Optogenetic Activation of Interneuron Subtypes Modulates Visual Contrast Responses of Mouse V1 Neurons.

Interneurons are critical for information processing in the cortex. In vitro optogenetic studies in mouse primary visual cortex (V1) have sketched the connectivity of a local neural circuit comprising excitatory pyramidal neurons and distinct interneuron subtypes that express parvalbumin (Pvalb+), somatostatin (SOM+), or vasoactive intestinal peptide (VIP+). However, in vivo studies focusing on V1 orientation tuning have ascribed discrepant computational roles to specific interneuron subtypes. Here, we sought to clarify the differences between interneuron subtypes by examining the effects of optogenetic activation of Pvalb+, SOM+, or VIP+ interneurons on contrast tuning of V1 neurons while also accounting for cortical depth and photostimulation intensity. We found that illumination of the cortical surface produced a similar spectrum of saturating additive photostimulation effects in all 3 interneuron subtypes, which varied with cortical depth rather than light intensity in Pvalb+ and SOM+ cells. Pyramidal cell modulation was well explained by a conductance-based model that incorporated these interneuron photostimulation effects.

Activating parvalbumin-expressing interneurons produces iceberg effects in mouse primary visual cortex neurons.

In the primary visual cortex (V1) inhibitory interneurons form a local circuit with excitatory pyramidal cells to produce distinct receptive field properties. Parvalbumin-expressing interneurons (Pvalb+) are the most common subclass of V1 interneurons, and studies of orientation tuning indicate they shape pyramidal stimulus selectivity by balancing excitation with inhibition relative to the spike threshold. The iceberg effect, where subthreshold responses have broader tuning than spiking responses, predicts that other receptive field properties besides orientation tuning should also be affected by this balance mediated by Pvalb+ cells. To test this, we measured receptive field size and visual latency of pyramidal cells while Pvalb+ activity was optogenetically increased. We found that amplifying Pvalb+ input to pyramidal cells significantly increased their latency and decreased their receptive field size, which corroborates the proposed role of Pvalb+ interneurons in sculpting pyramidal tuning by controlling cortical gain.

Using a Logic Model to Enable and Evaluate Long-Term Outcomes of a Mass Casualty Training Program: A Single Center Case Study.

PURPOSE: Global health disasters are on the rise and can occur at any time with little advance warning, necessitating preparation. The authors created a comprehensive evidence-based Emergency Preparedness Training Program focused on long-term retention and sustained learner engagement. METHOD: A prospective observational study was conducted of a simulation-based mass casualty event training program designed using an outcomes-based logic model. A total of 25 frontline healthcare workers from multiple hospital sites in the New York metropolitan area participated in an 8-hour immersive workshop. Data was collected from assessments, and surveys provided to participants 3 weeks prior to the workshop, immediately following the workshop, and 3 months after completion of the workshop. RESULTS: The mean percentage of total knowledge scores improved across pre-workshop, post-workshop and retention (3 months post-workshop) assessments (53.2% vs. 64.8% vs. 67.6%, P < 0.05). Average comfort scores in the core MCI competencies increased across pre-workshop, post-workshop and retention self-assessments (P < 0.01). Of the participants assessed at 3 months retention (n = 14, 56%), 50.0% (n = 7) assisted in updating their hospital's emergency operations plan and 50.0% (n = 7) pursued further self-directed learning in disaster preparedness medicine. CONCLUSIONS: The use of the logic model provided a transparent framework for the design, implementation, and evaluation of a competency-based EPT program at a single academic center.

Rethinking Surge Preparedness After COVID-19: Effective Patient Load Balancing Within Health Systems and Beyond.

Within weeks of New York State's first confirmed case of COVID-19, New York City became the epicenter of the nation's COVID-19 pandemic. With more than 80,000 COVID-19 hospitalizations during the first wave alone, hospitals in downstate New York were forced to adapt existing procedures to manage the surge and care for patients facing a novel disease. Given the unprecedented surge, effective patient load balancing-moving patients from a hospital with diminishing capacity to another hospital within the same health system with relatively greater capacity-became chief among the capabilities required of New York health systems. The Greater New York Hospital Association invited members of downstate New York's 6 largest health systems to talk about how each of their systems evolved their patient load balancing procedures throughout the pandemic. Informed by their insights, experiences, lessons learned, and collaboration, we collectively present a set of consensus recommendations and best practices for patient load balancing at the facility and health system level, which may inform regional approaches to patient load balancing.

Creation of a medical ward from non-clinical space amidst the Covid-19 pandemic.

INTRODUCTION: Hospitals were mandated to dramatically increase capacity during the Covid-19 crisis in New York City. Conversion of non-clinical space into medical units designated for Covid-19 patients became necessary to accommodate this mandate. METHODS: Non-clinical space was converted into medical units at multiple campuses of a large academic hospital system over 1 week. The conversion required construction to deliver basic care including oxygen supplementation. Creation of provider workspaces, handwashing areas, and colour-coded infection control zones was prioritized. Selection criteria were created with a workflow to determine appropriate patients for transfer into converted space. Staffing of converted space shifted as hospitalizations surged. RESULTS: The unit was open for 18 days and accommodated 170 unique patients. Five patients (2.9%) required transfer to a higher level of care. There were no respiratory arrests, cardiac arrests, or deaths in the new unit. CONCLUSION: Converting non-clinical space to a medical unit was accomplished quickly with staffing, workflow for appropriate patients, few patients who returned to a higher level of care, and no respiratory or cardiac arrests or deaths on the unit.