Introduction: Most previous pharmacological MRI (phMRI) studies have used hypothesis-driven approaches for data analysis. However, the temporal pattern of brain response to a drug injection is not precisely known and head motion associated with drug administration can confound the results. Independent component analysis (ICA) is a data-driven method that does not require a priori knowledge about signal response patterns. In this study, we used group ICA to analyze phMRI BOLD data following cocaine and methylphenidate (MP) administration. Methods: Nine cocaine users received 3 IV drug injections (20mg/70kg cocaine, 10 and 20mg/70kg MP injected over 30sec). During each of 3 scan sessions, subjects received one IV injection of drug and 1 of saline. Whole brain BOLD images were acquired from 4 minutes before to 34 minutes after injection using a modified EPI sequence. A fast ICA algorithm was utilized to analyze the temporally concatenated functional data. An image voxel in an ICA component map was considered ...

Over 1.5 million cases of TBI are reported annually in the U.S., yet reliable tools for prognosis of persistent symptoms following mild TBI are elusive. Diffuse Axonal Injury (DAI) is the most common form of damage, yet current MRI techniques cannot quantify DAI, limiting prognosis and treatment. We present a method to quantitatively evaluate the integrity of white matter tracks reproducibly. The Reproducible Objective Quantification Scheme (ROQS) presents guidelines for selection of 15 reproducible Regions of Interest (ROI) based on anatomically identifiable structures. These ROI are applied to Diffusion Tensor Imaging (DTI) to provide estimates of anisotropy indices and diffusion coefficients. This same method is also applied to Magnetization Transfer Imaging (MTI), which provides a normalized measure (MT Ratio) of the amount of signal suppression that correlates to the type of matter being imaged. Normal volunteers (n=25) were imaged using DTI and MTI to establish population parameters for each ROI. Int...

Introduction: Rapid progress in the development of real time MRI imaging of specific nerve projections in the CNS has been made in the last few years. Of particular interest has been the demonstration of MnCl2 as an MRI contrast agent enabling visualisation of specific axonal pathways in the nervous system. We report here for the first time in vivo transynaptic transport of MnCL2 in the visual system of rats demonstrated with MRI. Materials and Methods: Adult inbred Fisher rats (n=4) were subjected to unilateral intravitreal injection of 2 ul of 100 mM MnCl2 with all procedures in accordance to national local authority regulations. MRI was performed at 2.35 T using a Bruker Biospec Avance DBX-100 (Bruker AG, Germany), with a 72 mm volume coil for transmission and an actively decoupled quadrature rat head surface coil for receive-only. Water-cooled BGA-12 (200 mT/m) gradients were used. The MRI protocol was according to Brekken et al. 2003. Results: MRI performed 36 hours post-injection demonstrated specifi...

Monitoring metabolic changes during ischemia with 1H-MRS may provide additional insights into the efficacy and the mechanism of potential neuroprotective agents. Pyruvate is an endogenous glucose metabolite, which shows substantial neuroprotective effects against several brain insults. However, the mechanism is still not fully understood. As an attempt to gain some insights, in the present study, we examined with MRS the effect of pyruvate in a rat model of permanent MCAO. Under general anesthesia, MCA was permanently occluded with fire-polished suture materials. Ischemic and non-ischemic contralateral brain regions (3 x 3 mm square with 2.5 mm thickness) were subjected to 1H-MRS. Pyruvate (125 mg/kg) was given intraperitoneally 30 min after the occlusion of MCA. In addition to MRS measurements, MR imagings, including diffusion-weighted imaging and T2-weighted imaging, were evaluated at 1, 2, and 6 hours following the ischemic onset. 24 h after MCAO, rats were sacrificed and their brains were stained with ...

Advances in functional imaging have allowed to investigate neuroanatomical correlates of sexual arousal (SA) in a noninvasive manner. Objective: To identify the neuroanatomical correlates of SA of healthy men presented with sexually stimulating photographs. Methods: in ten healthy men, functional magnetic resonance imaging was used to study brain responses to the presentation of highly arousing and of nonsexually arousing photographs representing women. Immediately after the fMRI run, rating scales were presented to subjects to assess perceived SA. Volumetric penile plethysmography was performed during scans. Results: both rating scales and plethysmography demonstrated SA in response to sexually stimulating photographs. Regions that were more activated in response to the sexually arousing than to the neutral photographs included bilaterally the fusiform gyri, the inferior occipital gyri, the superior and the inferior parietal lobules, the thalami, the right precentral gyrus, the left caudate body, the righ...

The complex environment we live in makes it necessary to distinguish relevant from irrelevant information constantly and reliably. The aim of the present study was to investigate the neural substrate underlying the selection of task-relevant information. We devised a new paradigm in which participants had to switch between two different tasks that were instructed by task cues. The task cues had a relevant and an irrelevant cue dimension. In congruent trials, both cue dimensions indicated the same task; in incongruent trials, they indicated different tasks; and in neutral trials, only the relevant dimension indicated a task. By comparing trials in which both cue dimensions were informative (congruent and incongruent trials) with trials in which only the relevant dimension was informative (neutral trials), we were able to show that the lateral prefrontal cortex and a region in the intraparietal sulcus are involved in the selection of task-relevant information. Furthermore, the present paradigm allows the inf...

The KIBRA gene has been associated with episodic memory in several recent reports; carriers of the T-allele show enhanced episodic memory performance relative to noncarriers. Gene expression studies in human and rodent species show high levels of KIBRA in the hippocampus, particularly in the subfields. The goal of the present study was to determine whether the KIBRA C→T polymorphism is also associated with volume differences in the human hippocampus and whether specific subfields are differentially affected by KIBRA genotype. High-resolution magnetic resonance imaging (T2-weighted, voxel size = 0.4 × 0.4 mm, in-plane) was used to manually segment hippocampal cornu ammonis (CA) subfields, dentate gyrus (DG), and the subiculum as well as adjacent medial temporal lobe cortices in healthy carriers and noncarriers of the KIBRA T-allele (rs17070145). Overall, we found that T-carriers had a larger hippocampal volume relative to noncarriers. The structural differences observed were specific to the CA fields and DG...

Evidence from both human and animal studies has demonstrated a key role for brainstem centers in the control of ascending nociceptive input. Nuclei such as the rostral ventromedial medulla and periaqueductal gray (PAG) are able to both inhibit and facilitate the nociceptive response. It has been proposed that altered descending modulation may underlie many of the chronic pain syndromes (both somatic and visceral). We used functional magnetic resonance imaging to image the neural correlates of visceral and somatic pain within the brainstem. Ten healthy subjects were scanned twice at 3 tesla, during which they received matched, moderately painful, electrical stimuli to either the midline lower abdomen or rectum. Significant activation was observed in regions consistent with the PAG, nucleus cuneiformis (NCF), ventral tegmental area/substantia nigra, parabrachial nuclei/nucleus ceruleus, and red nucleus bilaterally to both stimuli. Marked spatial similarities in activation were observed for visceral and somat...

Stereological estimates of human cortex and whole brain volumes at autopsy reveal only slight age-related changes. Autopsied brains from patients suffering neurological disease, including acquired immunodeficiency syndrome (AIDS) and Alzheimer's disease (AD), show significant loss (atrophy) of cortical and whole brain volumes compared to age-matched controls, with strong correlation to dementia scores in AD (Mouton et al., 1998). Early detection of brain atrophy would improve understanding of the time course of neurodegeneration and accelerate the therapeutic management of these diseases. We used high-resolution magnetic resonance imaging (MRI) to visualize hippocampal and whole brain volumes of mice double transgenic for two mutant proteins associated with AD (amyloid precursor protein and presenilin-1). Young and aged dtg APP/PS1 and wild-type (WT) mice were imaged by spin-echo T1-weighted MRI techniques. Total volumes of hemispheres (Vbrain) and hippocampal formation (VHF) were estimated from systematic...

Ischemia causes long-term effects on brain volume and cognitive function, but the relationship between the two is poorly characterized and conflicting. Some studies found whole brain volume to be associated with deficits in cognitive function, while others did not. In the present study, we investigated the relation of MRI-derived normalized whole brain volume and cerebrovascular disease markers with cognitive performance in ischemic stroke patients. 108 subjects with ischemic stroke were included. Cognitive function was evaluated with tests covering global cognitive status, memory, attention, spatial reasoning, language and psychomotor skills. MRI scans were acquired in a 1.5T scanner using a T1 weighted 3D SPGR pulse sequence. Whole brain (WBV), total intracranial (TIV), lateral ventricle (LVV) and stroke (STV) volumes were derived with the Analyze software (Mayo Clinic, Rochester, MN). WBVs were normalized by dividing with TIV. Ventricle-to-brain ratios (VBR) were calculated as a measure of atrophy. We f...