Management of High Acuity Patients in Pediatric Medical Settings: The Role of Consultation/Liaison Psychologists During the Growing Mental Health Crisis

Since the onset of the COVID-19 pandemic, consultation/liaison (C/L) psychologists had to drastically shift their practices to care for psychiatrically acute pediatric patients admitted to medical settings. The aim of the current study was to provide an updated state of the field surrounding these changes and their implications for clinical practice. Psychologists and psychology post-doctoral fellows completed an anonymous, 51-item survey distributed via a national professional organization listserv. The results review responses, by percentages, about C/L team composition and practice patterns, as they relate to suicide risk assessments, transfers to inpatient psychiatric and other levels of care, intervention for boarding patients, and disposition and safety planning. Thematically coded qualitative responses regarding impact and management of high acuity patients are also summarized. The state of the field outlined by this survey suggests an increase in C/L assessments and interventions delivered to pediatric patients with acute psychiatric needs, as well as a reverberating effects on provider wellness. Ensuring providers establish competency for this subset of patients is vital to the continued provision of optimal patient care and to sustained provider wellness. Considerations for the field are explored.

Evolution of compound eye morphology underlies differences in vision between closely related Drosophila species

BACKGROUND

Insects have evolved complex visual systems and display an astonishing range of adaptations for diverse ecological niches. Species of Drosophila melanogaster subgroup exhibit extensive intra- and interspecific differences in compound eye size. These differences provide an excellent opportunity to better understand variation in insect eye structure and the impact on vision. Here we further explored the difference in eye size between D. mauritiana and its sibling species D. simulans.

RESULTS

We confirmed that D. mauritiana have rapidly evolved larger eyes as a result of more and wider ommatidia than D. simulans since they recently diverged approximately 240,000 years ago. The functional impact of eye size, and specifically ommatidia size, is often only estimated based on the rigid surface morphology of the compound eye. Therefore, we used 3D synchrotron radiation tomography to measure optical parameters in 3D, predict optical capacity, and compare the modelled vision to in vivo optomotor responses. Our optical models predicted higher contrast sensitivity for D. mauritiana, which we verified by presenting sinusoidal gratings to tethered flies in a flight arena. Similarly, we confirmed the higher spatial acuity predicted for Drosophila simulans with smaller ommatidia and found evidence for higher temporal resolution.

CONCLUSIONS

Our study demonstrates that even subtle differences in ommatidia size between closely related Drosophila species can impact the vision of these insects. Therefore, further comparative studies of intra- and interspecific variation in eye morphology and the consequences for vision among other Drosophila species, other dipterans and other insects are needed to better understand compound eye structure-function and how the diversification of eye size, shape, and function has helped insects to adapt to the vast range of ecological niches.

Identifying the severity of diabetic retinopathy by visual function measures using both traditional statistical methods and interpretable machine learning: a cross-sectional study

AIMS/HYPOTHESIS

To determine the extent to which diabetic retinopathy severity stage may be classified using machine learning (ML) and commonly used clinical measures of visual function together with age and sex.

METHODS

We measured the visual function of 1901 eyes from 1032 participants in the Northern Ireland Sensory Ageing Study, deriving 12 variables from nine visual function tests. Missing values were imputed using chained equations. Participants were divided into four groups using clinical measures and grading of ophthalmic images: no diabetes mellitus (no DM), diabetes but no diabetic retinopathy (DM no DR), diabetic retinopathy without diabetic macular oedema (DR no DMO) and diabetic retinopathy with DMO (DR with DMO). Ensemble ML models were fitted to classify group membership for three tasks, distinguishing (A) the DM no DR group from the no DM group; (B) the DR no DMO group from the DM no DR group; and (C) the DR with DMO group from the DR no DMO group. More conventional multiple logistic regression models were also fitted for comparison. An interpretable ML technique was used to rank the contribution of visual function variables to predictions and to disentangle associations between diabetic eye disease and visual function from artefacts of the data collection process.

RESULTS

The performance of the ensemble ML models was good across all three classification tasks, with accuracies of 0.92, 1.00 and 0.84, respectively, for tasks A-C, substantially exceeding the accuracies for logistic regression (0.84, 0.61 and 0.80, respectively). Reading index was highly ranked for tasks A and B, whereas near visual acuity and Moorfields chart acuity were important for task C. Microperimetry variables ranked highly for all three tasks, but this was partly due to a data artefact (a large proportion of missing values).

CONCLUSIONS/INTERPRETATION

Ensemble ML models predicted status of diabetic eye disease with high accuracy using just age, sex and measures of visual function. Interpretable ML methods enabled us to identify profiles of visual function associated with different stages of diabetic eye disease, and to disentangle associations from artefacts of the data collection process. Together, these two techniques have great potential for developing prediction models using untidy real-world clinical data.

The Presidential Symposium at the International Congress of Neuroethology 2022 in Lisbon, Portugal

In this special issue of articles from leading neuroethologists-all of whom gave outstanding presentations within the Presidential Symposium of the 2022 International Congress of Neuroethology held in Lisbon, Portugal-we learn about the role of cryptochrome molecules in the magnetic sense of animals, how honeybees construct their honeycombs, why fish eyes are built the way they are in species from different depths, how archerfish intercept their newly downed prey with a swift muscular curving of the body (known as a C-start) and how birds process optic flow information to control flight. Each contribution showcases how nervous systems have evolved to control behaviour, the raison d'être of neuroethology.

Automated APACHE II and SOFA score calculation using real-world electronic medical record data in a single center

The integration of illness severity and organ dysfunction scores into clinical practice, including the APACHE II and SOFA scores, has been challenging due to constraints associated to manual score calculation. With electronic medical records (EMR), score calculation automation using data extraction scripts has emerged as a solution. We aimed to demonstrate that APACHE II and SOFA scores calculated with an automated EMR-based data extraction script predict important clinical endpoints. In this retrospective cohort study, every adult patient admitted to one of our three ICUs, between July 1, 2019, and December 31, 2020, were enrolled. For every patient, an automated ICU admission APACHE II score was calculated using EMR data and minimal clinician input. Fully automated daily SOFA scores were calculated for every patient. 4 794 ICU admissions met our selection criteria. Of these ICU admissions, 522 deaths were recorded (10.9% in-hospital mortality rate). The automated APACHE II was discriminant for in-hospital mortality (AU-ROC = 0.83 (95% CI 0.81-0.85)). We observed an association between the APACHE II score and ICU LOS, with a statistically significant mean increase of 1.1 days of ICU LOS (1.1 [1-1.2]; p =  < .0001) for each 10 units increase in APACHE score. SOFA score curves did not discrimate significantly between survivors and non-survivors. A partially automated APACHE II score, calculated with real-world EMR data using an extraction script, is associated with in-hospital mortality risk. The automated APACHE II score could potentially constitute an acceptable surrogate of ICU acuity to be used in resource allocation and triaging, especially in time of high demand for ICU beds.

Neurosurgery Subspecialty Practice During a Pandemic: A Multicenter Analysis of Operative Practice in 7 U.S. Neurosurgery Departments During Coronavirus Disease 2019

OBJECTIVE

Changes to neurosurgical practices during the coronavirus disease 2019 (COVID-19) pandemic have not been thoroughly analyzed. We report the effects of operative restrictions imposed under variable local COVID-19 infection rates and health care policies using a retrospective multicenter cohort study and highlight shifts in operative volumes and subspecialty practice.

METHODS

Seven academic neurosurgery departments' neurosurgical case logs were collected; procedures in April 2020 (COVID-19 surge) and April 2019 (historical control) were analyzed overall and by 6 subspecialties. Patient acuity, surgical scheduling policies, and local surge levels were assessed.

RESULTS

Operative volume during the COVID-19 surge decreased 58.5% from the previous year (602 vs. 1449, P = 0.001). COVID-19 infection rates within departments' counties correlated with decreased operative volume (r = 0.695, P = 0.04) and increased patient categorical acuity (P = 0.001). Spine procedure volume decreased by 63.9% (220 vs. 609, P = 0.002), for a significantly smaller proportion of overall practice during the COVID-19 surge (36.5%) versus the control period (42.0%) (P = 0.02). Vascular volume decreased by 39.5% (72 vs. 119, P = 0.01) but increased as a percentage of caseload (8.2% in 2019 vs. 12.0% in 2020, P = 0.04). Neuro-oncology procedure volume decreased by 45.5% (174 vs. 318, P = 0.04) but maintained a consistent proportion of all neurosurgeries (28.9% in 2020 vs. 21.9% in 2019, P = 0.09). Functional neurosurgery volume, which declined by 81.4% (41 vs. 220, P = 0.008), represented only 6.8% of cases during the pandemic versus 15.2% in 2019 (P = 0.02).

CONCLUSIONS

Operative restrictions during the COVID-19 surge led to distinct shifts in neurosurgical practice, and local infective burden played a significant role in operative volume and patient acuity.

The Safety INdEx of Prehospital On Scene Triage (SINEPOST) study: the development and validation of a risk prediction model to support ambulance clinical transport decisions on-scene-a protocol

BACKGROUND

Demand for both the ambulance service and the emergency department (ED) is rising every year and when this demand is excessive in both systems, ambulance crews queue at the ED waiting to hand patients over. Some transported ambulance patients are 'low-acuity' and do not require the treatment of the ED. However, paramedics can find it challenging to identify these patients accurately. Decision support tools have been developed using expert opinion to help identify these low acuity patients but have failed to show a benefit beyond regular decision-making. Predictive algorithms may be able to build accurate models, which can be used in the field to support the decision not to take a low-acuity patient to an ED.

METHODS AND ANALYSIS

All patients in Yorkshire who were transported to the ED by ambulance between July 2019 and February 2020 will be included. Ambulance electronic patient care record (ePCR) clinical data will be used as candidate predictors for the model. These will then be linked to the corresponding ED record, which holds the outcome of a 'non-urgent attendance'. The estimated sample size is 52,958, with 4767 events and an EPP of 7.48. An XGBoost algorithm will be used for model development. Initially, a model will be derived using all the data and the apparent performance will be assessed. Then internal-external validation will use non-random nested cross-validation (CV) with test sets held out for each ED (spatial validation). After all models are created, a random-effects meta-analysis will be undertaken. This will pool performance measures such as goodness of fit, discrimination and calibration. It will also generate a prediction interval and measure heterogeneity between clusters. The performance of the full model will be updated with the pooled results.

DISCUSSION

Creating a risk prediction model in this area will lead to further development of a clinical decision support tool that ensures every ambulance patient can get to the right place of care, first time. If this study is successful, it could help paramedics evaluate the benefit of transporting a patient to the ED before they leave the scene. It could also reduce congestion in the urgent and emergency care system.

TRIAL REGISTRATION

This study was retrospectively registered with the ISRCTN: 12121281.

Pediatric emergency department utilization during the COVID-19 pandemic in New York City

Objectives

This study describes the utilization of a pediatric emergency department (ED) during the early months of the COVID-19 pandemic in the initial U.S. epicenter, including the impact on visit acuity and incidences of common diagnoses.

Study Design

We performed an observational retrospective review of patients younger than 18 years old seen in a New York City pediatric ED from March 7th to May 6th 2020, and during the same time period in 2018 and 2019. Demographics, visit details, diagnoses, and dispositions were compared. Validated algorithms were utilized to create practical diagnosis groupings and to determine the probability of a visit requiring emergent evaluation.

Results

ED visits during the pandemic decreased by 56% to an average daily census of 67 patients, from an anticipated 152. Admission rates rose from 13.3% to 17.4% (p<0.001), and the proportion of triage Emergency Severity Index level 1 and 2 patients increased by 23.7% (p<0.001). Non-emergent visits dropped from 32.3% to 27.5% (p<0.001). Several common, often low-acuity diagnoses saw disproportionate reductions in visits including headache, chest pain, and minor injuries. Concerningly, visits for suicidal ideation, suicide attempt, or self-harm increased by 100% (p<0.001) and visits for evaluating abuse or neglect decreased by 89% (p=0.01).

Conclusions

Pediatric ED utilization substantially deceased during the early months of the COVID-19 pandemic in New York City, but left relatively higher patient acuity. Healthcare systems in early epicenters must also prepare for the disproportionate impact a pandemic has on the most vulnerable pediatric patients, particularly those at risk for self-harm or abuse.

Normative Reference Value for Tactile Localization Acuity among School-going Children: A Normative Research

Background and Aim:

Tactile localization (TL) is one of the standard assessments to be performed under combined cortical sensory assessment. TL is the ability to locate the point of sensory contact and surprisingly, till date there is no normal reference available for estimating TL. Hence, there is a need to calculate the normative reference of TL among school-going children aged between 8 and 13 years.

Materials and Methods:

A total of 365 healthy school-going children aged between 8 and 13 years were included in this cross-sectional observational study. Children with any neurological condition and other conditions, which prevent them from taking part in the study were excluded. The sample was recruited by stratified random sampling method from the recognized schools in Ambala district, Haryana, India. After the anthropometric measurements, TL acuity was established by point-to-point tactile localization (PPTL) technique. In this technique, the children were asked to relocate the point of contact made by the investigator over identified 15 areas, and after that the distance between the point of contact made by the principal investigator and the relocation point made by the children is measured in centimeters (cm). The mean of three readings were used to estimate TL acuity.

Result:

TL acuity ranges from 0.9 (0.5, 1.5) cm in little finger of palm to 1.5 (1.0, 2.5) cm in middle of posterior arm. TL acuity increases with increasing age. There exist no significant (P ≥ 0.05) difference in the normative reference value between male and female among the identified 15 areas.

Conclusion:

Normative reference values of TL acuity have been established among school-going children between 8 and 13 years.

The illness severity of patients reviewed by the medical emergency team: A scoping review

BACKGROUND

Medical emergency teams (METs) are internationally used to manage hospitalised deteriorating patients. Although triggers for MET review and hospital outcomes have previously been widely reported, the illness severity at the point of MET review has not been reported. As such, levels of clinical acuity and patient dependency representing the risk of exposure to short-term adverse clinical outcomes remain largely unknown.

OBJECTIVE

This scoping review sought to understand the illness severity of MET review recipients in terms of acuity and dependency.

METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews. The published and grey literature since 2009 was searched to identify relevant articles reporting illness severity scores associated with hospitalised adult inpatients reviewed by a MET. After applying the inclusion and exclusion criteria, 17 articles (16 quantitative studies, one mixed-methods study) were reviewed, summarised, collated, and reported.

RESULTS

A total of 17 studies reported clinical acuity metrics for patients reviewed by a MET. No studies described an integrated risk score encompassing acuity, patient dependency, or wider parameters that might be associated with increased patient risk or the need for intervention. Multi-MET review, the use of specialist interventions, and delayed/transfer to the intensive care unit were associated with a greater risk of clinical deterioration, higher clinical acuity score, and predicted mortality risk. A single dependency metric was not reported although organisational levels of care, the duration of MET review, MET interventions, chronic illness, and frailty were inferred proxy measures.

CONCLUSION

Of the 17 studies reviewed, no single study provided an integrated assessment of illness severity from which to stratify risk or support patient management processes. Patients reviewed by a MET have variable and rapidly changing health needs that make them particularly vulnerable. The lack of high-quality data reporting acuity and dependency limits our understanding of true clinical risk and subsequent opportunities for pathway development.

Improving ED Emergency Severity Index Acuity Assignment Using Machine Learning and Clinical Natural Language Processing

INTRODUCTION

Triage is critical to mitigating the effect of increased volume by determining patient acuity, need for resources, and establishing acuity-based patient prioritization. The purpose of this retrospective study was to determine whether historical EHR data can be used with clinical natural language processing and machine learning algorithms (KATE) to produce accurate ESI predictive models.

METHODS

The KATE triage model was developed using 166,175 patient encounters from two participating hospitals. The model was tested against a random sample of encounters that were correctly assigned an acuity by study clinicians using the Emergency Severity Index (ESI) standard as a guide.

RESULTS

At the study sites, KATE predicted accurate ESI acuity assignments 75.7% of the time compared with nurses (59.8%) and the average of individual study clinicians (75.3%). KATE's accuracy was 26.9% higher than the average nurse accuracy (P <.001). On the boundary between ESI 2 and ESI 3 acuity assignments, which relates to the risk of decompensation, KATE's accuracy was 93.2% higher, with 80% accuracy compared with triage nurses 41.4% accuracy (P <.001).

DISCUSSION

KATE provides a triage acuity assignment more accurate than the triage nurses in this study sample. KATE operates independently of contextual factors, unaffected by the external pressures that can cause under triage and may mitigate biases that can negatively affect triage accuracy. Future research should focus on the impact of KATE providing feedback to triage nurses in real time, on mortality and morbidity, ED throughput, resource optimization, and nursing outcomes.

Oncology Nursing Considerations when Developing Outpatient Staffing and Acuity Models

OBJECTIVES

Objectives include review of existing benchmarks and nurse-sensitive indicators relevant to the ambulatory care setting. Applying the data to existing ambulatory staffing models with consideration of multiple clinic settings that include medical oncology, infusion, and stem cell transplant clinics. And to describe key considerations needed to optimize oncology care efficiently with an acuity-based staffing model.

DATA SOURCES

Published literature indexed in PubMed, CINAHL, textbooks.

CONCLUSION

In today's complex oncology environment, optimization and utilization of outpatient facilities is essential in providing high-quality care and improving satisfaction of patients as well as providers and staff.

IMPLICATIONS FOR NURSING PRACTICE

Nurse leaders should utilize benchmarking data to ensure staffing levels are appropriate, given the size and scope of their facility. Staff nurses should be engaged to ensure that acuity tools are developed in accordance with their experiences and perceptions of patient care.

Comparison of contrast sensitivity in macaque monkeys and humans

Contrast sensitivity functions reveal information about a subject's overall visual ability and have been investigated in several species of nonhuman primates (NHPs) with experimentally induced amblyopia and glaucoma. However, there are no published studies comparing contrast sensitivity functions across these species of normal NHPs. The purpose of this investigation was to compare contrast sensitivity across these primates to determine whether they are similar. Ten normal humans and eight normal NHPs (Macaca fascicularis) took part in this project. Previously published data from Macaca mulatta and Macaca nemestrina were also compared. Threshold was operationally defined as two misses in a row for a descending method of limits. A similar paradigm was used for the humans except that the descending method of limits was combined with a spatial, two-alternative forced choice (2-AFC) technique. The contrast sensitivity functions were fit with a double exponential function. The averaged peak contrast sensitivity, peak spatial frequency, acuity, and area under the curve for the humans were 268.9, 3.40 cpd, 27.3 cpd, and 2345.4 and for the Macaca fascicularis were 99.2, 3.93 cpd, 26.1 cpd, and 980.9. A two-sample t-test indicated that the peak contrast sensitivities (P = 0.001) and areas under the curve (P = 0.010) were significantly different. The peak spatial frequencies (P = 0.150) and the extrapolated visual acuities (P = 0.763) were not different. The contrast sensitivities for the Macaca fascicularis, Macaca mulatta, and Macaca nemestrina were qualitatively and quantitatively similar. The contrast sensitivity functions for the NHPs had lower peak contrast sensitivities and areas under the curve than the humans. Even though different methods have been used to measure contrast sensitivity in different species of NHP, the functions are similar. The contrast sensitivity differences and similarities between humans and NHPs need to be considered when using NHPs to study human disease.

Evaluation of Aircrew Low-Intensity Threat Laser Eye Protection

Prototype low-intensity threat laser eye protection (LIT-LEP) spectacles were evaluated for US Coast Guard (USCG) cockpits and night vision goggle compatibility. The impetus for interest in aviation LIT-LEP is driven in part by the fact that easily accessible 0.5-2.0 W high-power laser pointers exceed safety standards for direct on-axis viewing. A repeated-measures experimental design was used to assess LIT-LEP performance relative to a no-LEP control for the following tasks: Near- and far contrast acuity, night vision goggle far-contrast acuity, emissive and non-emissive light source color-vision screening, and USCG multifunctional display color symbol discrimination reaction time and accuracy. Near- and far-contrast acuity results demonstrated good LIT-LEP performance for typical in- and out-of-cockpit lighting conditions. Night vision goggle performance suffered marginally at only one contrast level (85%; 20/30 acuity line). Color vision test results showed good color balance in that S-, M-, and L-cone performance did not demonstrate a clinical diagnostic color defect for emissive or non-emissive light sources when wearing LIT-LEP. Color symbol discrimination reaction-time-task results based on inverse efficiency scores revealed that some non-primary flight display colors exhibited a combination of slower speed and decreased accuracy. The findings will contribute to an acquisition decision as well as guide future LEP designs.

Emotions can alter kinesthetic acuity

Kinesthesia, the perception of our own body movements, relies on the integration of proprioceptive information arising mostly from muscle spindles, which are sensory receptors in skeletal muscles. We recently showed that emotions alter the proprioceptive messages from such muscle afferents, making them more sensitive to muscle lengthening when participants were listening sad music. Presently, we investigated whether these changes in proprioceptive feedback relating to emotional state may affect the perception of limb movements. Kinesthetic acuity was tested in 20 healthy, young adults by imposing ramp-and-hold movements that consisted of either plantar flexion or dorsiflexion movements of the ankle at 0.04°/s, or no movement. These were imposed during four emotional conditions (listening to neutral, sad, or happy music, or no music). The participants were asked to relax and focus on music (or nothing), and then they shifted their focus to the direction of an incoming movement. Once this had finished, they were asked its direction. Muscle activity, heart rate, and electrodermal activity were recorded during each trial, and after each music condition the participants rated the emotion felt on a visual analog scale. The rating of the emotional content of the music corroborated with changes in physiological measures. Kinesthetic acuity was also affected by the emotional state and found to be larger during the sad condition, as compared to the no music or neutral conditions. We conclude that emotion can shape our perception of movements, which we show here where feeling sadness significantly increase our kinesthetic acuity, this may be functionally relevant for the preparation of appropriate behavioral responses.

Cumulative inhibition in neural networks

We show how a multi-resolution network can model the development of acuity and coarse-to-fine processing in the mammalian visual cortex. The network adapts to input statistics in an unsupervised manner, and learns a coarse-to-fine representation by using cumulative inhibition of nodes within a network layer. We show that a system of such layers can represent input by hierarchically composing larger parts from smaller components. It can also model aspects of top-down processes, such as image regeneration.

Small fruit flies sacrifice temporal acuity to maintain contrast sensitivity

Holometabolous insects, like fruit flies, grow primarily during larval development. Scarce larval feeding is common in nature and generates smaller adults. Despite the importance of vision to flies, eye size scales proportionately with body size, and smaller eyes confer poorer vision due to smaller optics. Variable larval feeding, therefore, causes within-species differences in visual processing, which have gone largely unnoticed due to ad libitum feeding in the lab that results in generally large adults. Do smaller eyes have smaller ommatidial lenses, reducing sensitivity, or broader inter-ommatidial angles, reducing acuity? And to what extent might neural processes adapt to these optical challenges with temporal and spatial summation? To understand this in the fruit fly, we generated a distribution of body lengths (1.67-2.34 mm; n = 24) and eye lengths (0.33-0.44 mm; n = 24), resembling the distribution of wild-caught flies, by removing larvae from food during their third instar. We find smaller eyes (0.19 vs.0.07 mm²) have substantially fewer (978 vs. 540, n = 45) and smaller ommatidia (222 vs. 121 μm²;n = 45) separated by slightly wider inter-ommatidial angles (4.5 vs.5.5°; n = 34). This corresponds to a greater loss in contrast sensitivity (<50%) than spatial acuity (<20%). Using a flight arena and psychophysics paradigm, we find that smaller flies lose little spatial acuity (0.126 vs. 0.118CPD; n = 45), and recover contrast sensitivity (2.22 for both; n = 65) by sacrificing temporal acuity (26.3 vs. 10.8Hz; n = 112) at the neural level. Therefore, smaller flies sacrifice contrast sensitivity to maintain spatial acuity optically, but recover contrast sensitivity, almost completely, by sacrificing temporal acuity neurally.

[18F]-Fluorodeoxyglucose PET/CT imaging as a marker of carotid plaque inflammation: Comparison to immunohistology and relationship to acuity of events

BACKGROUND

[18F]-fluorodeoxyglucose (¹⁸FDG) uptake imaged with positron emission tomography (PET) and computed tomography (CT) may serve as a biomarker of plaque inflammation. This study evaluated the relationship between carotid plaque ¹⁸FDG uptake and a) intraplaque expression of macrophage and macrophage-like cellular CD68 immunohistology; b) intraplaque inflammatory burden using leukocyte-sensitive CD45 immunohistology; c) symptomatic patient presentation; d) time from last cerebrovascular event.

METHODS

54 patients scheduled for carotid endarterectomy underwent ¹⁸FDG PET/CT imaging. Maximum 18FDG uptake (SUV_max) and tissue-to-blood ratio (TBR_max) was measured for carotid plaques. Quantitative immunohistological analysis of macrophage-like cell expression (CD68) and leukocyte content (CD45) was performed.

RESULTS

¹⁸FDG uptake was related to CD68 macrophage expression (TBR_max: r = 0.51, p < 0.001), and total-plaque leukocyte CD45 expression (TBR_max: r = 0.632, p = 0.009, p < 0.001). ¹⁸FDG TBR_max uptake in carotid plaque associated with patient symptoms was greater than asymptomatic plaque (3.58 ± 1.01 vs. 3.13 ± 1.10, p = 0.008). ¹⁸FDG uptake differed between an acuity threshold of <90 days and >90 days (SUV_max:3.15 ± 0.87 vs. 2.52 ± 0.45, p = 0.015).

CONCLUSIONS

In this CAIN cohort, ¹⁸FDG uptake imaged with PET/CT serves a surrogate marker of intraplaque inflammatory macrophage, macrophage-like cell and leukocyte burden. 18FDG uptake is greater in plaque associated with patient symptoms and those with recent cerebrovascular events. Future studies are needed to relate ¹⁸FDG uptake and disease progression.

Numerical distance effect size is a poor metric of approximate number system acuity

Individual differences in the ability to compare and evaluate nonsymbolic numerical magnitudes-approximate number system (ANS) acuity-are emerging as an important predictor in many research areas. Unfortunately, recent empirical studies have called into question whether a historically common ANS-acuity metric-the size of the numerical distance effect (NDE size)-is an effective measure of ANS acuity. NDE size has been shown to frequently yield divergent results from other ANS-acuity metrics. Given these concerns and the measure's past popularity, it behooves us to question whether the use of NDE size as an ANS-acuity metric is theoretically supported. This study seeks to address this gap in the literature by using modeling to test the basic assumption underpinning use of NDE size as an ANS-acuity metric: that larger NDE size indicates poorer ANS acuity. This assumption did not hold up under test. Results demonstrate that the theoretically ideal relationship between NDE size and ANS acuity is not linear, but rather resembles an inverted J-shaped distribution, with the inflection points varying based on precise NDE task methodology. Thus, depending on specific methodology and the distribution of ANS acuity in the tested population, positive, negative, or null correlations between NDE size and ANS acuity could be predicted. Moreover, peak NDE sizes would be found for near-average ANS acuities on common NDE tasks. This indicates that NDE size has limited and inconsistent utility as an ANS-acuity metric. Past results should be interpreted on a case-by-case basis, considering both specifics of the NDE task and expected ANS acuity of the sampled population.

Measuring Olfactory Processes in Mus musculus

This paper briefly reviews the literature that describes olfactory acuity and odour discrimination learning. The results of current studies that examined the role of the neurotransmitters noradrenalin and acetylcholine in odour discrimination learning are discussed as are those that investigated pattern recognition and models of human disease. The methodology associated with such work is also described and its role in creating disparate results assessed. Recommendations for increasing the reliability and validity of experiments so as to further our understanding of olfactory processes in both healthy mice and those modelling human disease are made throughout the paper.

Visual sensitivity and spatial resolution of the planktivorous fish, Atherinomorus forskalii (Atherinidae; Rüppell, 1838), to a polarized grating

Polarized light detection has been documented in only a small number of fish species. The benefit of polarization vision for fish is not fully understood, nor is the transduction mechanism that underlies it. Past studies proposed that one possible advantage of polarization vision is that it enhances the contrast of zooplankton targets by breaking their transparency. Here, we used an optomotor apparatus to test the responses of the planktivorous Hardyhead silverside fish Atherinomorus forskalii (Atherinidae) to vertical unpolarized (intensity) and polarized gratings. We also tested and compared the spatial and temporal resolutions of A. forskalii in the intensity and polarization domains. A. forskalii responded to the polarization pattern, but only under illumination that included ultraviolet-blue (λ>380nm) wavelengths. The spatial resolution of A. forskalii was measured as a minimum separable angle of 0.57° (a 1-mm prey viewed from 100-mm distance). The temporal resolution to unpolarized vs. polarized gratings was constant, at 33 and 10Hz respectively at most of the stripe widths tested. At the smallest stripe width tested (1mm=the minimal separable angle), which correlates with the size of prey typically consumed by these fish, the temporal resolution to the polarized grating increased to 42Hz. We conclude that A. forskalii is polarization sensitive, may use polarization vision to improve detection of its planktonic prey, and that polarization may be perceived by the fish via a separate visual pathway than intensity.

Performance, usability and comparison of two versions of a new macular vision test: the handheld Radial Shape Discrimination test

Background

Central vision, critical for everyday tasks such as reading and driving, is impacted by age-related changes in the eye and by diseases such as age-related macular degeneration. The detection of changes in macular function is therefore important. The Radial Shape Discrimination (RSD) test measures the threshold at which distortions in a radial frequency pattern can be detected and there is evidence that it is more sensitive to macular pathology than visual acuity (VA). It also provides a more quantitative measure of macular function than the commonly available Amsler grid. Recently, handheld versions of the test (hRSD) in which stimuli are presented on mobile devices (e.g., Apple iPod Touch, iPhone) have been developed. We investigated the characteristics of the hRSD test in healthy participants.

Methods

Data were collected using both three-alternative forced choice (3AFC) and 4AFC versions of the hRSD test, presented on an Apple iPod Touch. For the 3AFC version, data from a single test session were available for 186 (72 male; mean ± SD age 42 ± 17y; range 16–90y) healthy participants. Test-retest data were available for subgroups of participants (intra-session: N = 74; tests approximately 2 months apart: N = 30; tests 39 months apart: N = 15). The 3AFC and 4AFC versions were directly compared in 106 participants who also completed a usability questionnaire. Distance and near VA and Pelli Robson Contrast Sensitivity (CS) data were collected and undilated fundoscopy performed on the majority of participants.

Results

Mean (±SD) 3AFC hRSD threshold was −0.77 ± 0.14 logMAR, and was statistically significantly correlated with age (Pearson r = 0.35; p < 0.001). The linear regression of hRSD threshold on age had a slope of +0.0026 compared to +0.0051 for near VA (which also correlated with age: r = 0.51; p < 0.001). There were no statistically significant differences in hRSD thresholds for any of the test-retest subgroups. We also observed no statistically significant difference between 3AFC (−0.82 ± 0.11 logMAR) and 4AFC (−0.80 ± 0.12 logMAR) hRSD thresholds (t = 1.85, p = 0.067) and participants reported excellent test usability with no strong preference expressed between the 3AFC and 4AFC versions of the test.

Discussion

The 3AFC hRSD thresholds we report are consistent with a number of previous studies, as is its greater stability in ageing compared to VA. We have also shown that in the absence of pathology, thresholds are stable over short and long timescales. The 4AFC thresholds we have reported provide a baseline for future investigations, and we have confirmed that 3AFC and 4AFC thresholds are similar, providing a basis of comparisons between studies using the different versions. As the hRSD test is easy to use and relatively inexpensive, clinical studies are now required to establish its ability to detect and monitor macular pathologies.

Visual resolution and contrast sensitivity in two benthic sharks

Sharks have long been described as having 'poor' vision. They are cone monochromats and anatomical estimates suggest they have low spatial resolution. However, there are no direct behavioural measurements of spatial resolution or contrast sensitivity. This study estimates contrast sensitivity and spatial resolution of two species of benthic sharks, the Port Jackson shark, Heterodontus portusjacksoni, and the brown-banded bamboo shark, Chiloscyllium punctatum, by recording eye movements in response to optokinetic stimuli. Both species tracked moving low spatial frequency gratings with weak but consistent eye movements. Eye movements ceased at 0.38 cycles per degree, even for high contrasts, suggesting low spatial resolution. However, at lower spatial frequencies, eye movements were elicited by low contrast gratings, 1.3% and 2.9% contrast in H portusjacksoni and C. punctatum, respectively. Contrast sensitivity was higher than in other vertebrates with a similar spatial resolving power, which may reflect an adaptation to the relatively low contrast encountered in aquatic environments. Optokinetic gain was consistently low and neither species stabilised the gratings on their retina. To check whether restraining the animals affected their optokinetic responses, we also analysed eye movements in free-swimming C. punctatum We found no eye movements that could compensate for body rotations, suggesting that vision may pass through phases of stabilisation and blur during swimming. As C. punctatum is a sedentary benthic species, gaze stabilisation during swimming may not be essential. Our results suggest that vision in sharks is not 'poor' as previously suggested, but optimised for contrast detection rather than spatial resolution.

Experience-dependent central vision deficits: Neurobiology and visual acuity

Abnormal visual experience during childhood often leads to amblyopia, with strong links to binocular dysfunction that can include poor acuity in both eyes, especially in central vision. In animal models of amblyopia, the non-deprived eye is often considered normal and what limits binocular acuity. This leaves open the question whether monocular deprivation (MD) induces binocular dysfunction similar to what is found in amblyopia. In previous studies of MD cats, we found a loss of excitatory receptors restricted to the central visual field representation in visual cortex (V1), including both eyes' columns. This led us to ask two questions about the effects of MD: how quickly are receptors lost in V1? and is there an impact on binocular acuity? We found that just a few hours of MD caused a rapid loss of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor proteins across all of V1. But after a few days of MD, there was recovery in the visual periphery, leaving a loss of AMPA receptors only in the central region of V1. We reared animals with early MD followed by a long period of binocular vision and found binocular acuity deficits that were greatest in the central visual field. Our results suggest that the greater binocular acuity deficits in the central visual field are driven in part by the long-term loss of AMPA receptors in the central region of V1.