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J Siegfried

Publications and source records attributed to J Siegfried.

141 records · Page 8Linked to original sources
PubMedDate not supplied

Effects of check size on visual cortex activation studied by functional magnetic resonance imaging.

We studied functional magnetic resonance imaging (fMRI) of visual cortex during checkerboard visual stimulation with three standard check sizes to examine whether activation in the visual cortex varied among these sizes. We acquired fMRI at 1.5 T in 8 normal subjects, each receiving the best refractive correction. Each subject underwent an experiment consisting of four conditions: black and white checkerboards with three check sizes (0.25-, 0.5-, and 1.0-degree) flickering at 8 Hz, and a black screen. SPM96 was used for a group data analysis with a random effects model after each of the subject's data was motion-corrected and spatially normalized to a standard brain. The activation in the visual cortex showed the greatest signal changes with the 0.5-degree check among the three check sizes. When standard check sizes are used to stimulate visual cortex in fMRI experiments, our results suggest that 0.5-degree checks flickering at 8 Hz produce the most vigorous activation in visual cortex.

Adult↗
PubMedDate not supplied

A therapeutic approach and objective test in the treatment of tremor.

Medical treatment of tremor is deceptive. The biochemical disturbance causing its appearance is not known, so that no specific treatment can be applied. Many substances have been proposed for their antitremulant properties, but clinical results must be interpreted with caution as tremor is a labile symptom which is under many influences. The authors have analysed the clinical effect of an interesting antitremulant drug and have reported an original method for measuring tremor.

Adolescent↗