No abstract

An animal's perceived sense of orientation depends upon the head direction (HD) system found in several limbic structures and depends upon an intact peripheral vestibular labyrinth. However, how the vestibular system influences the generation, maintenance, and updating of the HD signal remains poorly understood. Anatomical and lesion studies point towards three key brainstem nuclei as being potential critical components in generating the HD signal: nucleus prepositus hypoglossi (NPH), supragenual nucleus (SGN), and dorsal paragigantocellularis reticular nuclei (PGRNd). Collectively, these nuclei are situated between the vestibular nuclei and the dorsal tegmental and lateral mammillary nuclei, which are thought to serve as the origin of the HD signal. To test this hypothesis, extracellular recordings were made in these areas while rats either freely foraged in a cylindrical environment or were restrained and rotated passively. During foraging, a large subset of cells in all three nuclei exhibited activity that correlated with changes in the rat's angular head velocity (AHV). Two fundamental types of AHV cells were observed: 1) symmetrical AHV cells increased or decreased their neural firing with increases in AHV regardless of the direction of rotation; 2) asymmetrical AHV cells responded differentially to clockwise (CW) and counter-clockwise (CCW) head rotations. When rats were passively rotated, some AHV cells remained sensitive to AHV whereas others had attenuated firing. In addition, a large number of AHV cells were modulated by linear head velocity. These results indicate the types of information conveyed in the ascending vestibular pathways that are responsible for generating the HD signal.

Background Blood transfusion is a complex process at risk for error. We aimed to implement a structured handoff during this process to improve delivery verification. Methods A multidisciplinary team participated in the Quality Academy training program at an academic medical center and implemented a structured handoff of blood delivery to the operating room using Plan-Do-Study-Act cycles between October 28, 2019 and December 1, 2019. An interrupted time series analysis was performed to investigate the proportions of verified deliveries (primary outcome) and of verified deliveries among those without a handoff (secondary outcome). Delivery duration was also assessed. Results A total of 2,606 deliveries occurred from July 1, 2019 to April 19, 2020. The baseline trend for verified deliveries was unchanging (parameter coefficient -0.0004, 95% CI -0.002 to 0.001; P=0.623). Following intervention, there was an immediate level change (parameter coefficient 0.115, 95% CI 0.053 to 0.176; P=0.001) without slope change (parameter coefficient 0.002, 95% CI -0.004 to 0.007; P=0.559). For the secondary outcome, there was no immediate level change (parameter coefficient -0.039, 95% CI -0.159 to 0.081; P=0.503) nor slope change (parameter coefficient 0.002, 95% CI -0.022 to 0.025; P=0.866). The mean (SD) delivery duration during the intervention was 12.4 (2.8) minutes, and during the post-intervention period 9.6 (1.6) minutes (mean difference 2.8, 95% CI 0.9 to 4.8, P=0.008). Conclusion Using the Quality Academy framework supported implementation of a structured handoff during blood delivery to the operating room, resulting in a significant increase in verified deliveries.