Browsing by Author "Lowe, Mark J."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Comparison of rhyming and word generation with FMRI
    (Wiley Open Access, 2000-06-06) Lurito, Joseph T.; Kareken, David A.; Lowe, Mark J.; Chen, Shen Hsing A.; Mathews, Vincent P.; Neurology, School of Medicine
    Functional magnetic resonance imaging (FMRI) has been successfully used to non‐invasively map language function, but has several disadvantages. These include severe motion sensitivity, which limits overt verbal responses in behavioral paradigms, such as word generation. The lack of overt responses prevents behavioral validation, making data interpretation difficult. Our objective was to compare the FMRI activation patterns of a novel silent rhyme determination task requiring a non‐verbal response, to covert word generation from visually presented letters. Five strongly right‐handed subjects performed both tasks during multi‐slice coronal echo‐planar T2*–weighted FMRI. Single subject activation maps were generated for each task by correlation analysis of single pixel time series to a boxcar reference function. These maps for the two tasks were separately interpolated to 2563, transformed into Talairach space, summed, and thresholded at t>6. Combined activation maps from both tasks showed similar robust perisylvian language area activation, including inferior frontal gyrus, posterior superior temporal lobe, and fusiform gyrus. Subjects performed well on the rhyming task, which activated left hemisphere cortical regions more selectively than the word generation task. The rhyming task showed less activation than the word generation task in areas typically not considered specifically related to language function, such as the dorsolateral prefrontal cortex and anterior cingulate. The rhyming task is a useful tool for brain mapping and clinical applications, potentially more specific to cortical language areas than verbal fluency.
  • Thumbnail Image
    Item
    Diffusion-Weighted Imaging of White Matter Abnormalities in Patients with Phenylketonuria
    (American Society of Neuroradiology, 2001-09) Phillips, Micheal D.; McGraw, Peter; Lowe, Mark J.; Mathews, Vincent P.; Hainline, Bryan E.; Radiology and Imaging Sciences, School of Medicine
    Phenylketonuria (PKU) is an autosomal recessive disorder caused by a deficiency of the enzyme phenylalanine hydroxylase (EC 1.14.16.1). Affected patients develop elevated plasma and tissue levels of phenylalanine and its related ketoacids. Untreated patients usually exhibit severe mental retardation and poor motor function, with characteristic T2 white matter signal abnormalities on conventional MR images. In the present study, we performed diffusion-weighted imaging in three PKU patients. All three patients demonstrated significantly restricted diffusion in all white matter areas examined.