Although age-related brain volume changes have widely been reported, many questions are yet to be answered. For example, normative data of the brain volume and results of gender and side (left-right) brain volume asymmetry in aging are largely unavailable. In this study, we measured age-related brain volume changes with an automated method. Three-dimensional magnetic resonance images (MRI) of young and old volunteers were collected. The MRI data were quantitatively analyzed by a recently developed automated method. Effects of age, gender, and side on absolute and relative volume measurements of the brain structures were statistically evaluated. Compared to the young group, the elderly subjects showed a 15% volume loss in the whole brain and hemispheres, and a 22% volume loss in the frontal lobes. The coefficient of variation (CV) of the whole brain, hemisphere, and frontal lobe volume measurements were significantly smaller in the old group than in the young group. The relative volume of the left hemispher...

Manganese (Mn)-Enhanced MRI (MEMRI) has been proposed as a method to visualize neuronal activity in animals, taking advantage of the permeability of voltage-gated calcium channels to paramagnetic Mn2+. We tested the sensitivity of MEMRI to detect neuronal activation in the mouse auditory system, imaging mice with T1-weighted MRI at defined time points after intra-peritoneal (IP) injection of MnCl2 (0.2-mmol/kg body weight) and exposure to repetitive auditory stimulation. This easily-implemented protocol resulted in significant (10-15%) MEMRI enhancement in the auditory inferior colliculus (IC) compared to mice with conductive hearing loss, as well as detectable enhancement in the medial geniculate nucleus and primary auditory cortex, but not in the non-auditory striatum. In an attempt to eliminate the problem of inter-animal variability, we also performed MEMRI following unilateral conductive hearing loss, comparing enhancement patterns ipsi- and contra-lateral to the functional ear after repetitive audito...

Global delineation of the spatial distribution of muscle activity is difficult because of the sampling constraints inherent in electromyographic (EMG) activity recordings. A relatively new approach to study this global activity involves the use of dynamic magnetic resonance (MR) images (T2 weighted) pre and post exercise. Because the “gold standard” for measuring muscle activity in humans is monitoring EMG activity, T2 times need to be shown to correlate with EMG activity and behavioral measures (e.g. amount of effort) of activity. Able-bodied subjects carried out concentric ankle plantarflexion contractions against loads equal to 25% and 65% of maximal voluntary contraction (MVC) while EMG activity was recorded from surface electrodes overlying the skin over the lateral gastrocnemius (LG), medial gastrocnemius (MG), peroneal (PER), soleus (SOL) and tibialis anterior (TA) muscles. All subjects had pre and post exercise T2 time measurements and pre-exercise T1 sequences of the right leg while secured in an ...

We have embarked on a series of studies lesioning the amygdala in rhesus monkeys to understand its involvement in mediating fear-related psychopathology. Ibotenic acid lesions are preferable because they allow for selective damage and spare fibers of passage. Since these experiments are long term, relying on traditional histopathological verification of lesion extent is problematic. Therefore, we have been exploring noninvasive methods to determine the accuracy and extent of lesions. To assess the validity of using MRI to verify lesions, T2-weighted images were obtained from 5 monkeys at 1,2, and 3 weeks after lesioning. Approximately 9-12 months after surgery, 40 micron thick histological brain sections were obtained, and the extent of histopathological damage was compared with the one week post-surgery MRI data. A Region-of-Interest (ROI) was drawn around the bright signal region on the T2-weighted MRI (indicative of edema). Then the region of actual tissue loss based on each individual's histological da...

Prior MRI studies have shown cortical gray matter increases in bipolar patients treated with lithium, but it is unknown whether this is related to the disease process. We studied serial structural MRI brain scans (3D SPGR, 1.5 mm slices) from 13 healthy subjects (6F/7M; mean age: 25.5 yrs.+/-10.0SD, scan interval: 4 weeks) treated with 0.5-1.5 mEq/L lithium (a therapeutic dose). To map 3D patterns of local tissue changes over time, an intensity-based elastic registration algorithm deformed the follow-up to the baseline scan by maximizing the mutual information. A tissue change map (the Jacobian of the deformation), for each individual, was nonlinearly normalized to the anatomical space of a reference subject. Mean lithium effects were established by voxel-wise averaging the log-transformed Jacobian maps. Significant tissue hypertrophy was detected. A 2-4% average volume increase was detected in primary sensorimotor and superior frontal regions, consistent with tissue gains localized in prior cortical mappi...

Introduction: We described a parcellation system of the human cerebellar cortex, which is based upon neuroanatomy and conserves the topographic uniqueness of the individual brain [1]. In the present study we created a volume atlas and a surface atlas of the human cerebellar cortex. This was based on nine cerebellar datasets, which have been previously segmented and parcellated. Methods: The cerebellar cortex of nine adult human subjects was segmented and parcellated into 32 parcellation units (PUs) [1, 2] using T1-weighted anatomic MR images. Registration of volumes and surfaces for the nine datasets was performed using the FreeSurfer system [3]. A volumetric and a surface atlas were created based on these nine cerebellar datasets. This resulted in registered grey scale maps and labeled volumetric and surface maps. For every voxel in the average volume maps we generated a probabilistic distribution of the voxel labels. Similarly for every vertex in the average surface maps we obtained a probability of the ...

Manganese-enhanced MRI (MEMRI) is a neuroimaging technique with the potential to differentiate neuronal connectivity and assess temporal responses to stimuli controlling food intake in vivo. It offers many advantages over c-fos expression analysis, generating a real time representation of hypothalamic neuronal activity. Here we employ MEMRI analysis in conjunction with a murine model of appetite stimulation using the orexigenic gut hormone, ghrelin. T1 weighted scans were performed on male C57BL/6 mice in a 9.4T horizontal-bore MR scanner, before and after intravenous (IV) infusion of 100mM MnCl2 and intraperitoneal (IP) administration of ghrelin (0.06 and 0.3 nmol/g body weight) or saline (n = 4-5 /group). The signal intensities (SI) of various hypothalamic nuclei, incuding the arcuate nucleus (ARC), periventricular nucleus (PE) and paraventricular nucleus (PVN), aswell as the ventromedial hypothalamus (VMH), anterior pituitary gland (AP) and 4th ventricle were measured by drawing regions of interest (ROI...

Introduction: By coupling in vivo imaging with post-mortem analysis, we have previously identified an MRI correlate of dentate gyrus neurogenesis in mice. Specifically, we have relied on MRI to estimate cerebral blood volume (CBV) in the dentate gyrus and the CA1 subfields of the hippocampal formation. By adjusting dentate gyrus CBV to CA1 CBV, we were able to reliably predict the degree of cell proliferation in the dentate gyrus of mice exposed to neurogenesis manipulations. Here, we test for this MRI profile in humans with strokes, an established inducer of neurogenesis. Methods: CBV was measured with MRI in the dentate gyrus and the CA1 subfield in subjects with strokes and cognitively-matched controls. Results: Regression analysis showed that dentate gyrus CBV, adjusted for CA1 CBV, was significantly elevated in the stroke group. Secondary analysis showed that dentate gyrus CBV was significantly correlated with a functional measure of activities of daily living. Discussion: The spatial profile of CBV i...

MRI studies have shown dramatic age-associated changes in grey and white matter volume, but typically use univariate analyses that do not explicitly test the interrelationship among brain regions. The current study employed a multivariate approach to identify covariance patterns of grey and white matter tissue density to distinguish older from younger adults. A second aim was to examine whether the expression of these age-associated covariance topographies is related to performance on cognitive tests affected by normal aging. Methods: 84 young (M age=24.0) and 29 older (M age=73.1) participants were scanned with a 1.5 T MRI and assessed with a cognitive battery. Images were spatially normalized and segmented to produce grey and white matter density maps. A multivariate covariance technique, based on the Subprofile Scaling Model, was used to capture sources of between- and within-group variation and to produce a series of principal components (PCs). The analysis identified a linear combination of the PCs th...

It is now well established behaviorally that syncopation (moving antiphase to a pacing stimulus) is intrinsically less stable and requires more attention than inphase synchronization. Recent fMRI results have shown that, relative to synchronization, syncopation results in significant increases in activation of cortical and subcortical areas involved in planning, preparation and timing. We investigated the degree to which this increased activation is altered by practice. Baseline levels of the BOLD response were obtained from eight subjects while they syncopated or synchronized with an auditory metronome at 1.25 Hz. Subjects then practiced syncopation at the same rate while fMR images were acquired continuously. Post practice scans of the two coordination modes were then performed. Before practice, baseline syncopation was associated with significantly greater activation than synchronization in SMA, pre-motor cortices and cerebellum, reflecting the extra planning and timing requirements of syncopation. Acti...