Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli

The investigation of distributed coding across multiple neurons in the cortex remains to this date a challenge. Our current understanding of collective encoding of information and the relevant timescales is still limited. Most results are restricted to disparate timescales, focused on either very fast, e.g., spike-synchrony, or slow timescales, e.g., firing rate. Here, we investigated systematically multineuronal activity patterns evolving on different timescales, spanning the whole range from spike-synchrony to mean firing rate. Using multi-electrode recordings from cat visual cortex, we show that cortical responses can be described as trajectories in a high-dimensional pattern space. Patterns evolve on a continuum of coexisting timescales that strongly relate to the temporal properties of stimuli. Timescales consistent with the time constants of neuronal membranes and fast synaptic transmission (5–20 ms) play a particularly salient role in encoding a large amount of stimulus-related information. Thus, to faithfully encode the properties of visual stimuli the brain engages multiple neurons into activity patterns evolving on multiple timescales

Context Matters: The Illusive Simplicity of Macaque V1 Receptive Fields

Even in V1, where neurons have well characterized classical receptive fields (CRFs), it has been difficult to deduce which features of natural scenes stimuli they actually respond to. Forward models based upon CRF stimuli have had limited success in predicting the response of V1 neurons to natural scenes. As natural scenes exhibit complex spatial and temporal correlations, this could be due to surround effects that modulate the sensitivity of the CRF. Here, instead of attempting a forward model, we quantify the importance of the natural scenes surround for awake macaque monkeys by modeling it non-parametrically. We also quantify the influence of two forms of trial to trial variability. The first is related to the neuron’s own spike history. The second is related to ongoing mean field population activity reflected by the local field potential (LFP). We find that the surround produces strong temporal modulations in the firing rate that can be both suppressive and facilitative. Further, the LFP is found to induce a precise timing in spikes, which tend to be temporally localized on sharp LFP transients in the gamma frequency range. Using the pseudo R[superscript 2] as a measure of model fit, we find that during natural scene viewing the CRF dominates, accounting for 60% of the fit, but that taken collectively the surround, spike history and LFP are almost as important, accounting for 40%. However, overall only a small proportion of V1 spiking statistics could be explained (R[superscript 2]~5%), even when the full stimulus, spike history and LFP were taken into account. This suggests that under natural scene conditions, the dominant influence on V1 neurons is not the stimulus, nor the mean field dynamics of the LFP, but the complex, incoherent dynamics of the network in which neurons are embedded.National Institutes of Health (U.S.) (K25 NS052422-02)National Institutes of Health (U.S.) (DP1 ODOO3646

Quinze anos de ecografia intravascular coronária emintervenc ̧ão coronária percutânea em Portugal

INTRODUCTION: Coronary intravascular ultrasound (IVUS) is increasingly important in catheterization laboratories due to its positive prognostic impact. This study aims to characterize the use of IVUS in percutaneous coronary intervention (PCI) in Portugal. METHODS: A retrospective observational study was performed based on the Portuguese Registry on Interventional Cardiology of the Portuguese Society of Cardiology. The clinical and angiographic profiles of patients who underwent PCI between 2002 and 2016, the percentage of IVUS use, and the coronary arteries assessed were characterized. RESULTS: A total of 118 706 PCIs were included, in which IVUS was used in 2266 (1.9%). Over time, use of IVUS changed from none in 2002 to generally increasing use from 2003 (0.1%) to 2016 (2.4%). The age of patients in whom coronary IVUS was used was similar to that of patients in whom IVUS was not used, but in the former group there were fewer male patients, and a higher prevalence of cardiovascular risk factors (hypertension, hypercholesterolemia and diabetes), previous myocardial infarction, previous PCI, multivessel coronary disease, C-type or bifurcated coronary lesions, and in-stent restenosis. IVUS was used in 54.8% of elective PCIs and in 19.15% of PCIs of the left main coronary artery. CONCLUSION: Coronary IVUS has been increasingly used in Portugal since 2003. It is used preferentially in elective PCIs, and in patients with higher cardiovascular risk, with more complex coronary lesions and lesions of the left main coronary artery.info:eu-repo/semantics/publishedVersio

Trends in coronary angioplasty in Portugal from 2002 to 2013 according to the Portuguese National Registry of Interventional Cardiology

INTRODUCTION AND OBJECTIVES: The aim of the present paper was to report trends in coronary angioplasty for the treatment of ST-elevation myocardial infarction (STEMI) in Portugal. METHODS: Prospective multicenter data from the Portuguese National Registry of Interventional Cardiology (RNCI) and official data from the Directorate-General for Health (DGS) were studied to analyze percutaneous coronary intervention (PCI) procedures for STEMI from 2002 to 2013. RESULTS: In 2013, 3524 primary percutaneous coronary intervention (p-PCI) procedures were performed (25% of all procedures), an increase of 315% in comparison to 2002 (16% of all interventions). Between 2002 and 2013 the rate increased from 106 to 338 p-PCIs per million population per year. Rescue angioplasty decreased from 70.7% in 2002 to 2% in 2013. During this period, the use of drug-eluting stents grew from 9.9% to 69.5%. After 2008, the use of aspiration thrombectomy increased, reaching 46.7% in 2013. Glycoprotein IIb-IIIa inhibitor use decreased from 73.2% in 2002 to 23.6% in the last year of the study. Use of a radial approach increased steadily from 8.3% in 2008 to 54.6% in 2013. CONCLUSION: During the reporting period there was a three-fold increase in primary angioplasty rates per million population. Rescue angioplasty has been overtaken by p-PCI as the predominant procedure since 2006. New trends in the treatment of STEMI were observed, notably the use of drug-eluting stents and radial access as the predominant approach