The primary motor cortex hand area (M1HAND) and adjacent dorsal premotor cortex (PMd) form the so-called motor hand knob in the precentral gyrus. M1HAND and PMd are critical for dexterous hand use and are densely interconnected via corticocortical axons, lacking a sharp demarcating border. In 24 young right-handed volunteers, we performed multimodal mapping to delineate the relationship between structure and function in the right motor hand knob. Quantitative structural magnetic resonance imaging (MRI) at 3 tesla yielded regional R1 maps as a proxy of cortical myelin content. Participants also underwent functional MRI (fMRI). We mapped task-related activation and temporal precision, while they performed a visuomotor synchronization task requiring visually cued abduction movements with the left index or little finger. We also performed sulcus-aligned transcranial magnetic stimulation of the motor hand knob to localize the optimal site (hotspot) for evoking a motor evoked potential (MEP) in two intrinsic han...

Alzheimer’s disease (AD) is characterized by irreversible memory loss and declining performance across multiple cognitive domains, and is the most common form of dementia accounting for over half of dementia cases worldwide. Magnetic resonance imaging (...

Currently, no in vivo method is available for analyzing the integrity and functionality of the spinal cord in animal models of spinal cord injury (SCI). Damage and recovery are usually assessed by locomotor tests in the living animal or by histology post mortem. The fact that manganese ions mimic calcium and shorten the T1 relaxation time of water protons in magnetic resonance imaging (MRI) has brought them to the in vivo application. Manganese is taken up into cells resulting in a strong contrast enhancement in MRI that indicates neuronal function and activity. We show that intracerebroventricular injection of manganese chloride solution leads to uptake within the complete central nervous system. Following SCI manganese uptake in the spinal cord is reduced. Furthermore, the amount of manganese uptake correlates with the extent of damage as assessed histologically and by clinical locomotor tests. We have previously shown that inhibition of apoptosis by administration of neutralizing antibodies directed aga...

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...

Objective: The caudate may contribute to psychopathological, cognitive deficits in Schizotypal personality disorder (SPD), a schizophrenia spectrum disorder. We also focused on the female as there is evidence to suggest that cognition and psychopathology may differ according to gender in schizophrenia spectrum disorder. Here we examine using Magnetic resonance imaging (MRI) caudate nucleus volume change and cognitive deficits in a sample of female SPD who had no previous neuroleptic exposure and controls. Method: MRI scans obtained on a 1.5 T magnet with 1.5-mm contiguous slices were used to measure the caudate nucleus in 32 right-handed, neuroleptic-naive female subjects with SPD and in 29 normal comparison female subjects. Subjects were group matched for age, parental socioeconomic status and IQ. Results: First, we found significantly lower right and left relative caudate volume (7.6%, 8.4%) in female SPD than in female normal subjects. Second, there were significant, inverse correlations between right r...

Recent advances in magnetic resonance imaging (MRI) technology now allow the tracing of developmental changes in the brains of children. We applied computer-matching algorithms and new techniques for measuring cortical thickness (in millimeters) to the structural MRI images of 45 children scanned twice (2 yr apart) between the ages 5 and 11. Changes in brain size were also assessed, showing local brain growth progressing at a rate of ∼0.4-1.5 mm per year, most prominently in frontal and occipital regions. Estimated cortical thickness ranged from 1.5 mm in occipital regions to 5.5 mm in dorsomedial frontal cortex. Gray matter thinning coupled with cortical expansion was highly significant in right frontal and bilateral parieto-occipital regions. Significant thickening was restricted to left inferior frontal (Broca's area) and bilateral posterior perisylvian (Wernicke's area on the left) regions. In the left hemisphere, gray matter thickness was correlated with changing cognitive abilities. For the first tim...

If rectus extraocular muscle pulleys provide predominantly mechanical determinants of ocular kinematics, then pulley locations should predict behavior. We tested predictions of vertical disconjugacy of the horizontal aVOR in situations where magnetic resonance imaging (MRI) demonstrates horizontal rectus pulley misalignment (Demer et al. JNP 89:2072, 2003). Binocular eye movements were recorded using search coils in humans undergoing transient, whole-body yaw rotation (2,800°/s2 peak) in darkness while fixating straight ahead, as well as ± 20° vertically, at distances of 500 and 15 cm. Four subjects achieved large, uninterrupted horizontal slow phases. During unconverged viewing, MRI shows that the lateral rectus pulley shifts inferiorly relative to medial rectus in up gaze, but superiorly in down gaze. During 500 cm viewing, the eyes rotated 31° horizontally by 275 ms. The adducting eye moved up relative to the abducting eye by 1.39 ± 0.19° (SEM) in up gaze, but 0.71 ± 0.38° downward in down gaze (P < 0.0...

The hippocampus has been implicated in a number of disorders including depression, schizophrenia and Alzheimer's disease. Analysis of hippocampal volume using magnetic resonance imaging (MRI) is emerging as a mainstream technique. The purpose of this study was to analyse the interobserver reliability in determining hippocampal volume using MRI. Contiguous 1.2 mm thick, T1 weighted, 3D fast spoiled gradient echo images were obtained. To calculate the total cerebral volume (TCV) and the volume of the hippocampus, the region was traced on each saggital slice, thus determining area in mm2. The TCV includes all white and grey matter within the dura mater, pituitary, pons, medulla and cerebellum. The structures included in the hippocampal complex are the cornu ammonis, dentate gyrus, subiculum, but not the alveus. The measured areas were summed, then multiplied by a slice thickness of 1.2 mm to give the volume in mm3 for each region. The measurements taken by two observers, S1 and S2, were compared. TCV measured...

Magnetic Resonance Imaging (MRI) provides a noninvasive method for investigating brain morphology. Within the medial temporal lobe, special attention has been paid to the hippocampus (HC) and amygdala (AG) because of their role in memory, depression, emotion, and learning. Volume changes in these areas have been observed in conjunction with certain disease states, e.g. Alzheimer's disease, post-traumatic stress disorder, and depression. Aging has also been shown to result in gray matter volume loss of the overall brain, including the HC. With regard to gender specificity, results suggest a larger shrinkage for men of brain gray matter, with controversial observations being made for the HC. With recently refined MRI acquisition and segmentation protocols, the HC and AG of 80 subjects in early adulthood (39 men and 41 women, age 18–42 years) were investigated. Whereas the volume of the AG appeared to be independent of age and gender, a significant negative correlation with age for both left and right HC was...

Paths of rectus EOMs are constrained by connective tissue pulleys that serve as functional origins and determine EOM pulling directions. Magnetic resonance imaging (MRI) of human EOMs in secondary gaze positions indicates that pulley locations are consistent with the requirement of a linear oculomotor plant (Quaia & Optican, 1998) appearing commutative to its neural controller. In oculocentric coordinates, the distance between the pulley and globe center must equal the distance between globe center and EOM insertion. We have shown that the orbital layer of each EOM inserts on and translates the pulley while only the global layer rotates the eye (Demer et al 2000). MRI in humans was correlated with a geometrical model of EOM actions to show that active control of pulley position by the orbital layer can maintain geometry required by a linear oculomotor plant in tertiary gaze by posterior pulley displacement during EOM contraction. If EOM orbital layers can contract independently of global layers, then pulle...