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M C Huang

Publications and source records attributed to M C Huang.

78 records · Page 5Linked to original sources
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Quadrature subunits in directionally selective simple cells: counterphase and drifting grating responses.

Here we examine further the basis for directional selectivity (DS) in simple cells of the cat's striate cortex. We use a distinctly different input stimulus and different analysis of the output signal for the same type of space-time inseparable receptive field (RF) that was measured with flashing bars in the companion paper (Emerson, 1997). As in the companion paper, we have mimicked a popular "linear" model with a single "branch" that consists of a linear spatiotemporal filter followed by a soft threshold, which should mimic any simple cells that have a single subunit. Counterphase sinusoidal measurements of such a configuration always generate elliptically shaped polar plots of amplitude versus temporal phase, often pinched along the minor axis because of a high threshold. However, for many spatiotemporal frequencies, such polar phase plots, as measured in simple cells by others, show a consistent rotational phase skew. Here we apply counterphase analysis to the same 2-branch model as developed in the companion paper. We show that the model accounts for the skew as the summation of signals from linear filters separated spatially and temporally by approximately 90 deg (i.e. in spatiotemporal phase quadrature), each separated from the output stage by a soft-threshold nonlinearity. We also prove conclusively that such skew cannot be generated by a single-subunit configuration. This demonstration supports the proposed two-subunit structure for DS simple cells, such as in the example from the companion paper, which has strong linear contributions from its inseparable RF. The presence of at least two nonlinear subunits appears to be an obligatory concomitant of DS in all visual cortical cells. The primary function of these subunits may be to enhance the strength of responses to images moving in the preferred direction, as in complex cells. However, subunits may also aid in identifying the moving object through overcoming, at least partially, the phase-concealing properties of the neuron's threshold by generating a steady signal that effectively decreases the threshold for the preferred direction.

Animals↗
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A follow-up study of genetic counseling in Down syndrome.

To ascertain the effects of genetic counseling on the education of counselees, a questionnaire study on the acceptance of genetic knowledge was carried out among 126 parents of children with Down syndrome. Those parents from the "Down Syndrome Association" had best scores for knowledge, followed by those who had received counseling according to a designed format (programmed counseling) in this Hospital. Parental perceptions of the information needed in genetic counseling were also studied and it was found that most parents thought that the topics of education and medical care were more important than genetic information. Realization of such difference in primary concern between counselors and counselees may improve the effectiveness of genetic counseling.

Analysis of Variance↗
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Comparison of the genetic knowledge among nurses, students, and general public after ten years of implementation of genetic health program in Taiwan.

This study aims to explore the genetic knowledge of different health professional, and non-professional populations after ten years of implementation of genetic health program in Taiwan. A self-administered questionnaire was developed to test the genetic knowledge of 885 respondent who included 361 community health nurses, 74 maternal-child nurses, 364 college students, and 86 members of the general public. The questionnaire included 33 questions which were divided into 4 categories (1) basic genetic knowledge, (2) Mendel's Law and probability, (3) prenatal diagnosis, (4) identification of common genetic disorders. The responses were scored and analyzed statistically with ANOVA tests. Community health nurses had the highest scores of genetic knowledge. However, they need more practice in the application of Mendel's Law and probability. Maternal-child nurses should be involved in genetic education programs and improve their ability to identify common genetic disorders and thus increase their ability to identify cases and provide better information to patients and families. Compared to other groups, college students had lower scores in prenatal diagnosis and identification of common genetic disorders. Therefore, college curricula in genetics need to emphasize more on these subjects. From the study, it was concluded that community health nurses are effective and competent to continue the genetic education as supported by the government in the past ten years. Maternal-child nurses are inevitably involved in genetic service, and they should be provided with suitable continuing education programs. The general public should strengthen their knowledge of prenatal diagnosis and common genetic disorders. Prenatal diagnosis should be added in the school curriculum of college students to expand their knowledge. New genetic technology, such as DNA analysis, should be added in the content of genetic education programs.

Adult↗