Detection of Optogenetic Stimulation in Somatosensory Cortex by Non-Human Primates - Towards Artificial Tactile Sensation

Neuroprosthesis research aims to enable communication between the brain and external assistive devices while restoring lost functionality such as occurs from stroke, spinal cord injury or neurodegenerative diseases. In future closed-loop sensorimotor prostheses, one approach is to use neuromodulation as direct stimulus to the brain to compensate for a lost sensory function and help the brain to integrate relevant information for commanding external devices via, e.g. movement intention. Current neuromodulation techniques rely mainly of electrical stimulation. Here we focus specifically on the question of eliciting a biomimetically relevant sense of touch by direct stimulus of the somatosensory cortex by introducing optogenetic techniques as an alternative to electrical stimulation. We demonstrate that light activated opsins can be introduced to target neurons in the somatosensory cortex of non-human primates and be optically activated to create a reliably detected sensation which the animal learns to interpret as a tactile sensation localized within the hand. The accomplishment highlighted here shows how optical stimulation of a relatively small group of mostly excitatory somatosensory neurons in the nonhuman primate brain is sufficient for eliciting a useful sensation from data acquired by simultaneous electrophysiology and from behavioral metrics. In this first report to date on optically neuromodulated behavior in the somatosensory cortex of nonhuman primates we do not yet dissect the details of the sensation the animals exerience or contrast it to those evoked by electrical stimulation, issues of considerable future interest

Einheit von Park und Architektur : der Park am IG Hochhaus

Cerebellar granule cells, which constitute half the brain's neurons, supply Purkinje cells with contextual information necessary for motor learning, but how they encode this information is unknown. Here we show, using two-photon microscopy to track neural activity over multiple days of cerebellum-dependent eyeblink conditioning in mice, that granule cell populations acquire a dense representation of the anticipatory eyelid movement. Initially, granule cells responded to neutral visual and somatosensory stimuli as well as periorbital airpuffs used for training. As learning progressed, two-thirds of monitored granule cells acquired a conditional response whose timing matched or preceded the learned eyelid movements. Granule cell activity covaried trial by trial to form a redundant code. Many granule cells were also active during movements of nearby body structures. Thus, a predictive signal about the upcoming movement is widely available at the input stage of the cerebellar cortex, a

Numerical investigation of a stand alone solar hydrogen energy system effects of PEFC degradation

An existing stand-alone solar energy system producing hydrogen for energy storage is numerically investigated focusing on the degradation of Polymer Electrolyte Fuel Cell (PEFC) and its effects on the overall performance of the system. The system consists of Photovoltaic (PV) panels, polymer electrolyte based electrolyzers, H2 and O2 storage tanks and a commercial PEFC stack. A PEFC is numerically investigated both as new and as degraded (for about two years). Using a variety of observed degradation patterns reported in the literature, the degraded PEFC is parametrically analyzed by using ANSYS Fluent. The investigated parameters are the membrane equivalent weight, the Catalyst Layer (CL) porosity and viscous resistance, the Diffusion Layer (GDL) porosity and viscous resistance, and the bipolar plate contact resistance. By comparing the simulation results for the new and the degraded fuel cells, it is concluded that the effects of overall degradation on cell potential is significant -- being about 20% around the operating point of the fuel cell. This degraded fuel cell is incorporated into the TRNSYS model of the energy system, and then the effects of the PEFC degradation on the performance of the energy system are estimated. It is observed that the degradation has substantial impact on the overall system performance. System down time of approximately one month is possible. Thus, the stand-alone system is not capable of operating continuously for a complete year when the polymer electrolyte based components are degraded

CFD Modeling and Analysis of a Shell-and-Tube Heat Exchanger

A shell-and-tube heat exchanger is modeled and numerically analyzed using a commercial finite volume CFD package. The heat exchanger is small, has a single shell and a single tube pass, and its shell side is baffled. The baffles are 25% or 36% cut single-segmental baffles. Tube layout is the staggered layout with a triangular pitch. There is no leakage from baffle orifices and no gap between the baffles and the shell. It is observed that the shell side flow and the temperature distributions are very sensitive to modeling choices such as mesh, order of discretization and turbulence modeling. Various turbulence models are tried for the first and second order discretizations using two different mesh densities. CFD predictions of shell side pressure drop and overall heat transfer coefficient are obtained and compared with Kern and Bell-Delaware method results. After selecting the best modeling approach, the sensitivity of the results to flow rates and the baffle spacing is investigated. It is observed that the flow and temperature fields obtained from CFD simulations can provide valuable information about the parts of the heat exchanger design that need improvement. Correlation based approaches may indicate the existence of the weakness but CFD simulations can also pin point the source and the location of it. Using CFD together with experiments may speed up the design process and may improve the final design

Effects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: A pilot study

1st International Probiotics Prebiotics and Functional Food Congress -- APR 11-14, 2013 -- Antalya, TURKEYWOS: 000349080900010PubMed ID: 25599776Background/Aims: Although probiotics have been extensively studied in irritable bowel syndrome, data on the impact of probiotics on chronic constipation are scarce. We aimed to evaluate the effects of kefir, which is a probiotic fermented milk product, on the symptoms, colonic transit, and bowel satisfaction scores of patients with chronic constipation. Materials and Methods: Twenty consecutive patients with functional constipation according to the Rome II criteria were divided into two groups based on their colon transit studies: 1. The normal transit (NT) group (n=10); and 2. The slow transit (ST) group (n=10). After a baseline period, 500 mL/day of a probiotic kefir beverage was administered to all patients for 4 weeks. Defecation parameters (stool frequency, stool consistency, degree of straining, laxative consumption) were recorded in diaries daily by the patients. Bowel satisfaction scores were assessed using a visual analog scale. The colon transit study was repeated in the ST group at the end of the study. Results: At the end of the study, the patients showed an increased stool frequency (p<0.001), improved stool consistency (p=0.014), and decreased laxative consumption (p=0.031). The degree of straining during evacuation showed a tendency to improve after kefir administration; however, this was not statistically significant (p=0.18). A repeat transit study showed an acceleration of colonic transit in the ST group (p=0.013). Bowel satisfaction scores also improved (p<0.001). Conclusion: This pilot study shows that kefir has positive effects on the symptoms of constipation. Our results also suggest that kefir improves bowel satisfaction scores and accelerates colonic transit. Controlled trials are warranted to confirm these findings

Comparison of imaging modalities for detection of residual fragments and prediction of stone related events following percutaneous nephrolitotomy

Introduction Achieving stone free status (SFS) is the goal of stone surgery. In this study it is aimed to compare effectiveness of unenhanced helical computerized tomography (UHCT), KUB and ultrasonography (US) for detection of residual RFs and predicition of stone releated events following percutaneous nephrolitotomy (PNL). Materials and Methods Patients underwent PNL for radiopaque stones between November 2007 and February 2010 were followed. Patients were examined within 24-48 hours after the procedure by KUB, US and UHCT. For stone size 4 mm was accepted as cut off level of significance.Sensitivity and specificity of KUB and US for detection of RFs and value of them for prediction of stone related events were calculated. Results SFS was achieved in 95 patients (54.9%) and when cut off value of 4 mm for RFs was employed, SFS was achieved in 131 patients (75.7%). Sensitivity was 70.5% for KUB, and 52.5% for US. UHCT was shown to be significantly more efficient for detection of RFs compared to both KUB (p=0.01) and US (p=0.001). When cut off level of 4 mm employed, sensitivity of KUB and US increased to 85.7% and 57.1%. Statistical significant superiority of UHCT still remained (p value vs. KUB: 0.03 and p value vs. US: 0.008). Conclusion UHCT is the most sensitive diagnostic tool for detecting RFs after PNL. It has higher sensitivity regardless of stone size compared to KUB and US. Additionally UHCT has higher capability of predicting occurrence of stone related events

The Early Impact of COVID-19 Pandemic on Surgical Urologic Oncology Practice in Turkey: Multi-Institutional Experience From Different Geographic Areas.

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