed time scales are shown to confound estimates of object distance and speed. Conversely, power law adaptation modifies an electroreceptor afferent’s response according to the time scales present in the stimulus, generating a rate code for looming object distance that is invariant to speed and acceleration. Consequently, estimates of both object distance and approach speed can be uniquely determined from an electroreceptor afferent’s firing rate, a multiplexed neural code operating over the extended time scales associated with behaviorally relevant stimuli.     

Effect of change in coding rules on recording diabetes in hospital administrative datasets

AimDuring 2008–2011 Australian Coding Standards mandated a causal relationship between diabetes and inpatient care as a criterion for recording diabetes as a comorbidity in hospital administrative datasets. We aim to measure the effect of the causality mandate on recorded diabetes and associated inter-hospital variations.MethodFor patients with diabetes, all admissions between 2004 and 2013 to all New South Wales acute public hospitals were investigated. Poisson mixed models were employed to derive adjusted rates and variations.ResultsThe non-recorded diabetes incidence rate was 20.7%. The causality mandate increased the incidence rate four fold during the change period, 2008–2011, compared to the pre- or post-change periods (32.5% vs 8.4% and 6.9%). The inter-hospital variation was also higher, with twice the difference in the non-recorded rate between hospitals with the highest and lowest rates (50% vs 24% and 27% risk gap). The variation decreased during the change period (29%), while the rate continued to rise (53%). Admission characteristics accounted for over 44% of the variation compared with at most two per cent attributable to patient or hospital characteristics. Contributing characteristics explained less of the variation within the change period compared to pre- or post-change (46% vs 58% and 53%). Hospital relative performance was not constant over time.ConclusionThe causality mandate substantially increased the non-recorded diabetes rate and associated inter-hospital variation. Longitudinal accumulation of clinical information at the patient level, and the development of appropriate adoption protocols to achieve comprehensive and timely implementation of coding changes are essential to supporting the integrity of hospital administrative datasets.     

Trunk,pelvis and lower limb coordination between anticipated and unanticipated sidestep cutting in females

BackgroundEmerging research has suggested a plausible relationship may exist between lower limb coordination and musculoskeletal injury. A small number of studies have investigated the link between coordination and anterior cruciate ligament (ACL) injury during sidestep cutting. While prior work has shown unanticipated sidestep cutting to exhibit a more ‘at risk’ kinematic profile compared to anticipated tasks, a detailed understanding of the coordination between multiple joints and how they differ during unanticipated actions is lacking, particularly in females.Research questionThe purpose of this study was to observe the difference in trunk, pelvis and lower limb coordination and coordination variability during a dynamic, sidestep cutting task under anticipated and unanticipated conditions in a healthy female cohort.MethodsThree-dimensional motion analysis data were recorded during anticipated and unanticipated sidestep cutting for nineteen healthy female participants (age, 24 ± 3yrs; height, 164 ± 5 cm; and weight, 58 ± 6 kg). Vector coding methodology was used to calculate coordination and coordination variability values and statistical parametric and non-parametric mapping was used to comprehensively determine differences between anticipated and unanticipated conditions.ResultsDifferences were observed between anticipated and unanticipated conditions in the hip flexion – knee abduction angle (89 % of stance), hip rotation – knee abduction angle (55 % of stance), knee flexion – knee abduction angle (81–83 %, 86 % and 88–89 %) and knee flexion – ankle flexion angle (14–18 %) coupling angles. Differences in coupling angle variability were also observed with only one cluster of significance seen in hip abduction – knee abduction variability (27–30 % of stance).SignificanceHealthy females exhibit significant differences in lower limb coupling angles and coupling angle variability between anticipated and unanticipated sidestep cutting. Interventions aimed at reducing ACL injury risk may need to consider that anticipated and unanticipated sidestep cutting tasks present unique demands, and therefore should both be trained specifically.     

From the Cover: Echolocating bats rely on an innate speed-of-sound reference

Animals must encode fundamental physical relationships in their brains. A heron plunging its head underwater to skewer a fish must correct for light refraction, an archerfish shooting down an insect must “consider” gravity, and an echolocating bat that is attacking prey must account for the speed of sound in order to assess its distance. Do animals learn these relations or are they encoded innately and can they adjust them as adults are all open questions. We addressed this question by shifting the speed of sound and assessing the sensory behavior of a bat species that naturally experiences different speeds of sound. We found that both newborn pups and adults are unable to adjust to this shift, suggesting that the speed of sound is innately encoded in the bat brain. Moreover, our results suggest that bats encode the world in terms of time and do not translate time into distance. Our results shed light on the evolution of innate and flexible sensory perception.

Every organism must reliably sense its environment in order to survive and reproduce (1). Some sensory systems are innate and unalterable (2), allowing for efficient use even by naïve newborn animals (3–5). Others require learning or experience-dependent development—usually during a critical period during ontogeny (6, 7), though sometimes retained through adulthood (8), allowing for adapting sensing to changing environments (9, 10). The ability to accurately estimate distances with sub-centimeter accuracy is a hallmark of bat echolocation (11–13). Bats achieve this accuracy by means of delay-tuned neurons—neurons that are activated by specific call–echo time delays, supposedly encoding target distance (14–19), although it should be noted that some work suggests that the tuning width of delay-tuned neurons might not allow the accuracy that bats exhibit in delay perception (20). Though delay tuning has been shown to be (at least partially) innate at the neural level (21), this has never been tested behaviorally. Namely, when a newborn bat takes off for the first time, does its brain correctly translate time delays into distance?Translating time into distance relies on a reference of the speed of sound (SOS). This physical characteristic of the environment is not as stable as it may seem. The SOS may change considerably due to various environmental factors such as humidity, altitude, and temperature (22). Bats (Chiroptera) are a specious and widely distributed order of highly mobile and long-lived animals. They therefore experience a range of SOSs (with more than 5% variation, see below) between species, among species, and even within the life of a single individual. We therefore speculated that the reference of the SOS may not be innate to allow for the environmentally dependent SOS experienced by each animal.To test this, we examined the acquisition of the SOS reference by exposing neonatal bats to an increased SOS environment from birth (Materials and Methods). We reared two groups of bats from birth to independent flight in two flight chambers: six bats in normal air (henceforth: “air pups”) and five bats in a helium-enriched air environment (Heliox), where the speed of sound was 15% higher (henceforth: “Heliox pups”). Notably, Heliox pups were never active and did not echolocate in non-Heliox environment (Materials and Methods). This 15% shift is higher than the ecological range and was chosen because it is high enough to enable us to document behavioral changes but low enough so as to allow the bats to function (that is, to fly despite the change in air density). In order to feed, the bats had to fly to a target positioned 1.3 m away from their wooden slit roost. Once the bats learned to fly to the target independently (after ca. 9 wk), we first documented their echolocation in the environment where they were brought up, and we then moved them to the other treatment for testing (Materials and Methods). Because bats adjust their echolocation parameters to the distance of the target, before and during flight (23), we used their echolocation to assess the bats’ target range estimates. If the SOS reference is learned based on experience, the bats raised in Heliox should have learned a faster reference, so that when they flew in normal air, they would have perceived the target as farther than it really was. We also ran the same experiments on adult bats to test adult plasticity.     

Telehealth Billing for Nurse Practitioners During COVID-19: Policy Updates

Telehealth is a growing valuable strategy to assist patients accessing needed care when unable to get to a health care setting for one of several reasons. During the coronavirus disease 2019 (COVID-19) pandemic of 2020, many health care practices were forced to implement telehealth services to meet patient and practice needs. In 2020, several temporary waivers, exceptions, and telehealth policy changes emerged across the nation. Many telehealth policies are state or federal specific. This report provides a general overview of essential telehealth policies and legislative updates along with resources and websites to guide and support nurse practitioners with contemporary regulations regarding telehealth billing.     

Clinical anatomy of the subserous layer: An amalgamation of gross and clinical anatomy

The 1998 edition of Terminologia Anatomica introduced some currently used clinical anatomical terms for the pelvic connective tissue or subserous layer. These innovations persuaded the present author to consider a format in which the clinical anatomical terms could be reconciled with those of gross anatomy and incorporated into a single anatomical glossary without contradiction or ambiguity. Specific studies on the subserous layer were undertaken on 79 Japanese women who had undergone surgery for uterine cervical cancer, and on 26 female cadavers that were dissected, 17 being formalin‐fixed and 9 fresh. The results were as follows: (a) the subserous layer could be segmentalized by surgical dissection in the perpendicular, horizontal and sagittal planes; (b) the segmentalized subserous layer corresponded to 12 cubes, or ligaments, of minimal dimension that enabled the pelvic organs to be extirpated; (c) each ligament had a three‐dimensional (3D) structure comprising craniocaudal, mediolateral, and dorsoventral directions vis‐á‐vis the pelvic axis; (d) these 3D‐structured ligaments were encoded morphologically in order of decreasing length; and (e) using these codes, all the surgical procedures for 19th century to present‐day radical hysterectomy could be expressed symbolically. The establishment of clinical anatomical terms, represented symbolically through coding as demonstrated in this article, could provide common ground for amalgamating clinical anatomy with gross anatomy. Consequently, terms in clinical anatomy and gross anatomy could be reconciled and compiled into a single anatomical glossary. Clin. Anat. 29:508–515, 2016. © 2015 Wiley Periodicals, Inc.     

Microanalytic coding versus global rating of maternal parenting behaviour

This study examined the relationship between microanalytic coding and global rating systems when coding maternal parenting behaviour in two contexts. Observational data from 55 mother–child interactions with two- to four-year-old children, in either a mealtime (clinic; N?=?20 or control; N?=?20) or a playtime context (community; N?=?15), were coded via both microanalytic and global systems. Results from the microanalytic coding and global rating demonstrated similar results, with both scales showing adequate psychometric properties. No difference was found in the sensitivity of the two systems in the control sample; however, the global method demonstrated more sensitivity in measuring behaviour in the playtime context. This finding may indicate that global ratings are more sensitive in a population with high base rates of positivity or in a playtime context. This study highlights the incongruence of different measurement methods and emphasises the importance of considering coding methodology for different types of populations.     

Plan responses to diagnosis-based payment: Evidence from Germany’s morbidity-based risk adjustment

Many competitive health insurance markets adjust payments to participating health plans according to their enrollees’ risk − including based on diagnostic information. We investigate responses of German health plans to the introduction of morbidity-based risk adjustment in the Statutory Health Insurance in 2009, which triggers payments based on “validated” diagnoses by providers. Using the regulator’s data from office-based physicians, we estimate a difference-in-difference analysis of the change in the share and number of validated diagnoses for ICD codes that are inside or outside the risk adjustment but are otherwise similar. We find a differential increase in the share of validated diagnoses of 2.6 and 3.6 percentage points (3–4%) between 2008 and 2013. This increase appears to originate from both a shift from not-validated toward validated diagnoses and an increase in the number of such diagnoses. Overall, our results indicate that plans were successful in influencing physicians’ coding practices in a way that could lead to higher payments.     

Activation amplitude patterns do not change for back muscles but are altered for abdominal muscles between dominant and non-dominant hands during one-handed lifts

It is assumed when lifting with the dominant hand that the relationship between contralateral and ipsilateral trunk muscle responses are similar to when lifting with the non-dominant hand. The purpose of this study was to quantify trunk muscle activation amplitude patterns during right- and left-handed lifts. Surface electromyography (EMG) and kinematic variables were recorded from 29 healthy subjects. Minimal trunk and pelvis motion was observed. Three principal patterns accounted for 95% of the variation in the EMG data indicating minimal variation in the pattern. Significant differences in scores captured different recruitment strategies for reach and hand. Selective and differential recruitment of back sites characterized lifts at greater distances from the body, whereas co-activation between internal oblique and back sites characterized lifts closer to the body. While the results showed no handedness effect for back muscles, the external oblique responded differently between right- and left-handed lifts. Specific recruitment strategies were used to account for subtle changes in reach and asymmetrical demands.