Robert Erickson | PubMed Health

PubMed2003

Magnetization transfer contrast imaging in Niemann pick type C mouse liver.

PURPOSE: To investigate livers of mice afflicted with Niemann Pick type C (NP-C) disease using magnetization transfer contrast (MTC) imaging and to test the hypothesis that the MT ratio reproducibly changes during disease progression. BACKGROUND: NP-C is a heritable defect of lipid metabolism that results in the accumulation of unesterified cholesterol and gangliosides in virtually all cells. Symptoms predominate in brain and liver, which have high endogenous rates of lipid turnover. It is fatal to children, usually early in the second decade of life. Previous work has shown that the efficiency of magnetization transfer (MT) can be affected by cholesterol and collagen in tissues. The MT ratio (MTR) was calculated and compared during growth and therapy of diseased and control mice. RESULTS: Significant differences in the MTR were observed between livers of diseased and control mice. These ratios were consistent with collagen deposition associated with fibrosis, and not the accumulation of unesterified cholesterol in this organ. CONCLUSION: These results indicate that MTC imaging may have clinical potential for monitoring progression and therapy in NP-C disease.

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PubMed2003

A model for intracortical visual prosthesis research.

In the field of visual prosthesis research, it has generally been held that animal models are limited to testing the safety of implantable hardware due to the inability of the animal to provide a linguistic report of perceptions. In contrast, vision scientists make extensive use of trained animal models to investigate the links between visual stimuli, neural activities, and perception. We describe an animal model for cortical visual prosthesis research in which novel animal psychophysical testing has been employed to compensate for the lack of a linguistic report. One hundred and fifty-two intracortical microelectrodes were chronically implanted in area V1 of a male macaque. Receptive field mapping was combined with eye-tracking to develop a reward-based training procedure. The animal was trained to use electrically induced point-flash percepts, called phosphenes, in performing a memory saccade task. It is our long-term goal to use this animal model to investigate stimulation strategies in developing a multichannel sensory cortical interface.

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