Exploring the origins of EEG motion artefacts during simultaneous fMRI acquisition: implications for motion artefact correction

Motion artefacts (MAs) are induced within EEG data collected simultaneously with fMRI when the subject’s head rotates relative to the magnetic field. The effects of these artefacts have generally been ameliorated by removing periods of data during which large artefact voltages appear in the EEG traces. However, even when combined with other standard post-processing methods, this strategy does not remove smaller MAs which can dominate the neuronal signals of interest. A number of methods are therefore being developed to characterise the MA by measuring reference signals and then using these in artefact correction. These methods generally assume that the head and EEG cap, plus any attached sensors, form a rigid body which can be characterised by a standard set of six motion parameters. Here we investigate the motion of the head/EEG cap system to provide a better understanding of MAs. We focus on the reference layer artefact subtraction (RLAS) approach, as this allows measurement of a separate reference signal for each electrode that is being used to measure brain activity. Through a series of experiments on phantoms and subjects, we find that movement of the EEG cap relative to the phantom and skin on the forehead is relatively small and that this non-rigid body movement does not appear to cause considerable discrepancy in artefacts between the scalp and reference signals. However, differences in the amplitude of these signals is observed which may be due to differences in geometry of the system from which the reference signals are measured compared with the brain signals. In addition, we find that there is non-rigid body movement of the skull and skin which produces an additional MA component for a head shake, which is not present for a head nod. This results in a large discrepancy in the amplitude and temporal profile of the MA measured on the scalp and reference layer, reducing the efficacy of MA correction based on the reference signals. Together our data suggest that the efficacy of the correction of MA using any reference-based system is likely to differ for different types of head movement with head shake being the hardest to correct. This provides new information to inform the development of hardware and post-processing methods for removing MAs from EEG data acquired simultaneously with fMRI data

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Caffeine Supplementation and Multiple Sprint Running Performance

Purpose: The aim of this study was to examine the effects of caffeine supplementation on multiple sprint running performance. Methods: Using a randomized double-blind research design, 21 physically active men ingested a gelatin capsule containing either caffeine (5 mg·kg-1 body mass) or placebo (maltodextrin) 1 h before completing an indoor multiple sprint running trial (12 × 30 m; repeated at 35-s intervals). Venous blood samples were drawn to evaluate plasma caffeine and primary metabolite concentrations. Sprint times were recorded via twin-beam photocells, and earlobe blood samples were drawn to evaluate pretest and posttest lactate concentrations. Heart rate was monitored continuously throughout the tests, with RPE recorded after every third sprint. Results: Relative to placebo, caffeine supplementation resulted in a 0.06-s (1.4%) reduction in fastest sprint time (95% likely range = 0.04-0.09 s), which corresponded with a 1.2% increase in fatigue (95% likely range = 0.3-2.2%). Caffeine supplementation also resulted in a 3.4-bpm increase in mean heart rate (95% likely range = 0.1-6.6 bpm) and elevations in pretest (+0.7 mmol·L-1; 95% likely range = 0.1-1.3 mmol·L-1) and posttest (+1.8 mmol·L-1; 95% likely range = 0.3-3.2 mmol·L-1) blood lactate concentrations. In contrast, there was no significant effect of caffeine supplementation on RPE. Conclusion: Although the effect of recovery duration on caffeine-induced responses to multiple sprint work requires further investigation, the results of the present study show that caffeine has ergogenic properties with the potential to benefit performance in both single and multiple sprint sports

A preliminary evaluation of shallow-water rhodolith beds in Bahia Magdalena, Mexico

The aim of the present study was to describe the structure of shallow-water rhodolith beds from Bahia Magdalena, one of the most productive estuarine systems of the Mexican Pacific coasts. From September 2008 to May 2009 four rhodolith beds were found (between 1 and 3 m depth) and population descriptors such as rhodolith density, size classes, branch density, volume and weight were determined. The dominant rhodolith forming species was Lithophyllum margaritae. The size of beds ranged from 7,600 to 17,800 m2 approximately with densities from 42.2 to 215.9 ind.m-2. In these beds, L. margaritae shows fruticose and foliose growth forms, from which spherical forms were predominant (81-99%). Branch density (from 3.0 to 13.3 branches.cm-2) varied significantly (p < 0.05) among beds. The average volume (from 2.0 to 400 mL) and wet weight (from 32.4 to 84.8 g) was not significantly different among sites, but a significant positive correlation (r = 0.95, p < 0.05) was found between these parameters. The size of plants ranged from 2.0 to 11.5 cm with predominant size classes of 40.1-60 mm. Differences in rhodolith density, branch density and sphericity were attributed to possible differences in hydrodynamic conditions among sites. These beds were also a suitable habitat for high diversity of associated sponges. A non-metric multidimensional scaling (MDS) analysis using sponge species data revealed variability in the distribution of sponge assemblages among sites, which is likely the result of differences in environmental conditions. Although these rhodolith beds are not as extensive as those of other regions, our preliminary surveys revealed that they are a common habitat in Bahía Magdalena and likely have an important role in the productivity of this estuarine system.<br>O objetivo do presente estudo foi descrever a estrutura de bancos de rodolitos de áreas rasas da Bahia Magdalena, um dos sistemas estuarinos mais produtivos da costa pacífica mexicana. Quatro bancos de rodolitos situados entre 1 e 3m de profundidade foram avaliados em relação a densidade, classes de tamanho, densidade dos ramos, volume e peso no período de setembro de 2008 a maio de 2009. A espécie dominante no local foi Lithophyllum margaritae. O tamanho dos bancos variou de 7,600 a 17,800 m² aproximadamente, com densidades de 42.2-215.9 ind.m-2 . Foram observadas formas de crescimento fruticosa e folhosa em L. margaritae, sendo a forma esférica predominante (81-99%). A densidade dos ramos (3.0-13.3 ramos.cm-2) variou significativamente (p < 0.05) entre os bancos. O volume médio (2.0-400 ml) e o peso úmido (32.4-84.8 g) não tiveram diferenças significativas entre os locais, mas uma correlação positiva significativa (r = 0.95, p < 0.05) foi encontrada entre os parâmetros. O tamanho das plantas variou de 2.0 a 11.5 centímetros predominando o padrão entre 40.1-60 mm. As diferenças na densidade de rodolitos, densidade dos ramos e a esfericidade foram atribuídas às condições hidrodinâmicas diferenciadas nos locais. Estes bancos também foram um importante habitat para uma grande diversidade de esponjas associadas. A ordenação das amostras com o escalonamento multidimensional não-métrico (MDS) indicou grande variabilidade na distribuição das assembléias de esponjas entre os bancos, estas diferen��as provavelmente são resultado de diferenças nas condições ambientais. Embora estes bancos de rodolitos não sejam tão extensos quanto os de outras regiões, nossas pesquisas preliminares revelaram que estes bancos são um habitat comum na Bahia Magdalena e provavelmente têm um papel importante na produtividade do sistema estuarino da região

Global, regional, and national burden of traumatic brain injury and spinal cord injury, 1990-2016 : a systematic analysis for the Global Burden of Disease Study 2016

Background Traumatic brain injury (TBI) and spinal cord injury (SCI) are increasingly recognised as global health priorities in view of the preventability of most injuries and the complex and expensive medical care they necessitate. We aimed to measure the incidence, prevalence, and years of life lived with disability (YLDs) for TBI and SCI from all causes of injury in every country, to describe how these measures have changed between 1990 and 2016, and to estimate the proportion of TBI and SCI cases caused by different types of injury. Methods We used results from the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016 to measure the global, regional, and national burden of TBI and SCI by age and sex. We measured the incidence and prevalence of all causes of injury requiring medical care in inpatient and outpatient records, literature studies, and survey data. By use of clinical record data, we estimated the proportion of each cause of injury that required medical care that would result in TBI or SCI being considered as the nature of injury. We used literature studies to establish standardised mortality ratios and applied differential equations to convert incidence to prevalence of long-term disability. Finally, we applied GBD disability weights to calculate YLDs. We used a Bayesian meta-regression tool for epidemiological modelling, used cause-specific mortality rates for non-fatal estimation, and adjusted our results for disability experienced with comorbid conditions. We also analysed results on the basis of the Socio-demographic Index, a compound measure of income per capita, education, and fertility. Findings In 2016, there were 27.08 million (95% uncertainty interval [UI] 24.30-30.30 million) new cases of TBI and 0.93 million (0.78-1.16 million) new cases of SCI, with age-standardised incidence rates of 369 (331-412) per 100 000 population for TBI and 13 (11-16) per 100 000 for SCI. In 2016, the number of prevalent cases of TBI was 55.50 million (53.40-57.62 million) and of SCI was 27.04 million (24 .98-30 .15 million). From 1990 to 2016, the age-standardised prevalence of TBI increased by 8.4% (95% UI 7.7 to 9.2), whereas that of SCI did not change significantly (-0.2% [-2.1 to 2.7]). Age-standardised incidence rates increased by 3.6% (1.8 to 5.5) for TBI, but did not change significantly for SCI (-3.6% [-7.4 to 4.0]). TBI caused 8.1 million (95% UI 6. 0-10. 4 million) YLDs and SCI caused 9.5 million (6.7-12.4 million) YLDs in 2016, corresponding to age-standardised rates of 111 (82-141) per 100 000 for TBI and 130 (90-170) per 100 000 for SCI. Falls and road injuries were the leading causes of new cases of TBI and SCI in most regions. Interpretation TBI and SCI constitute a considerable portion of the global injury burden and are caused primarily by falls and road injuries. The increase in incidence of TBI over time might continue in view of increases in population density, population ageing, and increasing use of motor vehicles, motorcycles, and bicycles. The number of individuals living with SCI is expected to increase in view of population growth, which is concerning because of the specialised care that people with SCI can require. Our study was limited by data sparsity in some regions, and it will be important to invest greater resources in collection of data for TBI and SCI to improve the accuracy of future assessments. Copyright (C) 2018 The Author(s). Published by Elsevier Ltd.Peer reviewe