Search

Microendoscopic calcium imaging with one-photon miniature microscopes enables unprecedented readout of neural circuit dynamics during active behavior in rodents. In this study, we describe successful application of this technology in the rhesus macaque, demonstrating plug-and-play, head-mounted recordings of cellular-resolution calcium dynamics from large populations of neurons simultaneously in bilateral dorsal premotor cortices during performance of a naturalistic motor reach task. Imaging is stable over several months, allowing us to longitudinally track individual neurons and monitor their relationship to motor behavior over time. We observe neuronal calcium dynamics selective for reach direction, which we could use to decode the animal's trial-by-trial motor behavior. This work establishes head-mounted microendoscopic calcium imaging in macaques as a powerful approach for studying the neural circuit mechanisms underlying complex and clinically relevant behaviors, and it promises to greatly advance our understanding of human brain function, as well as its dysfunction in neurological disease.

INTRODUCTION: Mechanical thrombectomy (MT) is the standard of care for acute ischemic stroke for select patients with large vessel occlusion (LVO). Although racial disparities in the utilization of thrombectomy have been previously identified, disparities in the utilization of thrombectomy in a single center with a standardized patient selection protocol have not been described in the literature. METHODS: Using the American Heart Association Quality Improvement Programs Registry, we retrospectively reviewed the records of 1,143 patients with LVO between December 1, 2014, and May 31, 2021. Patient records were assessed for demographic data, stroke risk factors, process metrics, and success of thrombectomy. A Pearson's Chi-Squared and an independent two-sample t -test were used to determine the significance. Following this, a multivariate logistic regression was run to determine predictably of thrombectomy outcomes. RESULTS: Of the 1,143 LVO patients, 567 were male (49.6%), 576 were female, (50.4%), 963 were white (84.3%), and 180 were nonwhite (15.7%). Based on our Pearson's Chi-squared analysis, female patients were more like to undergo thrombectomy compared to male patients (62.4% vs. 48.9%; P < 0.001). White patients were also more likely to undergo thrombectomy compared to nonwhite patients (58.7% vs. 39.7%; P < 0.001). After the multivariate logistic regression analysis and after controlling for comorbidities, insurance status, age, time to presentation (last known well to arrival), transfer from outside hospital, and zip codes, white patients were 2.29 times more likely to receive a thrombectomy compared to nonwhite patients (odds ratio [OR], 2.29, 95% confidence interval [CI], 1.33, 3.944). Patients with Medicare insurance were 33.57 times more likely to receive a thrombectomy compared to those without medicare (OR, 33.57, 95% CI, 20.37, 55.327). In the regression model, sex did not contribute significantly to the likelihood of receiving a thrombectomy. CONCLUSIONS: White patients were more likely to undergo MT. Female patients tended to have higher rates of MT, accounting for the fact that other variables could have influenced this. These disparities may result from a multitude of other factors such as eligibility for MT, delayed presentation, and adequate diagnosis of LVO in the emergency department. This study highlights the importance of and potential causes of these disparities. Further investigation with data from multiple centers is necessary to validate these findings and identify strategies for improving utilization of thrombectomy. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Endovascular mechanical thrombectomy (EVT) has become the standard of care treatment for both intravenous tissue plasminogen activator eligible and ineligible patients presenting with an acute ischemic stroke due to a large vessel occlusion (LVO) within 24 h. Due to limited access to EVT, patients typically present to a non-EVT-capable center and are transferred to a larger, EVT-capable center. Quality improvement work has focused on improving this process to shorten the time to definitive recanalization of the affected vessel. MATERIALS AND METHODS: We retrospectively reviewed 98 consecutive patients who were transferred from an outside institution to our Comprehensive Stroke Center from July 2019 to September 2021. Thirty-nine of these patients had a diagnosed LVO at the transferring center on computed tomography angiography and were transferred directly to the angiography suite (DAT) whereas 59 patients were transferred to our Emergency Department for further imaging (EDT). Three of the patients in the DAT group did not undergo thrombectomy as there was no LVO identified on catheter angiography and were excluded from the study. RESULTS: Demographic and medical comorbidities were similar between the two groups. The DAT group had more severe strokes on presentation compared to the EDT group as measured by the National Institute of Health Stroke Severity (17.5 vs. 15, P = 0.048). Last known well (LKW) to arrival time in the angiography suite was significantly shorter in the DAT group (280 min vs. 474 min, P = 0.002). Patients in the DAT group were revascularized faster than the EDT group relative to LKW (320 min vs. 534 min, P < 0.001) while door-to-groin puncture and door-to-revascularization rates were similar. Modified Rankin score, incidence of symptomatic intracranial hemorrhage, and need for decompressive hemicraniectomy were similar between the two groups. Successful revascularization as measured by thrombolysis in cerebral infarction score occurred at a higher rate in the DAT group but was not statistical significance (97% vs. 85%, P = 0.055). DISCUSSION/CONCLUSION: DAT resulted in safe EVT compared to EDT with significant improvement in LKW to angiography suite presentation and subsequent vessel recanalization. Patients who underwent DAT experienced similar functional outcomes compared to EDT despite experiencing more severe strokes. [ABSTRACT FROM AUTHOR]

The activity and connectivity of neurons in the primate brain underlying behavior cannot yet be completely specified, but neural networks provide complete models of the connectivity and activity that performs specific tasks and provide insight into the neural computations performed by the primate brain (Fetz and Shupe 2003). Studies of neurons in the monkey cortex have shown that short-term memory of sensory events may be mediated by sustained neural activity. Short-term memory tasks have been modeled with dynamic neural networks using a single continuous variable and a gate input to create a sample-and-hold (SAH) function (Zipser 1991; Maier 2003). Networks trained to perform these short-term memory tasks develop hidden unit activity which resembles that of cortical neurons in monkeys performing memory tasks. We here extend the investigation of single-input SAH networks to networks computing SAH for two continuous-variable inputs that have varying degrees of common mode signal. Results provide insights into computational mechanisms of associative short-term memory of sensory signals with common mode components, such as visual inputs to the two eyes, auditory inputs to the ears and proprioceptive input from multiple muscle spindle afferents. We also examined the attractor states that these SAH networks eventually reach after sufficiently long delay periods and found that these were determined by the shapes of the input-output functions of the hidden units rather than network architecture.

Background: There is limited literature concerning the use of bi-vector traction to a Mayfield following posterior cervical fusion with respect to cervical alignment parameters. The objective of this study was to determine how variability of intra-operative fixation methods for posterior cervical fusion affects post-operative cervical sagittal alignment parameters., Methods: After institutional review board (IRB) approval, retrospective chart review of a total of 54 patients who underwent posterior cervical fusion from July 2017 to December 2019 was conducted. The patients were divided into two cohorts based on their intra-operative positioning, those who were affixed to a three-point fixation system, and those who were placed in bi-vector traction. Pre- and post-operative cervical alignment parameters were measured., Results: There was no difference in post-operative sagittal parameters between the two groups. Each group showed a statistically significant difference in T1-slope when comparing pre- and post-operative measurements., Conclusions: In our study we did not find that any of our techniques including bi-vector traction, static Mayfield positioning, or dynamic Mayfield positioning were very effective in adding lordosis during posterior cervical fusion surgeries. Interestingly, we also found a statistically significant increase in T1 slope and resulting trend towards increased cervical SVA.

Study Design: Unblinded single-arm prospective clinical trial., Objective: Evaluate safety and accuracy of navigation for placement of posterior cervicothoracic instrumentation., Summary of Background Data: Computer assisted stereotactic navigation for placement of spinal instrumentation has been widely studied and implemented in the thoracic and lumbar spine. However less literature exists regarding the use of computer assisted navigation for posterior cervical instrumentation, particularly with lateral mass fixation. Here we present the first prospective study of navigated cervical lateral mass screw placement for cervicothoracic fusion., Methods: Patients who met indications for posterior cervical fusion were screened, consented, and enrolled preoperatively for instrumentation with Medtronic Infinity Occipital-Cervical-Thoracic implants, with use of intraoperative O-arm and stereotactic Stealth navigation. Postoperative CTs of the instrumented levels were obtained during the same hospital admission. Primary outcome of the trial was safety. Secondary outcomes were screw accuracy assessed by Gertzbein-Robbins grade, neurologic exams, and patient reported outcomes on the PROMIS 29 questionnaire., Results: A total of 50 patients underwent surgery, and 557 screws were placed. There were no adverse events related to the use of navigation or screw malposition. Gertzbein-Robbins grade A or B placement comprised 95% of navigated screws. There was a decrease in positive Hoffmann sign rate postoperatively, and sensory and motor exams remained stable. There was improvement in patient reported pain and sleep domains., Conclusions: Navigation for cervicothoracic instrumentation is safe overall and leads to high rates of accurately placed screws. Longer term follow up could provide more insight to whether the use of this technology results in durable improvement in spinal alignment parameters and patient reported outcomes., Level of Evidence: 3., Competing Interests: Conflicts of interest: DSX receives consulting support from NuVasive, Providence Medical Technologies. AJG and VSV receive consulting and research support from Medtronic and Nuvasive. Medtronic provided funding support for this study., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Calcium imaging has great potential to be applied to online brain-machine interfaces (BMIs). As opposed to two-photon imaging settings, a one-photon microendoscopic imaging device can be chronically implanted and is subject to little motion artifacts. Traditionally, one-photon microendoscopic calcium imaging data are processed using the constrained nonnegative matrix factorization (CNMFe) algorithm, but this batched processing algorithm cannot be applied in real-time. An online analysis of calcium imaging data algorithm (or OnACIDe) has been proposed, but OnACIDe updates the neural components by repeatedly performing neuron identification frame-by-frame, which may decelerate the update speed if applying to online BMIs. For BMI applications, the ability to track a stable population of neurons in real-time has a higher priority over accurately identifying all the neurons in the field of view. By leveraging the fact that 1) microendoscopic recordings are rather stable with little motion artifacts and 2) the number of neurons identified in a short training period is sufficient for potential online BMI tasks such as cursor movements, we proposed the short-training CNMFe algorithm (stCNMFe) that skips motion correction and neuron identification processes to enable a more efficient BMI training program in a one-photon microendoscopic setting.

Objective: Incomplete circle of Willis (CoW) configuration is an important risk factor for cerebrovascular pathology, namely aneurysm formation and ischemic stroke. This study was performed to characterize CoW variation using digital subtraction angiography and to identify demographic and physiologic features that may influence the risk of having an incomplete CoW configuration., Materials and Methods: A retrospective review of 274 patients who underwent cerebral angiography by a single surgeon for any indication was conducted. Each CoW branch was graded as normal, hypoplastic, or aplastic. Univariate and multivariate regression analyses were conducted to assess the impact of age, gender, race, and certain comorbidities on CoW configuration., Results: A complete CoW was identified in 37.23% of patients. In univariate analysis, patients <40 years old were more likely to have a complete CoW (odds ratio [OR]: 4.973, 95% confidence interval [CI]: 2.610-9.476, P < 0.001) as were patients <70 years old (OR: 2.849, 95% CI: 1.131-7.194, P < 0.05). Univariate analysis on demographic factors and comorbidities revealed CoW completeness to decrease with hypertension (OR: 0.575, 95% CI: 0.347-0.951, P = 0.031) and diabetes mellitus (OR: 0.368, 95% CI: 0.180-0.754, P = 0.006). Multivariable logistic regression analysis used to assess the impact of age on CoW completeness showed age to be an independent predictor of complete CoW, with an inverse correlation between increasing age and CoW completeness (OR: 0.955, 95% CI: 0.937-0.973, P < 0.001) after controlling for potential confounders including hypertension and diabetes mellitus., Conclusions: CoW configuration shows considerable variation with age; however, further investigation is required to elucidate the full impact of other demographic and vascular risk factors on CoW anatomy., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Brain Circulation.)