The gradient echo-echo planar imaging (GRE-EPI) sequence is widely used in functional magnetic resonance imaging (fMRI) studies. However, it causes severe signal loss at the boundaries of organs of different magnetic susceptibility, especially with a high Tesla scanner. Frahm et al. (1988) proposed a z-shim method that reduces signal loss by reconstructing one image from multiple images, each acquired with a refocusing gradient pulse (RGP) of different strength. However, this technique has been applied to fMRI studies infrequently, owing to the difficulty in taking a large number of images with different RGPs while maintaining a practical sampling frequency, and the number of slices required. Here, we propose an effective and practical z-shim method. In the pre-scanning process, a number of image volumes (16-32) is taken with RGP strengths covering the range from 30% to 170% of the default value in steps of 4 - 9%. Then a limited number (around 5) of optimal RGP strengths is chosen, by observing the signal...

Week of April 15, 2019: Read the Latest Advocacy and Science News

Introduction: Simultaneous Electroencephalography and functional Magnetic Resonance Imaging recording (EEG-fMRI) is a multimodal neuroimaging tool that intends to assess the electrophysiological and hemodynamic correlates of brain activity. Despite effo...

Simultaneously recorded electroencephalography and functional magnetic resonance imaging (EEG-fMRI) is a highly informative imaging technique for brain function, but there exists little information about the data quality and safety when used with newer ...

Vagal nerve stimulation (VNS) is FDA approved for epilepsy, depression, cluster headache, and migraine with over 100,000 patients having received VNS implants to date. However, clinical studies suggest that activation of vagus afferent pathways for ther...

The olfactory system is indicated as a route for drug delivery to the brain. The study was conducted to map functional connections of the olfactory system in vivo using magnetic resonance imaging (MRI) and manganese as a transport-mediated tracer. Six male rats were imaged by 1.5T MRI with a bird-cage coil and 3D-SPGR pulse sequence at pre-injection, and 24, 36, 48, and 72 hours post injection of MnCl2 into the right nasal cavity. Images were coregistered, pixel-intensity normalized, and stereotactically transformed to a rat brain atlas, then averaged across subjects using fully automated image analysis software (NEUROSTAT). Images at each time were compared to pre-injection using a one-sample t-statistic on a pixel-by-pixel basis in 3-D and converted to Z maps. Identical imaging was done in a rat after stereotaxic radiofrequency lesioning of the lateral olfactory tract (LOT) at +2.2 mm anterior to Bregma (b.). Significant transport of Mn was observed in the bulb bilaterally (z=39.8 for ipsilateral (ip.) t...

In the last ten years, numerous neurobiological studies have been conducted on Internet addiction or Internet use disorder. Various neurobiological research methods—such as magnetic resonance imaging; nuclear imaging modalities, including positron emiss...

Motor adaptation is crucial for performing accurate movements in a changing environment and relies on the cerebellum. Although cerebellar involvement has been well characterized, the neurochemical changes in the cerebellum underpinning human motor adaptation remain unknown. We used a novel magnetic resonance spectroscopic imaging (MRSI) technique to measure changes in the inhibitory neurotransmitter GABA in the human cerebellum during visuomotor adaptation. Participants ( n = 17, six female) used their right hand to adapt to a rotated cursor in the scanner, compared with a control task requiring no adaptation. We spatially resolved adaptation-driven GABA changes at the cerebellar nuclei and cerebellar cortex in the left and the right cerebellar hemisphere independently and found that simple right-hand movements increase GABA in the right cerebellar nuclei and decreases GABA in the left. When isolating adaptation-driven GABA changes, we found that GABA in the left cerebellar nuclei and the right cerebellar ...

Introduction: Simultaneous Electroencephalography and functional Magnetic Resonance Imaging recording (EEG-fMRI) is a multimodal neuroimaging tool that intends to assess the electrophysiological and hemodynamic correlates of spontaneous and evoked brain...

Magnetic resonance imaging (MRI) provides a unique combination of structural and functional information of the living brain non-invasively, thus yielding information about the where of the brain's information processing. In order to understand, however, also the how of the brain's information processing, it is of central importance to map the pattern of the neuronal connectivity in the same non-invasive manner. In this study, we have utilized the technique of the high-resolution Diffusion Tensor Imaging (DTI) in combination with a 3D fiber reconstruction algorithm to assess the pattern of thalamocortical and cortico-cortical axonal connectivity in cat visual cortex. Cats were initially anesthetized and kept under anesthesia using standard protocols adapted from single unit and optical imaging studies. A surface coil was used. MR experiments were performed on a 4.7-T/31cm (Oxford, UK) horizontal MRI scanner. The MR imaging parameters were: data matrix = 128×64×32; single-shot EPI, FOV = 26 × 26 × 16 mm, TE ...