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AbstractHeart failure patients (HF) exhibit deficient heart rate variability patterns during sleep, inappropriate blood pressure responses to evoked challenges, and sleep-disordered breathing patterns, suggesting central regulatory disturbances of autonomic and respiratory control. We examined signal changes in neural sites recruited during a cold pressor challenge to the forehead. A series of 20 image slices (25 volumes, Echo Planar technique) through the brain of 5 HF patients (32-59 yrs), all with sleep-disordered breathing, and 20 healthy control subjects (29-66 yrs) was collected during 1 min baseline and 1.5 min application of a bag of cold (3°C) deuterium oxide to the forehead in a GE 1.5T Signa scanner. Images collected during baseline and challenge conditions were spatially normalized and subjected to a random-effects analysis using the SPM imaging package. Signal changes were significantly diminished in paravermal cerebellar and hippocampal areas of HF patients over controls. We speculate that cerebellar...Nov 7, 2002
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AbstractAlthough transient airway constrictions occur during sleep both in normal and obstructive sleep apnea (OSA) subjects, neural mechanisms that maintain upper airway patency appear not to be activated, or are recruited with sufficient delay to be ineffective in OSA patients. To evaluate these mechanisms, a series of 20 image slices (25 repetitions, Echo Planar technique) through the entire brain was collected during 1 min baseline and 1.5 min expiratory (8 controls, 12 OSA) and inspiratory (10 Controls, 6 OSA) loading challenges in a GE 1.5T Signa scanner. Ages of Controls were 29-62; OSA ages were 29-66. Images were subjected to fixed effects analysis using the SPM imaging package. Areas recruited in both control and patient groups included deep cerebellar nuclei, putamen, and hippocampus. The OSA group showed significantly more dispersion of areas with signal changes, including the orbital frontal cortex, multiple cerebellar regions, and widespread diencephalic sites. In certain forebrain areas, a delayed o...Nov 12, 2001
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AbstractIdentifying the magnocellular (M) and parvocellular (P) parts of human lateral geniculate nucleus (LGN) has been challenging yet remains an important goal because of the different functional properties of these pathways in the brain. Previous research u...Nov 10, 2021
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While resting-state functional magnetic resonance imaging can probe intrinsic network connectivity in both human and rodent brain, behavioral modulation of these connectivity patterns has not yet been demonstrated in the rodent due to the requirements of immobilization or anesthesia for MRI scanning. To enable the effects of behavioral tasks on functional connectivity to be measured in freely moving, awake rats, implanted carbon paste electrodes (CPEs) were used to monitor low-frequency fluctuations of tissue oxygenation. Rats were implanted with CPEs in two nodes of the default mode network (DMN) and two nodes in a lateral cortical network, revealing amperometric oxygen correlation patterns consistent with imaging studies. Using a block design study where rats alternated between sustained periods of instrumental response and unscheduled spontaneous behavior, task-induced decreases in functional connectivity were observed between the DMN node pair, but not in the distinct lateral cortical network, demonstr...Jan 14, 2015
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Previous work has identified axonal outgrowth and/or guidance defects in the brain and spinal cord of prenatal Frizzled3 ( Fz3 )–/– mice. To systematically explore the axonal defects in Fz3 – / – mice and to compare techniques for the global assessment of axon tracts in the developing mouse, we have analyzed wild-type and Fz3 – / – brains using (1) diffusion tensor magnetic resonance imaging (μDTI), (2) neurofilament staining, and (3) two genetically directed neuronal labeling methods. Confirming and extending the previous work of Wang et al. ([2002][1]), we find that the following structures/tracts are absent or greatly reduced in the Fz3 – / – brain: the anterior commissure, cerebral peduncle (corticospinal tract), corpus callosum, fornix, internal capsule (thalamocortical and corticothalamic tracts), stria medullaris, stria terminalis, and hippocampal commissure. An aberrant U-shaped fiber bundle immediately caudal to the optic tract connects the left and right sides of the Fz3 – / – thalamus and likely...Jan 11, 2006
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AbstractAs it is the case worldwide, marijuana (cannabis) use in the United States and Canada is highly prevalent and societal views of its use are changing rapidly, as are the policies that govern the legality of its recreational and medical use. With the rece...Oct 23, 2019
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Experiments using functional magnetic resonance imaging (fMRI) have revealed that the ventral and lateral occipitotemporal cortices (VOTC and LOTC, respectively), areas often associated with high-level visual processing ([Grill-Spector and Malach, 2004][1]), show preferential activation during theJan 13, 2016
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AbstractNeural implants such as electro-corticography devices (ECoGs) are used to identify the seizure foci in drug-resistant epilepsy, or eloquent brain regions in tumor resections. Current devices used in the clinic comprise a thick silicone shell (0.5-2 mm),...Oct 22, 2019
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AbstractBy acquiring super-resolution MRI of ex-vivo brains, we had constructed a full 3D anatomical atlas of the marmoset brain. Version 1 contained the cortical parcellation, and version 2 the white matter pathways. However, these two previous versions were b...Oct 23, 2019
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AbstractNoninvasive brain imaging is much needed for the study of the pathophysiology of neurological disorders, such as stroke. Magnetic resonance imaging (MRI) provides high-resolution morphological images useful in diagnostic radiology to differentiate between normal and abnormal/pathological states in brains. However, there is a lack of noninvasive method to directly measure and map oxygen concentration in the brain, in vivo and in real time, allowing estimates of oxygen distribution. Here we have developed the electron paramagnetic resonance image (EPRI) technique to map oxygen distribution in the ischemic brain of mice. EPRI is a magnetic resonance technique to detect paramagnetic species such as free radicals. As oxygen can broad the linewidth of EPR spectra of nitroxides via spin-spin exchange, we can detect oxygen concentration by analyzing the changes of linewidth of the nitroxides. To map oxygen distribution in the brain, we used a newly synthesized BBB permeable nitroxides, acetoxymethyl ester of 3-car...Nov 15, 2005