Parkinson’s Disease (PD) is a disabling neurodegenerative disorder that affects seven to ten millions of people worldwide. It is characterized by chronic progression of motor and cognitive dysfunction resulting from the loss of dopaminergic neurons. The...

In this study we investigated which brain structures are activated when the visual and vestibular systems receive contradictory head rotation information. Using a 1.5T scanner, we acquired T2* weighted single shot gradient echo EPI functional scans (TR/TE 3750/50ms, 124 volumes, matrix size 64x64, slice thickness 4mm) during a caloric stimulation paradigm (120 ml water of 20 degrees Celsius in 15 seconds). The image data was processed with SPM-99 on both single-subject and group analysis level. Each subject participated in two experiments, one with the eyes closed (vestibular input only) and one with the eyes open (vestibular and visual input). The caloric stimulation was quite effective and lead to a sense of rotation in all subjects, especially when the eyes were open. With the eyes closed, activation was seen in several cortical areas, corroborating previous reports in the literature, but not in the cerebellum. However, with the eyes open, activation was observed in several cortical areas, that partiall...

Functional magnetic resonance imaging (fMRI) studies in humans have hitherto failed to demonstrate activity changes in the direct vicinity of transcranial magnetic stimulation (TMS) that cannot be attributed to re-afferent somatosensory feedback or a spread of excitation. In order to investigate the underlying activity changes at the site of stimulation as well as in remote connected regions we applied short trains of high-intensity (110% of resting motor threshold) and low-intensity (90% of active motor threshold) repetitive TMS (rTMS; 3 Hz, 10 s duration) over the presumed location of the left dorsal premotor cortex (PMd) during fMRI. Signal increases in the direct vicinity of the stimulated PMd were observed during rTMS at 110% RMT. However, positive BOLD MRI responses were observed with rTMS at both 90% and 110% RMT in connected brain regions such as right PMd, bilateral PMv, supplementary motor area, somatosensory cortex, cingulate motor area, left posterior temporal lobe, cerebellum, and caudate nucl...

Cerebral microvascular dysfunction significantly contributes to early cognitive impairment and dementia. Here we analyzed blood-brain barrier (BBB) permeability and cerebral blood flow (CBF) in relation to early cognitive decline in APOE3-homozygotes (ε...

The well-known arcuate fasciculus that connects the posterior superior temporal region with the language production region in the ventrolateral frontal cortex constitutes the classic peri-Sylvian dorsal stream of language. A second temporofrontal white matter tract connects ventrally the anterior to intermediate lateral temporal cortex with frontal areas via the extreme capsule. This temporofrontal extreme capsule fasciculus (TFexcF) constitutes the ventral stream of language processing. The precise origin, course, and termination of this pathway has been examined in invasive tract tracing studies in macaque monkeys, but there have been no standard protocols for its reconstruction in the human brain using diffusion imaging tractography. Here we provide a protocol for the dissection of the TFexcF in vivo in the human brain using diffusion magnetic resonance imaging (MRI) tractography which provides a solid basis for exploring its functional role. A key finding of the current dissection protocol is the demon...

Heart 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...

Although 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...

The classical model of the cochlea views it as a “spectral analyzer” made of a “dispersive transmission line” where different frequency components travel at different speeds (travelling wave). The basilar membrane (BM) is topographically organized so th...

Twenty six subjects (M, stdev) 13 young (26.4, 4.8 y.o, 13 old (68.9, 3.1 y.o.) participated in an olfactory memory study and performed two functional Magnetic Resonance Imaging runs (1.5 Tesla MR scanner, Siemens, Anat: 1x1x1mm3, Func: 26 axial EPI sli...

Understanding MRI changes of post-mortem human brain during fixation is key to the comprehension of ex vivo MRI-histology studies. Changes in MRI contrast and relaxation times reflect changes in tissue properties. Those changes are progressive since the...