High-density transparent graphene arrays for predicting cellular calcium activity at depth from surface potential recordings.

Optically transparent neural microelectrodes have facilitated simultaneous electrophysiological recordings from the brain surface with the optical imaging and stimulation of neural activity. A remaining challenge is to scale down the electrode dimensions to the single-cell size and increase the density to record neural activity with high spatial resolution across large areas to capture nonlinear neural dynamics. Here we developed transparent graphene microelectrodes with ultrasmall openings and a large, transparent recording area without any gold extensions in the field of view with high-density microelectrode arrays up to 256 channels. We used platinum nanoparticles to overcome the quantum capacitance limit of graphene and to scale down the microelectrode diameter to 20 µm. An interlayer-doped double-layer graphene was introduced to prevent open-circuit failures. We conducted multimodal experiments, combining the recordings of cortical potentials of microelectrode arrays with two-photon calcium imaging of the mouse visual cortex. Our results revealed that visually evoked responses are spatially localized for high-frequency bands, particularly for the multiunit activity band. The multiunit activity power was found to be correlated with cellular calcium activity. Leveraging this, we employed dimensionality reduction techniques and neural networks to demonstrate that single-cell and average calcium activities can be decoded from surface potentials recorded by high-density transparent graphene arrays.

Neural population dynamics in songbird RA and HVC during learned motor-vocal behavior.

Complex, learned motor behaviors involve the coordination of large-scale neural activity across multiple brain regions, but our understanding of the population-level dynamics within different regions tied to the same behavior remains limited. Here, we investigate the neural population dynamics underlying learned vocal production in awake-singing songbirds. We use Neuropixels probes to record the simultaneous extracellular activity of populations of neurons in two regions of the vocal motor pathway. In line with observations made in non-human primates during limb-based motor tasks, we show that the population-level activity in both the premotor nucleus HVC and the motor nucleus RA is organized on low-dimensional neural manifolds upon which coordinated neural activity is well described by temporally structured trajectories during singing behavior. Both the HVC and RA latent trajectories provide relevant information to predict vocal sequence transitions between song syllables. However, the dynamics of these latent trajectories differ between regions. Our state-space models suggest a unique and continuous-over-time correspondence between the latent space of RA and vocal output, whereas the corresponding relationship for HVC exhibits a higher degree of neural variability. We then demonstrate that comparable high-fidelity reconstruction of continuous vocal outputs can be achieved from HVC and RA neural latents and spiking activity. Unlike those that use spiking activity, however, decoding models using neural latents generalize to novel sub-populations in each region, consistent with the existence of preserved manifolds that confine vocal-motor activity in HVC and RA.

Benefits and challenges of fostering research-focused communities of practice at a specialised health sciences university: An exploratory study.

Introduction: Structured undergraduate research, whether mandatory or elective, provides undergraduate students with a unique opportunity to develop their research skills. However, the majority of the students undertake individual research projects rather than working in a group. This study explores the perceived benefits and challenges of fostering research focused communities of practice at a specialised health sciences university in Riyadh, Saudi Arabia. Methods: This cross-sectional study was conducted at the College of Medicine, King Saud bin Abdulaziz University for Health Sciences (KSAU-HS) Riyadh, Saudi Arabia. The study was approved by the Ethics Committee at the King Abdullah International Medical Research Center (KAIMRC). A self-administered questionnaire was developed that assessed the perceived benefits and challenges of doing research in groups. Data were collected using a mixture of a dichotomous and a 5-point Likert scale and were analysed using Statistical Program for Social Scientists (SPSS). Results: Of the 380 medical students invited to participate in this study, 307 completed the questionnaire, with a response rate of 80.7%. The majority of the medical students (87%) agreed on the importance of teamwork in conducting medical research. Almost all medical students (96%) believed patience and tolerance were required to make the team successful. Significant differences were found between junior and senior medical students regarding their perceived benefits (P-value = 0.0001) and challenges (P-value = 0.0007). Conclusion: Although most of the students believed that doing research in groups is essential and that working within such groups enhances their research knowledge, forming these research groups was not without problems. The need for patience and tolerance to keep the group together, the issue of free-riders and the difficulties related to which research group to join were some of the challenges students encountered.

Relationship of Plasma Gremlin 1 Levels with Body Adiposity and Glycemic Control in Saudi Female Type 2 Diabetes Patients.

Objective: Gremlin 1 is a novel adipokine that plays an important role in obesity and type 2 diabetes mellitus (T2DM). In the current study, we aimed to evaluate plasma levels of Gremlin 1 in diabetic and non-diabetic Saudi adult females and its correlation with body composition, glycemic control and lipid profile. Methods: A case-control study was conducted among 41 T2DM and 31 non-diabetic adult age matched females (controls). All patients underwent body composition by bioelectrical impedance analysis, with a commercially available body analyzer. Fasting venous samples were analyzed for glycemic markers and lipids, while plasma Gremlin 1 was measured by ELISA. The results were compared between the two groups and correlated with other anthropometric and adiposity parameters. Results: Gremlin 1 levels were elevated in T2DM patients (345 ± 26 ng/mL) when compared to control subjects (272 ± 16 ng/mL, p < 0.05). Diabetic patients having poor glycemic control had significantly higher Gremlin 1 levels (382 ± 34 ng/mL) compared to patients with good glycemic control (291 ± 37 ng/mL, p < 0.05). Pearson correlation analysis revealed a positive correlation of Gremlin 1 with fat mass (r = 0.246, p = 0.012), HbA1C (r = 0.262, p = 0.008) and HOMA-IR index (r = 0.321, p = 0.001). Conclusion: Our study demonstrates an important role of Gremlin 1 in glycemic control and body adiposity in the pathophysiology of obesity and T2DM. Gremlin 1 may emerge as a promising biomarker and therapeutic target in obesity and T2DM.

Unsupervised Channel Compression Methods in Motor Prostheses Design.

The development of high performance brain machine interfaces (BMIs) requires scaling recording channel count to enable simultaneous recording from large populations of neurons. Unfortunately, proposed implantable neural interfaces have power requirements that scale linearly with channel count. To facilitate the design of interfaces with reduced power requirements, we propose and evaluate an unsupervised-learning-based compressed sensing strategy. This strategy suggests novel neural interface architectures which compress neural data by methodically combining channels of spiking activity. We develop an entropy-based compression strategy that models the population of neurons as being generated from a lower dimensional set of latent variables and aims to minimize the loss of information in the latent variables due to compression. We evaluate compressed features by inferring the latent variables from these features and measuring the accuracy with which the activity of held out neurons and arm movements can be estimated. We apply these methods to different cortical regions (PMd and M1) and compare the proposed compression methods to a random projections strategy often employed for compressed sensing and to a supervised regression based channel dropping strategy traditionally applied in BMI applications.

Incidence and Outcome of Acute Kidney Injury in Patients Hospitalized With Coronavirus Disease-19 at a Tertiary Care Medical Center in Saudi Arabia.

Introduction The systemic acute respiratory syndrome coronavirus (SARS-CoV-2) has been associated with acute kidney injury (AKI). We retrospectively studied the incidence and outcome of AKI in patients hospitalized with COVID-19 at King Abdulaziz Medical City (KAMC) Riyadh, Kingdom of Saudi Arabia. Methods A retrospective cohort study was conducted after ethical approval from the institutional review board of King Abdullah International Medical Research Center (KAIMRC). Subjects were identified by Data Management Office of KAIMRC. The data were extracted from electronic medical records using a customized data collection sheet. The study included all adult patients (>18 years) who tested positive for COVID-19 by polymerase chain reaction and were admitted at KAMC from March 2020 until the end of September 2020. Patients with a history of end-stage kidney diseases and patients where adequate data were not available to establish diagnosis of AKI were excluded. Patient demographics, comorbid conditions, medications, use of mechanical ventilation, and 30-day mortality were recorded. Results During the study period (01 March 2020 to 30 September 2020) 1293 patients were hospitalized at KAMC with the diagnosis of COVID-19. After excluding the patients who met the exclusion criteria, data were collected for 1025 patients [male 582 (56.8%); female 443 (43.2%)]. On univariate analysis, increasing age, male gender, use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, diuretics, and vasopressors, presence of chronic kidney disease, coronary artery disease, chronic obstructive pulmonary disease, dyslipidemia, diabetes mellitus, heart failure, and hypertension, kidney transplant status, and mechanical ventilation were associated with development of AKI. On multivariate logistic regression analysis, independent predictors of AKI were restricted to increasing age, presence of chronic kidney disease, hypertension, kidney transplant status, use of vasopressors, and mechanical ventilation. For patients who developed AKI, 30-day mortality was 40.7% compared to 3.7% for those who did not develop AKI (p<0.001). Conclusion For hospitalized patients with COVID-19, we observed an incidence of AKI of 36%. Increasing age, presence of chronic kidney disease and hypertension, kidney transplant status, use of vasopressors, and mechanical ventilation were independently associated with development of AKI. Presence of AKI was associated with higher 30-day mortality (40.7% vs 3.7%).

Whole body vibration versus magnetic therapy on bone mineral density in elderly osteoporotic individuals.

BACKGROUND: Osteoporosis usually develops gradually and progresses without significant signs and symptoms. It is one of the most common musculoskeletal conditions associated with aging. OBJECTIVES: To evaluate the effects of whole body vibration (WBV) or magnetic therapy in addition to standard pharmacological treatment on bone mineral density (BMD) in elderly individuals being treated for osteoporosis. METHODS: Eighty-five participants, 60-75 years of age, were randomly divided into three groups. All three groups received the same standard pharmacological treatment comprised of vitamin D, calcium, and alendronate sodium. In Group I, thirty participants were also exposed to WBV for 25 minutes in each session with two sessions per week for 4 months. In Group II, thirty participants were exposed to magnetic therapy for 50 minutes in each session with two sessions per week for 4 months. In Group III, twenty-five participants received only pharmacological treatment. Dual-energy X-ray absorptiometry was used to measure BMD of the lumbar spine and femoral heads before and after interventions. Venus blood sample was drawn for analysis of calcium and vitamin D. RESULTS: An ANOVA test detected significant (p< 0.05) differences in BMD after treatment among the three groups with no significant difference was detected between patients receiving WBV and magnetic therapy. Statistical t-tests detected significant (p< 0.05) increases in BMD after application of WBV or magnetic therapy in combination with pharmacological treatment, but no significant increase after pharmacological treatment alone. CONCLUSIONS: Addition of either WBV or magnetic therapy to standard pharmacological treatment for osteoporosis significantly increased BMD in elderly subjects. No significant difference in effectiveness was detected between these two alternative therapy modalities. Consequently, either WBV or magnetic therapy could be effectively applied in conjunction with pharmacological treatment to increase BMD in elderly osteoporotic patients.