Periods of rest in fMRI contain individual spontaneous events which are related to slowly fluctuating spontaneous activity

fMRI studies of brain activity at rest study slow (<0.1 Hz) intrinsic fluctuations in the blood‐oxygenation‐level‐dependent (BOLD) signal that are observed in a temporal scale of several minutes. The origin of these fluctuations is not clear but has previously been associated with slow changes in rhythmic neuronal activity resulting from changes in cortical excitability or neuronal synchronization. In this work, we show that individual spontaneous BOLD events occur during rest, in addition to slow fluctuations. Individual spontaneous BOLD events were identified by deconvolving the hemodynamic impulse response function for each time point in the fMRI time series, thus requiring no information on timing or a‐priori spatial information of events. The patterns of activation detected were related to the motor, visual, default‐mode, and dorsal attention networks. The correspondence between spontaneous events and slow fluctuations in these networks was assessed using a sliding window, seed‐correlation analysis, where seed regions were selected based on the individual spontaneous event BOLD activity maps. We showed that the correlation varied considerably over time, peaking at the time of spontaneous events in these networks. By regressing spontaneous events out of the fMRI signal, we showed that both the correlation strength and the power in spectral frequencies <0.1 Hz decreased, indicating that spontaneous activation events contribute to low‐frequency fluctuations observed in resting state networks with fMRI. This work provides new insights into the origin of signals detected in fMRI studies of functional connectivity. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Impact of Length of Residence in the United States on Risk of Diabetes and Hypertension in Resettled Refugees

The relationship between resettlement and development of chronic disease has yet to be elucidated in refugees. We aimed to assess the relationship between length of residence in the US and development of diabetes and hypertension utilizing multivariable logistic regression models in a sample of former refugee patients seeking primary care services. Multivariable logistic regression models adjusting for age, gender, and country of origin showed significantly increasing odds of type 2 diabetes (OR 1.12, 95% CI 1.03–1.22, p?<?0.01) and hypertension (OR 1.07, 95% CI 1.00–1.14) with increasing length of stay in the US for resettled refugee adults. A significant proportion of diabetes (26.7%) and hypertension (36.9%) diagnoses were made within one year of arrival, highlighting the critical role of focusing diagnosis and prevention of chronic disease in newly resettled refugees, and continuing this focus throughout follow-up as these patients acculturate to their new homeland.     

Influence of history of smoking on the physical capacity of older people

Among the elderly, smoking is related to death and it contributes to disability associated with chronic diseases. This study aims to verify the influence of a history of smoking on the physical capacity of elderly people, and its relationship with the gender. Elderly people beginning to practice physical activity reported questions about their smoking history and underwent a physical evaluation, consisted by hemodynamic data (blood pressure, heart rate and maximum oxygen consumption), body mass index (BMI), muscular strength, flexibility and balance. Mann-Whitney test and Spearman's test was used to data analysis. The sample consisted of 127 subjects, among whom 26.8% were ex-smokers. There were a higher number of nonsmoking women (p < 0.001) than others, and women smoked fewer packets per day (p = 0.047). Among the women, those ex-smokers were younger and more flexible in comparison with those nonsmokers (p < 0.05). Among the men, the ex-smokers were older and walked more slowly than nonsmokers (p < 0.05). There was a correlation between the BMI and duration of smoking time. Smoking cessation benefits the elderly, since the physical variables showed no long-term harm associated with the history of smoking when compared with those of elderly without this habit.