Mammalian cortex has both local and cross-area connections, suggesting vital roles for both local and cross-area neural population dynamics in cortically-dependent tasks, like movement learning. Prior studies of movement learning have focused on how single-area population dynamics change during short-term adaptation. It is unclear how cross-area dynamics contribute to movement learning, particularly long-term learning and skill acquisition. Using simultaneous recordings of rodent motor (M1) and premotor (M2) cortex and computational methods, we show how cross-area activity patterns evolve during reach-to-grasp learning in rats. The emergence of reach-related modulation in cross-area activity correlates with skill acquisition, and single-trial modulation in cross-area activity predicts reaction time and reach duration. Local M2 neural activity precedes local M1 activity, supporting top-down hierarchy between the regions. M2 inactivation preferentially affects cross-area dynamics and behavior, with minimal disruption of local M1 dynamics. Together, these results indicate that cross-area population dynamics are necessary for learned motor skills.

OBJECTIVESurgical site infection (SSI) following spine surgery causes major morbidity and greatly impedes functional recovery. In the modern era of advanced operative techniques and improved perioperative care, SSI remains a problematic complication that may be reduced with institutional practices. The objectives of this study were to 1) characterize the SSI rate and microbial etiology following spine surgery for various thoracolumbar diseases, and 2) identify risk factors that were associated with SSI despite current perioperative management.METHODSAll patients treated with thoracic or lumbar spine operations on the neurosurgery service at the University of California, San Francisco from April 2012 to April 2016 were formally reviewed for SSI using the National Healthcare Safety Network (NHSN) guidelines. Preoperative risk variables included age, sex, BMI, smoking, diabetes mellitus (DM), coronary artery disease (CAD), ambulatory status, history of malignancy, use of preoperative chlorhexidine gluconate (CHG) showers, and the American Society of Anesthesiologists (ASA) classification. Operative variables included surgical pathology, resident involvement, spine level and surgical technique, instrumentation, antibiotic and steroid use, estimated blood loss (EBL), and operative time. Multivariable logistic regression was used to evaluate predictors for SSI. Odds ratios and 95% confidence intervals were reported.RESULTSIn total, 2252 consecutive patients underwent thoracolumbar spine surgery. The mean patient age was 58.6 ± 13.8 years and 49.6% were male. The mean hospital length of stay was 6.6 ± 7.4 days. Sixty percent of patients had degenerative conditions, and 51.9% underwent fusions. Sixty percent of patients utilized presurgery CHG showers. The mean operative duration was 3.7 ± 2 hours, and the mean EBL was 467 ± 829 ml. Compared to nonfusion patients, fusion patients were older (mean 60.1 ± 12.7 vs 57.1 ± 14.7 years, p < 0.001), were more likely to have an ASA classification > II (48.0% vs 36.0%, p < 0.001), and experienced longer operative times (252.3 ± 120.9 minutes vs 191.1 ± 110.2 minutes, p < 0.001). Eleven patients had deep SSI (0.49%), and the most common causative organisms were methicillin-sensitive Staphylococcus aureus and methicillin-resistant S. aureus. Patients with CAD (p = 0.003) or DM (p = 0.050), and those who were male (p = 0.006), were predictors of increased odds of SSI, and presurgery CHG showers (p = 0.001) were associated with decreased odds of SSI.CONCLUSIONSThis institutional experience over a 4-year period revealed that the overall rate of SSI by the NHSN criteria was low at 0.49% following thoracolumbar surgery. This was attributable to the implementation of presurgery optimization, and intraoperative and postoperative measures to prevent SSI across the authors’ institution. Despite prevention measures, having a history of CAD or DM, and being male, were risk factors associated with increased SSI, and presurgery CHG shower utilization decreased SSI risk in patients.

The hallmarks of diabetics are insufficient secretion of insulin and dysregulation of glucagon. It is critical to understand release mechanisms of insulin, glucagon, and other hormones from the islets of Langerhans. In spite of remarkable advancements in diabetes research and practice, robust and reproducible models that can measure pancreatic β-cell function are lacking. Here, a microphysiological analysis platform (MAP) that allows the uniform 3D spheroid formation of pancreatic β-cell islets, large-scale morphological phenotyping, and gene expression mapping of chronic glycemia and lipidemia development is reported. The MAP enables the scaffold-free formation of densely packed β-cell spheroids (i.e., multiple array of 110 bioreactors) surrounded with a perfusion flow network inspired by physiologically relevant microenvironment. The MAP permits dynamic perturbations on the β-cell spheroids and the precise controls of glycemia and lipidemia, which allow us to confirm that cellular apoptosis in the β-cell spheroid under hyperglycemia and hyperlipidemia is mostly dependent to a reactive oxygen species-induced caspase-mediated pathway. The β-cells' MAP might provide a potential new map in the pathophysiological mechanisms of β cells.