Decoding the activity of neuronal populations in macaque primary visual cortex

Visual function depends on the accuracy of signals carried by visual cortical neurons. Combining information across neurons should improve this accuracy because single neuron activity is variable. We examined the reliability of information inferred from populations of simultaneously recorded neurons in macaque primary visual cortex. We considered a decoding framework that computes the likelihood of visual stimuli from a pattern of population activity by linearly combining neuronal responses and tested this framework for orientation estimation and discrimination. We derived a simple parametric decoder assuming neuronal independence and a more sophisticated empirical decoder that learned the structure of the measured neuronal response distributions, including their correlated variability. The empirical decoder used the structure of these response distributions to perform better than its parametric variant, indicating that their structure contains critical information for sensory decoding. These results show how neuronal responses can best be used to inform perceptual decision-making

Quantitative Assessment of Children with Osteogenesis Imperfecta

Assessments of children with Osteogenesis Imperfecta (OI) are typically limited to a physical exam and observations from a clinician during a hospital visit. Often quantitative information such as bone mineral density and outcome questionnaires is obtained, but with the increasing prevalence of motion analysis and other performance type laboratories, there are many other tools available, which could be beneficial to this patient population. These laboratories can provide date supplementary to morphologic and radiographic data that is helpful in tracking changes in the patient’s functional abilities, recover from fracture, and treatment outcomes. This chapter will cover some useful evaluation methods for children with the most commonly seen types of OI and provide some examples of their test results

Upper Extremity Biomechanical Model for Evaluation of Pediatric Joint Demands during Wheelchair Mobility

Current methods for evaluating upper extremity (UE) dynamics during pediatric wheelchair use are limited. We propose a new model to characterize UE joint kinematics and kinetics during pediatric wheelchair mobility. The bilateral model is comprised of the thorax, clavicle, scapula, upper arm, forearm, and hand segments. The modeled joints include: sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist. The model is complete and is currently undergoing pilot studies for clinical application. Results may provide considerable quantitative insight into pediatric UE joint dynamics to improve wheelchair prescription, training and long term care of children with orthopaedic disabilities

Kinematic Foot Types in Youth with Equinovarus Secondary to Hemiplegia

Background Elevated kinematic variability of the foot and ankle segments exists during gait among individuals with equinovarus secondary to hemiplegic cerebral palsy (CP). Clinicians have previously addressed such variability by developing classification schemes to identify subgroups of individuals based on their kinematics. Objective To identify kinematic subgroups among youth with equinovarus secondary to CP using 3-dimensional multi-segment foot and ankle kinematics during locomotion as inputs for principal component analysis (PCA), and K-means cluster analysis. Methods In a single assessment session, multi-segment foot and ankle kinematics using the Milwaukee Foot Model (MFM) were collected in 24 children/adolescents with equinovarus and 20 typically developing children/adolescents. Results PCA was used as a data reduction technique on 40 variables. K-means cluster analysis was performed on the first six principal components (PCs) which accounted for 92% of the variance of the dataset. The PCs described the location and plane of involvement in the foot and ankle. Five distinct kinematic subgroups were identified using K-means clustering. Participants with equinovarus presented with variable involvement ranging from primary hindfoot or forefoot deviations to deformtiy that included both segments in multiple planes. Conclusion This study provides further evidence of the variability in foot characteristics associated with equinovarus secondary to hemiplegic CP. These findings would not have been detected using a single segment foot model. The identification of multiple kinematic subgroups with unique foot and ankle characteristics has the potential to improve treatment since similar patients within a subgroup are likely to benefit from the same intervention(s)

Pauci-immune glomerulonephritis in individuals with disease associated with levamisole-adulterated cocaine: a series of 4 cases.

Exposure to levamisole-adulterated cocaine can induce a distinct clinical syndrome characterized by retiform purpura and/or agranulocytosis accompanied by an unusual constellation of serologic abnormalities including antiphospholipid antibodies, lupus anticoagulants, and very high titers of antineutrophil cytoplasmic antibodies. Two recent case reports suggest that levamisole-adulterated cocaine may also lead to renal disease in the form of pauci-immune glomerulonephritis. To explore this possibility, we reviewed cases of pauci-immune glomerulonephritis between 2010 and 2012 at an inner city safety net hospital where the prevalence of levamisole in the cocaine supply is known to be high. We identified 3 female patients and 1 male patient who had biopsy-proven pauci-immune glomerulonephritis, used cocaine, and had serologic abnormalities characteristic of levamisole-induced autoimmunity. Each also had some other form of clinical disease known to be associated with levamisole, either neutropenia or cutaneous manifestations. One patient had diffuse alveolar hemorrhage. Three of the 4 patients were treated with short courses of prednisone and cyclophosphamide, 2 of whom experienced stable long-term improvement in their renal function despite ongoing cocaine use. The remaining 2 patients developed end-stage renal disease and became dialysis-dependent. This report supports emerging concern of more wide spread organ toxicity associated with the use of levamisole-adulterated cocaine