The apoliprotein E (ApoE) e4 allele has been labeled a risk factor for late onset Alzheimer’s disease and has been associated with a greater rate of brain atrophy in healthy older adults (E.M. Reiman, A. Uecker, R.J. Caselli, S. Lewis, D. Bandy, M.J. de Leon, S. De Santi, A. Convit, D. Osborne, A. Weaver, S.N. Thibodeau, Ann Neurol., 44, 288-291) as well as abnormally low rates of glucose metabolism in younger adults bearing one e4 allele (E.M. Reiman, K. Chen, G.E. Alexander, R.J. Caselli, D. Bandy, D. Osborne, A.M. Saunders, J. Hardy, Proc Natl Acad Sci USA, 101, 284-289). To date, no studies have addressed the effects of ApoE on brain development in a pediatric population. The longitudinal nature of our study allows us to track the correlation of ApoE genotype with brain volumes at different ages, possibly elucidating the effects of this gene over time. 292 healthy subjects (age range 6 to 22 years) were recruited for participation in an ongoing longitudinal magnetic resonance imaging (MRI) study at the...

Previous studies have indicated that amputation or deafferentation of a limb induces functional changes in sensory (S1) and motor (M1) cortices, related to phantom limb pain. However, the extent of cortical reorganization after lower limb amputation in patients with nonpainful phantom phenomena remains uncertain. In this study, we combined functional magnetic resonance (fMRI) and diffusion tensor imaging (DTI) to investigate the existence and extent of cortical and callosal plasticity in these subjects. Nine “painless” patients with lower limb amputation and nine control subjects (sex- and age-matched) underwent a 3-T MRI protocol, including fMRI with somatosensory stimulation. In amputees, we observed an expansion of activation maps of the stump in S1 and M1 of the deafferented hemisphere, spreading to neighboring regions that represent the trunk and upper limbs. We also observed that tactile stimulation of the intact foot in amputees induced a greater activation of ipsilateral S1, when compared with cont...

Brain hypoxia/ischemia (H/I) triggers several pathophysiological mechanisms, which contribute to the neuronal damage in immature brain. An important regulator of post-ischemic inflammation as well as pro- and anti-apoptotic gene expression is the transcription factor nuclear factor kappa-B (NF-κB), which has been shown to be involved in models of ischemic insults of the adult brain. However, very little is known about the role of NF-κB and its role in ischemia models of neonatal brain. We therefore studied the effect of pyrrolidine dithiocarbamate (PDTC), an established inhibitor of NF-κB, which previously has been found to be protective in adult brain ischemia, in a rat model of neonatal brain hypoxia/ischemia (H/I). Exposure to H/I produced brain infarcts as evidenced by T2- weighed magnetic resonance imaging (T2-MRI) 7 days after the insult in P7 Wistar rats. A single dose (50 mg/kg, i.p.) of PDTC 2 hours after the H/I insult reduced the mean brain infarct size by 59 %. Immunohistochemical analysis of H...

d-Amphetamine has been proposed to improve the recovery rate of beam walking ability after traumatic or ablation lesions in the sensori-motor cortex. The aim of this study is to investigate how postacute amphetamine treatment effect the recovery after a stroke like brain lesion. Male Sprague Dawley rats weighing 200 to 240 g were used in the study. A focal pan-necrotic lesion was made in the sensori-motor cortex using a photochemical lesion technique. Sensori-motor recovery was recorded daily for 14 days using beam walking as a behaviour test and a non parametric rating scale (1= unable, 7 = normal). A single dose d-amphetamine was administered i.p. 24 h after the lesion using the following doses and groups, 0.5 (n=8), 2.0 (n=8), 5.0 mg/kg (n=6) respectively, and saline as the control group (n=10). Magnetic resonance imaging (MRI) was performed 48 h after the lesion using a Biospec Avance 4.7T scanner. T2- Proton density- (PD) and apparent diffusion coefficient (ADC)-maps were calculated and evaluated. Usi...

Abnormalities of the corpus callosum (CC) have been observed in fetal alcohol syndrome (FAS), from subtle size reductions to complete agenesis. The purpose of this study was to investigate abnormalities not only in the size of the CC, but also in its shape and location within the brains of FAS subjects, and individuals prenatally exposed to alcohol but without FAS (PEA group). Magnetic resonance imaging (MRI) and surface-based image analytic methods were used to study the CC in twenty alcohol-exposed subjects (ALC; 7 with PEA and 13 with FAS; age 8 to 22 years) and 21 controls (8 to 25 years). Measures of verbal learning and visuospatial abilities were also acquired. Results indicate that in addition to CC area reductions most severe in the splenium, the CC is significantly displaced in the ALC group, lying more anterior and inferior, 5 to 7 mm out of place in posterior regions. These findings are robust in the FAS patients, and a similar, but less severe pattern is observed in the PEA group. Notably, the ...

Background and Objectives: The Yucatan minipig model has increasingly been used as a large animal model of SCI. However, in vivo imaging using this model is lacking. Our goal is to investigate the role of MRI biomarkers in prognosticating recovery follo...

Small animal imaging is an important tool for preclinical drug research as it can provide valuable information of disease progression and treatment longitudinally. In this study, we have applied translational imaging techniques to compare neuroinflammat...

Accurate perception of the direction of gravity relies on the integration of multisensory information, particularly from the visual and vestibular systems, within the brain. Although a recent study of patients with cerebellar degeneration suggested a cerebellar role in visuo-vestibular interaction in the perception of gravitational direction, direct evidence remains limited. To address this gap, we conducted two experiments with 42 healthy participants to evaluate the impact of repetitive 1 Hz transcranial magnetic stimulation (rTMS) over the posterior cerebellar vermis on visual dependency, quantified by the subjective visual vertical bias induced by rotating optokinetic stimulation (OKS). Electric field simulations in high-resolution generic head models were used to ensure focal stimulation of the cerebellum at the group level. The results demonstrated that the rTMS applied to the vermis significantly attenuated the OKS-induced shift in visual vertical (SVV) bias. This effect was not observed when stimul...

The cerebral association cortex is organized into networks that are distributed across frontal, parietal, temporal and midline association zones. Analysis of functional MRI (fMRI) data from repeatedly sampled individuals reveals that canonical networks,...

NVM is an open source software tool for making precise neuroanatomical measurements in MRI. SegMentor is a feature of this software that explicitly defines and embeds measurement methods into the tool by providing on-line, context-sensitive instructions and definitions, and also by assisting in making the measurements. SegMentor records, plays, and allows viewing and editing of scripts that provide information to the user and also control the rest of the program. We present the results of a study to analyze the effectiveness of SegMentor for increasing the reliability and decreasing the time necessary for making precise neuroanatomical measurements. By analyzing the same brain scans with and without using SegMentor, we show improvements in both accuracy and efficiency: using SegMentor increases the repeatability and decreases the cost to obtain quantitative MRI brain measurements.