Functional asymmetries in early learning during right,left, and bimanual performance in right‐handed subjects

Purpose:

To elucidate differences in activity and connectivity during early learning due to the performing hand.

Materials and Methods:

Twenty right‐handed subjects were recruited. The neural correlates of explicit visuospatial learning executed with the right, the left hand, and bimanually were investigated using functional magnetic resonance imaging. Connectivity analyses were carried out using the psychophysiological interactions model, considering right and left anterior putamen as index regions.

Results:

A common neural network was found for the three tasks during learning. Main activity increases were located in posterior cingulate cortex, supplementary motor area, parietal cortex, anterior putamen, and cerebellum (IV–V), whereas activity decrements were observed in prefrontal regions. However, the left hand task showed a greater recruitment of left hippocampal areas when compared with the other tasks. In addition, enhanced connectivity between the right anterior putamen and motor cortical and cerebellar regions was found for the left hand when compared with the right hand task.

Conclusion:

An additional recruitment of brain regions and increased striato‐cortical and striato‐cerebellar functional connections is needed when early learning is performed with the nondominant hand. In addition, access to brain resources during learning may be directed by the dominant hand in the bimanual task. J. Magn. Reson. Imaging 2013;37:619–631. © 2012 Wiley Periodicals, Inc.     

BKCa Channel Activation Attenuates the Pathophysiological Progression of Monocrotaline-Induced Pulmonary Arterial Hypertension in Wistar Rats

Cardiovascular Drugs and Therapy - In the present study, the therapeutic efficacy of a selective BKCa channel opener (compound X) in the treatment of monocrotaline (MCT)-induced pulmonary arterial...     

Risk factors associated with the development of ischemic colitis

AIM:To ascertain the role of cardiovascular risk factors,cardiovascular diseases,standard treatments and other diseases in the development of ischemic colitis(IC).METHODS:A retrospective,case-control study was designed,using matched data and covering 161 incident cases of IC who required admission to our hospital from 1998 through 2003.IC was diagnosed on the basis of endoscopic findings and diagnostic or compatible his-tology.Controls were randomly chosen from a cohort of patients who were admitted in the same period and required a colonoscopy,excluding those with diagnosis of colitis.Cases were matched with controls(ratio 1:2),by age and sex.A conditional logistic regression was performed.RESULTS:A total of 483 patients(161 cases,322 con-trols)were included;mean age 75.67±10.03 years,55.9%women.The principal indications for colonos-copy in the control group were lower gastrointestinal hemorrhage(35.4%),anemia(33.9%),abdominal pain(19.9%)and diarrhea(9.6%).The endoscopic findings in this group were hemorrhoids(25.5%),diverticular disease(30.4%),polyps(19.9%)and colorectal cancer(10.2%).The following variables were associated with IC in the univariate analysis:arterial hypertension(P= 0.033);dyslipidemia(P<0.001);diabetes mellitus(P =0.025);peripheral arterial disease(P=0.004);heart failure(P=0.026);treatment with hypotensive drugs(P=0.023);angiotensin-converting enzyme inhibitors;(P=0.018);calcium channel antagonists(P=0.028);and acetylsalicylic acid(ASA)(P<0.001).Finally,the following variables were independently associated with the development of IC:diabetes mellitus[odds ratio(OR)1.76,95%confidence interval(CI):1.001-3.077,P=0.046];dyslipidemia(OR 2.12,95%CI:1.26-3.57,P=0.004);heart failure(OR 3.17,95%CI:1.31-7.68,P=0.01);peripheral arterial disease(OR 4.1,95%CI:1.32-12.72,P=0.015);treatment with digoxin(digitalis)(OR 0.27,95%CI:0.084-0.857,P=0.026);and ASA(OR 1.97,95%CI:1.16-3.36,P=0.012).CONCLUSION:The development of an episode of IC was independently associated with diabetes,dyslipid-emia,presence     

Resting state functional connectivity of the subthalamic nucleus in Parkinson's disease assessed using arterial spin‐labeled perfusion fMRI

Neurophysiological changes within the cortico‐basal ganglia‐thalamocortical circuits appear to be a characteristic of Parkinson's disease (PD) pathophysiology. The subthalamic nucleus (STN) is one of the basal ganglia components showing pathological neural activity patterns in PD. In this study, perfusion imaging data, acquired noninvasively using arterial spin‐labeled (ASL) perfusion MRI, were used to assess the resting state functional connectivity (FC) of the STN in 24 early‐to‐moderate PD patients and 34 age‐matched healthy controls, to determine whether altered FC in the very low frequency range of the perfusion time signal occurs as a result of the disease. Our results showed that the healthy STN was functionally connected with other nuclei of the basal ganglia and the thalamus, as well as with discrete cortical areas including the insular cortex and the hippocampus. In PD patients, connectivity of the STN was increased with two cortical areas involved in motor and cognitive processes. These findings suggest that hyperconnectivity of the STN could underlie some of the motor and cognitive deficits often present even at early stages of the disease. The FC measures provided good discrimination between controls and patients, suggesting that ASL‐derived FC metrics could be a putative PD biomarker. Hum Brain Mapp 36:1937–1950, 2015. © 2015 Wiley Periodicals, Inc .