In order to clarify the roles played by the primary motor cortex and the supplementary motor area in the execution of complex sequential and simple repetitive finger movements, regional cerebral blood flow (rCBF) was measured with PET using 15O-labelled water in five normal subjects. The PET data of each individual subject co-registered to his own MRI, was analysed. Compared with the resting condition, the mean rCBF was markedly increased in the contralateral sensorimotor cortex (M1-S1) and moderately increased in the contralateral cingulate gyrus and putamen in both the simple and complex motor tasks. During the complex motor task, in addition to the above, the mean rCBF was markedly increased in the supplementary motor area and the contralateral premotor area, and moderately increased in the ipsilateral M1-S1 and cerebellum. In the supplementary motor area, there was a moderate rCBF increase also during the simple task. However, comparison of the mean rCBF increase against the resting condition between the two tasks revealed a greater increase during the complex task than in the other only in the supplementary motor area and the ipsilateral M1-S1. Thus, in agreement with our previous electrophysiological findings, not only the supplementary motor area but also the M1-S1 seems to play an important role in the execution of complex sequential finger movements.

Gold nanoparticles (Au NPs) are a potential x-ray computed tomography (CT) contrast agent. A biocompatible and bioinactive surface is necessary for application of gold nanoparticle to CT imaging. Polyethylene glycol (PEG)-attached dendrimers have been used as a drug carrier with long blood circulation. In this study, the Au NPs were grown in the PEGylated dendrimer to produce a CT contrast agent. The Au NPs were grown by adding gold ions and ascorbic acid at various equivalents to the Au NP-encapsulated dendrimer solution. Both size and surface plasmon absorption of the grown Au NPs increased with adding a large number of gold ions. The x-ray attenuation of the Au NPs also increased after the seeded growth. The Au NPs grown in the PEG-attached dendrimer at the maximum under our conditions exhibited a similar CT value to a commercial iodine agent, iopamidol, in vitro. The Au NP-loaded PEGylated dendrimer and iopamidol were injected into mice and CT images were obtained at different times. The Au NP-loaded PEGylated dendrimer achieved a blood pool imaging, which was greater than a commercial iodine agent. Even though iopamidol was excreted rapidly, the PEGylated dendrimer loading the grown Au NP was accumulated in the liver.

No abstract

To elucidate the functional localization and somatotopic organization of pain perception in the human cerebral cortex, we studied the regional cerebral blood flow using positron emission tomography during selective painful stimulation in six normal subjects. Response to a painful stimulus was elicited using a special CO2 laser, which selectively activates nociceptive receptors, to the hand and foot. Multiple brain areas, including bilateral secondary somatosensory cortices (SII) and insula, and the frontal lobe and thalamus contralateral to the stimulus side, were found to be involved in the response to painful stimulation. While our data indicate that the bilateral SII play an important role in pain perception, they also indicate that there is no pain-related somatotopic organization in the human SII or insula.

No abstract