Independent component analysis (ICA) has been shown as a promising tool for the analysis of functional magnetic resonance imaging (fMRI) time series. Each of these studies, however, used a general-purpose algorithm for performing ICA and the computational efficiency and accuracy of elicited neuronal activations have not been discussed in much detail. We have previously proposed a direct search method for improving computational efficiency. The method, which is based on independent component-cross correlation-sequential epoch (ICS) analysis, utilizes a form of the fixed-point ICA algorithm and considerably reduces the time required for extracting desired components. At the same time, it is shown that the accuracy of detecting physiologically meaningful components is much improved by tailoring the contrast function used in the algorithm. In this study, further improvement was made to this direct search method by integrating an optimal contrast function. Functional resolution of activation maps could be controlled with a suitable selection of the contrast function derived from prior knowledge of the spatial patterns of physiologically desired components. A simple skewness-weighted contrast function was verified to extract sufficiently precise activation maps from the fMRI time series acquired using a 3.0 Tesla MRI system.

The cortical areas subserving music literacy were investigated using high-field (3 Tesla) functional magnetic resonance imaging (fMRI). The activation pattern associated specifically with music score reading was compared with that associated with reading text in a subject's primary and secondary language. While the areas of activation were predominantly identical for all three reading modalities, there were areas within the occipital cortex activated exclusively by music score reading. Grand analysis of the activation patterns of eight pianists unequivocally identified that the principal cortical area needed for music literacy is the cortex flanking the right transverse occipital sulcus (musical brain).

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Hemispheric specialization is a prominent characteristic of the human brain. Should the 'dominant' hemisphere possess differential neural organization for language production in the 'higher order' cortex, it would be rational to consider that the primary motor cortex may also show similar hemispheric specialization for speech production. In order to test this hypothesis, we investigated the spatial distribution of neural activities associated with phonation (M1p), silent tongue motion (M1t), and vocalization (M1v) within the primary motor cortex, utilizing independent component-cross correlation-sequential epoch analysis of high-field functional magnetic resonance imaging time series. While M1t showed no significant differences between the two hemispheres, M1p and M1v exhibited significant hemispheric differences. The study demonstrated direct evidence that human primary motor cortex possesses clear-cut hemispheric specialization similar to that observed for the higher order cortices.

In seven patients with mucopolysaccharidoses (1 Hurler, 1 Hurler-Scheie, 4 Hunter, 1 Sly), cranial 1 H-magnetic resonance spectroscopy was performed to evaluate the accumulation of mucopolysaccharides and biochemical changes in the CNS in vivo before and after bone marrow transplantation (BMT). In two of seven patients, 1 H-magnetic resonance spectroscopy was performed before and after BMT. Nuclear magnetic resonance spectra of dermatan sulfate and chondroitin sulfate-C and magnetic resonance spectroscopy of chondroitin sulfate-C and urine from patients with mucopolysaccharidoses showed resonance higher than the chemical shift of myoinositol in the brain (3.7 ppm). The resonance was considered to contain signals from mucopolysaccharide molecules. The resonance was measured as presumptive mucopolysaccharides (pMPS). In white matter lesions detected by magnetic resonance imaging, pMPS/creatine ratios and choline/creatine ratios were consistently higher than control ratios. In white matter without lesions, choline/creatine ratios were higher than control ratios. Patients with higher developmental quotient or intelligence quotient tended to show higher N-acetylaspartate/creatine ratios and lower pMPS/ creatine ratios in basal ganglia. After BMT, the pMPS/creatine ratio in white matter lesions of patient 3, with Hunter syndrome, was slightly decreased, but in none of the patients was the ratio ever below the control ratios, even 7 y after BMT. In white matter without lesions, the pMPS/creatine ratio in patient 3 was decreased to the control ratios after BMT, but although the choline/creatine ratios were gradually decreased, they remained higher than the control ratio, 2 y after BMT. These results suggest that evaluation of pMPS, choline, and N-acetylaspartate by