Higher-Order Correlations in Non-Stationary Parallel Spike Trains: Statistical Modeling and Inference

The extent to which groups of neurons exhibit higher-order correlations in their spiking activity is a controversial issue in current brain research. A major difficulty is that currently available tools for the analysis of massively parallel spike trains (N >10) for higher-order correlations typically require vast sample sizes. While multiple single-cell recordings become increasingly available, experimental approaches to investigate the role of higher-order correlations suffer from the limitations of available analysis techniques. We have recently presented a novel method for cumulant-based inference of higher-order correlations (CuBIC) that detects correlations of higher order even from relatively short data stretches of length T = 10–100 s. CuBIC employs the compound Poisson process (CPP) as a statistical model for the population spike counts, and assumes spike trains to be stationary in the analyzed data stretch. In the present study, we describe a non-stationary version of the CPP by decoupling the correlation structure from the spiking intensity of the population. This allows us to adapt CuBIC to time-varying firing rates. Numerical simulations reveal that the adaptation corrects for false positive inference of correlations in data with pure rate co-variation, while allowing for temporal variations of the firing rates has a surprisingly small effect on CuBICs sensitivity for correlations

Medical education and research environment in Qatar: a new epoch for translational research in the Middle East

Recent advances in medical technology and key discoveries in biomedical research have the potential to improve human health in an unprecedented fashion. As a result, many of the Arab Gulf countries, particularly Qatar are devoting increasing resources toward establishing centers of excellence in biomedical research. However, there are challenges that must be overcome. The low profile of private medical institutions and their negligible endowments in the region are examples of such challenges. Business-type government controlled universities are not the solution for overcoming the challenges facing higher education and research programs in the Middle East

Selective and Irreversible Inhibitors of Aphid Acetylcholinesterases: Steps Toward Human-Safe Insecticides

Aphids, among the most destructive insects to world agriculture, are mainly controlled by organophosphate insecticides that disable the catalytic serine residue of acetylcholinesterase (AChE). Because these agents also affect vertebrate AChEs, they are toxic to non-target species including humans and birds. We previously reported that a cysteine residue (Cys), found at the AChE active site in aphids and other insects but not mammals, might serve as a target for insect-selective pesticides. However, aphids have two different AChEs (termed AP and AO), and only AP-AChE carries the unique Cys. The absence of the active-site Cys in AO-AChE might raise concerns about the utility of targeting that residue. Herein we report the development of a methanethiosulfonate-containing small molecule that, at 6.0 µM, irreversibly inhibits 99% of all AChE activity extracted from the greenbug aphid (Schizaphis graminum) without any measurable inhibition of the human AChE. Reactivation studies using β-mercaptoethanol confirm that the irreversible inhibition resulted from the conjugation of the inhibitor to the unique Cys. These results suggest that AO-AChE does not contribute significantly to the overall AChE activity in aphids, thus offering new insight into the relative functional importance of the two insect AChEs. More importantly, by demonstrating that the Cys-targeting inhibitor can abolish AChE activity in aphids, we can conclude that the unique Cys may be a viable target for species-selective agents to control aphids without causing human toxicity and resistance problems

Surgical Treatment for Idiopathic Intracranial Hypertension: Optic Nerve Sheath Fenestration

Venous sinus stenosis has been observed in patients with idiopathic intracranial hypertension (IIH) over the last two decades. Uncertainty remains as to whether this stenosis is the result or cause of intracranial hypertension in certain patients with the disease or whether it may be both. The association of venous sinus stenosis with IIH has led to multiple case reports and retrospective studies detailing the outcomes of patients following venous sinus stenting. The rate of serious irreversible complications appears to be relatively small, but more studies with long-term follow up are needed to fully evaluate its safety. Rates of post-procedure improvement in symptoms, papilledema and visual field defects are promising, but a controlled, prospective trial is needed to properly evaluate its efficacy in stabilizing or reversing symptoms and visual loss in patients with IIH

Pseudo Pseudo Pseudo Tumor Cerebri (Presentation Video)

Blurred vision; Blind spots; Papilledema; HeadacheA 27-year old male with visual disturbances and worsening headache.VA: 20/600 OD, 20/50 OS; RAPD OD; Optic atrophy OD > OS; Field loss OUCT; MRIDural arteriovenous fistulaSurgery; Anticoagulants1. Biondi et al, Evolution of angiographic signs of venous hypertension and clinical signs of intracranial hypertension in intracranial dural arteriovenous fistulas, J Neuroradiol, 26(1), 49-58, 1999. 2. Tsai et al, Intracranial dural arteriovenous fistulas with or without cerebral sinus thrombosis: analysis of 69 patients, J Neurol Neurosurg Psychiatry, 75(11), 1639-41, 2004. 3. Cognard et al, Dural arteriovenous fistulas as a cause of intracranial hypertension due to impairment of cranial venous outflow. J Neurol Neurosurg Psychiatry. 65(3), 308-16, 1998. 4. Kraus et al, Molecular analysis of thrombophilic risk factors in patients with dural arteriovenous fistulas. J Neurol. 249(6), 680-2, 2002

Endovascular Venous Stenting for Idiopathic Intracranial Hypertension (IIH)

Venous sinus stenosis has been observed in patients with idiopathic intracranial hypertension (IIH) over the last two decades. Uncertainty remains as to whether this stenosis is the result or cause of intracranial hypertension in certain patients with the disease or whether it may be both. The association of venous sinus stenosis with IIH has led to multiple case reports and retrospective studies detailing the outcomes of patients following venous sinus stenting. The rate of serious irreversible complications appears to be relatively small, but more studies with long-term follow up are needed to fully evaluate its safety. Rates of post-procedure improvement in symptoms, papilledema and visual field defects are promising, but a controlled, prospective trial is needed to properly evaluate its efficacy in stabilizing or reversing symptoms and visual loss in patients with IIH

Endovascular Venous Stenting for Idiopathic Intracranial Hypertension (IIH)

Venous sinus stenosis has been observed in patients with idiopathic intracranial hypertension (IIH) over the last two decades. Uncertainty remains as to whether this stenosis is the result or cause of intracranial hypertension in certain patients with the disease or whether it may be both. The association of venous sinus stenosis with IIH has led to multiple case reports and retrospective studies detailing the outcomes of patients following venous sinus stenting. The rate of serious irreversible complications appears to be relatively small, but more studies with long-term follow up are needed to fully evaluate its safety. Rates of post-procedure improvement in symptoms, papilledema and visual field defects are promising, but a controlled, prospective trial is needed to properly evaluate its efficacy in stabilizing or reversing symptoms and visual loss in patients with IIH