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120 results on '"Mason, J. L."'

12. A2B5+ and O4+ Cycling Progenitors in the Adult Forebrain White Matter Respond Differentially to PDGF-AA, FGF-2, and IGF-1

Author

Mason, J. L. and Goldman, J. E.

Subjects
*NEUROGLIA, *PROSENCEPHALON, *MITOGENS
Abstract

Cycling glial progenitors reside within subcortical white matter of the mammalian adult forebrain. Either A2B5 or O4 expression defines two of the major classes of cycling progenitors. We examined the growth factor receptor profiles of these progenitor populations and their capability to proliferate and differentiate in response to PDGF-AA, FGF-2, and IGF-1. FGF-2 and IGF-1 enhance the acquisition of O1 by the O4+ progenitors, but have no significant effect on the acquisition of O4 and/or O1 by the A2B5+ progenitors. In contrast, PDGF-AA enhances the acquisition of O1 by the A2B5+ progenitors, while having no significant affect on the acquisition of O1 by the O4+ progenitors unless combined with FGF-2. In addition, PDGF-AA and FGF-2 promote the proliferation of A2B5+ progenitors, while having no mitogenic effect on the O4+ progenitors unless the two factors are combined with IGF-1. Interestingly, not all of the progenitors within the A2B5 or O4 populations express the same growth factor receptors nor respond similarly to growth factors. Thus, there are substantial differences between the two populations and heterogeneity within each of these populations may exist. [Copyright &y& Elsevier]

Published
2002
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13. Acquisition of a 250-word vocabulary through a tactile vocoder.

Author

Brooks, P. L., Frost, B. J., Mason, J. L., and Chung, K.

Abstract

In a previous experiment [P. L. Scilley, ''Evaluation of a vibrotactile auditory prosthetic device for the profoundly deaf,'' unpublished Masters thesis, Queen's University, Kingston, Canada (1980)] two normal subjects learned to identify 70 and 150 words, respectively, using the Queen's Tactile Vocoder. In the present experiment, the most advanced subject continued word learning until a tactile vocabulary of 250 words was acquired. At this point randomized tests were given to obtain an indication of final performance level. From these data conditional probabilities of correct response for each stimulus word and significant confusions were obtained, which provides insight into the advantages and present limitations of the tactile vocoder. [ABSTRACT FROM AUTHOR]

Published
1985
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17. Word and Feature Identification by Profoundly Deaf Teenagers Using the Queen's University Tactile Vocoder

Author

Brooks, P. L., Frost, B. J., Mason, J. L., and Gibson, D. M.

Abstract

The experiments described are part of an ongoing evaluation of the Queen's University Tactile Vocoder, a device that allows the acoustic waveform to be felt as a vibrational pattern on the skin. Two prelingually profoundly deaf teenagers reached criterion on a 50-word vocabulary (live voice, single speaker) using information obtained solely from the tactile vocoder with 28.5 and 24.0 hours of training. Immediately following word-learning experiments, subjects were asked to place 16 CVs into five phonemic categories (voiced & unvoiced stops, voiced & unvoiced fricatives, approximants). Average accuracy was 84.5%. Similar performance (89.6%) was obtained for placement of 12 VCs into four phonemic categories. Subjects were able to acquire some general rules about voicing and manner of articulation cues.

Published
1987
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