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Abstract Human cognition is characterized by a wide range of capabilities including goal-oriented selective attention, distractor suppression, decision making, response inhibition, and working memory. Much research has focused on studying these individual components of cognition in isolation, whereas in several translational applications for cognitive impairment, multiple cognitive functions are altered in a given individual. Hence it is important to study multiple cognitive abilities in the same subject or, in computational terms, model them using a single model. To this end, we propose a unified, reinforcement learning-based agent model comprising of systems for representation, memory, value computation and exploration. We successfully modeled the aforementioned cognitive tasks and show how individual performance can be mapped to model meta-parameters. This model has the potential to serve as a proxy for cognitively impaired conditions, and can be used as a clinical testbench on which therapeutic interventions can be simulated first before delivering to human subjects.

Parkinson’s disease (PD) is a progressive neurological disorder that is typically characterized by a range of motor dysfunctions, and its impact extends beyond physical abnormalities into emotional well-being and cognitive symptoms. The loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) leads to an array of dysfunctions in the functioning of the basal ganglia (BG) circuitry that manifests into PD. While active research is being carried out to find the root cause of SNc cell death, various therapeutic techniques are used to manage the symptoms of PD. The most common approach in managing the symptoms is replenishing the lost dopamine in the form of taking dopaminergic medications such as levodopa, despite its long-term complications. Another commonly used intervention for PD is deep brain stimulation (DBS). DBS is most commonly used when levodopa medication efficacy is reduced, and, in combination with levodopa medication, it helps reduce the required dosage of medication, prolonging the therapeutic effect. DBS is also a first choice option when motor complications such as dyskinesia emerge as a side effect of medication. Several studies have also reported that though DBS is found to be effective in suppressing severe motor symptoms such as tremors and rigidity, it has an adverse effect on cognitive capabilities. Henceforth, it is important to understand the exact mechanism of DBS in alleviating motor symptoms. A computational model of DBS stimulation for motor symptoms will offer great insights into understanding the mechanisms underlying DBS, and, along this line, in our current study, we modeled a cortico-basal ganglia circuitry of arm reaching, where we simulated healthy control (HC) and PD symptoms as well as the DBS effect on PD tremor and bradykinesia. Our modeling results reveal that PD tremors are more correlated with the theta band, while bradykinesia is more correlated with the beta band of the frequency spectrum of the local field potential (LFP) of the subthalamic nucleus (STN) neurons. With a DBS current of 220 pA, 130 Hz, and a 100 microsecond pulse-width, we could found the maximum therapeutic effect for the pathological dynamics simulated using our model using a set of parameter values. However, the exact DBS characteristics vary from patient to patient, and this can be further studied by exploring the model parameter space. This model can be extended to study different DBS targets and accommodate cognitive dynamics in the future to study the impact of DBS on cognitive symptoms and thereby optimize the parameters to produce optimal performance effects across modalities. Combining DBS with rehabilitation is another frontier where DBS can reduce symptoms such as tremors and rigidity, enabling patients to participate in their therapy. With DBS providing instant relief to patients, a combination of DBS and rehabilitation can enhance neural plasticity. One of the key motivations behind combining DBS with rehabilitation is to expect comparable results in motor performance even with milder DBS currents.

Introduction The coronavirus disease 2019 (COVID-19) pandemic has affected the healthcare system. The residents who are at the frontline of this pandemic have suffered the most. The extent of the training loss due to the COVID-19 pandemic on gastroenterology (GE) training is not studied in India. Methods We designed a 36-question based google survey and distributed it to the GE residents all across India, via email. All the responses collected were analyzed using appropriate statistical methods. Results A total of 140 responses were received. No significant decrease in teaching sessions/ classes was reported. Most of the residents (83.5%) reported inability to complete the target thesis enrolment. The number of patients seen by the residents in outpatient department, patients managed in wards and endoscopic procedures done by residents have decreased significantly (p-valve

In order to understand the link between substantia nigra pars compacta (SNc) cell loss and Parkinson's disease (PD) symptoms, we developed a multiscale computational model that can replicate the symptoms at the behavioural level by incorporating the key cellular and molecular mechanisms underlying PD pathology. There is a modelling tradition that links dopamine to reward and uses reinforcement learning (RL) concepts to model the basal ganglia. In our model, we replace the abstract representations of reward with the realistic variable of extracellular DA released by a network of SNc cells and incorporate it in the RL-based behavioural model, which simulates the arm reaching task. Our results successfully replicated the impact of SNc cell loss and levodopa (L-DOPA) medication on reaching performance. It also shows the side effects of medication, such as wearing off and peak dosage dyskinesias. The model demonstrates how differential dopaminergic axonal degeneration in basal ganglia results in various cardinal symptoms of PD. It was able to predict the optimum L-DOPA medication dosage for varying degrees of cell loss. The proposed model has a potential clinical application where drug dosage can be optimised as per patient characteristics.

Background: Rigid sigmoidoscopy (RS) in the present era of flexible sigmoidoscopies is falling out of favor although it continues to be used in some centers as an outpatient (OP) department procedure. Aims: This study aims to determine the utility of RS for diagnosis of rectosigmoidal pathologies in the OP setting with emphasis on neoplastic lesions. Methods: We retrospectively studied the RS records and histopathology reports (HPRs) of 5 years (July 2013–June 2018) done in the Department of Gastroenterology at Medical College Calicut. Results: During the study period, 9418 RS examinations were done, and a total of 6921 abnormalities were picked up, giving a diagnostic yield of 73.5%. Most common indication was bleeding per rectum (PR) (51%), followed by constipation (29%). The most common lesion found was hemorrhoids 39.8% followed by proctitis 13.7%, neoplasms 9.7%, and others 10.3% while 26.5% studies were normal. HPRs showed 7.7% to be malignant, 5.8% were adenoma, 12.2% were inflammatory bowel disease ulcerative colitis (IBD UC), 2.2% were solitary rectal ulcer syndrome, 1.2% nonspecific colitis, 1.7% nonneoplastic polyps, 2.7% were normal, and 1.4% were inconclusive. Of the 4812 patients with complaints of bleeding PR, 4739 (98.5%) had a diagnosis after RS, of which hemorrhoids (72.7%) was the most common cause followed by proctitis (14.2%), neoplasm (9%), and others (4.1%). The sensitivity, specificity, positive predictive value, and negative predictive value of RS in detecting neoplasia was 98.2%, 96.8%, 66.1%, and 99.9%, respectively, when HPR was gold standard. RS was found to be effective for assessing activity in IBD UC. Conclusion: RS is a simple, cheap, and effective tool for diagnosing various rectosigmoid pathologies. RS can be used as an effective screening test for rectosigmoid pathologies, especially neoplasia and IBD UC.

Background and objectives: Cardiovascular implantable electronic devices (CIED) are frequently implanted in patients on anti-thrombotic agents. Pocket hematomas are more likely to occur in these patients. The use of a sterile surgical drain in the pulse generator pocket site could prevent hematomas, but fear of infection precludes its use. The objective of the present study is to study the safety and efficacy of surgical drain in patients on antithrombotics undergoing CIED implantations. Methods: This is a single-centre, retrospective study involving patients undergoing CIED implantations on antithrombotics (antiplatelets and anticoagulants) from August 2013 to July 2016. Patients with high risk of thromboembolism were continued on oral antithrombotics or were bridged with heparin after stopping oral antithrombotics. A sterile close wound suction drain was placed in device pockets following CIED implantations. Post procedure, pressure dressing was applied and removed after 12 h once the drain volume was less than 10 ml in 24 h. Results: Sixty seven patients required surgical drain implantation. Major indications for antithrombotic use were presence of intracoronary stent, atrial fibrillation and mechanical valve replacements. The mean post-procedural hospital stay was 3 ± 0.9 days and mean overall drain was 16.6 ± 8.2 ml. At a mean follow up of 17.6 ± 8.2 months, one patient (1.4%) had pocket hematoma. There were no infections. Conclusion: The use of a surgical drain in CIED implantation significantly reduces the risk of hematoma formation without increasing the risk of infection. Antithrombotic drugs can be safely continued at the time of implantation of cardiac devices. Keywords: Pocket hematoma, Antithrombotic treatment, Device implantation, Anticoagulation, Antiplatelets, Surgical drain

A 55 year old male presented with recurrent implantable cardioverter defibrillator (ICD) shocks due to polymorphic ventricular tachycardia (PMVT). He had undergone prior catheter ablation for VT three years ago. During the prior attempt he underwent voltage guided substrate ablation. With programmed ventricular extrastimulation (PVES), PMVT was repeatedly induced requiring DC shock. Intravenous procainamide was administered and PVES was repeated which induced sustained monomorphic ventricular tachycardia (MMVT). This VT had pseudo delta waves with maximum deflection index of 0.68, suggestive of epicardial origin. Activation mapping was performed epicardially. Presystolic potentials were recorded in mid anterolateral wall of left ventricular epicardial region. Radiofrequency (RF) ablation at this site terminated the VT. Post ablation there was no inducible tachycardia and patient is free of arrhythmias during 2 years of follow-up.