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Color Responses (color + response)
Selected AbstractsColor responses of the human lateral geniculate nucleus: selective amplification of S-cone signals between the lateral geniculate nucleno and primary visual cortex measured with high-field fMRIEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2008Kathy T. Mullen Abstract The lateral geniculate nucleus (LGN) is the primary thalamic nucleus that relays visual information from the retina to the primary visual cortex (V1) and has been extensively studied in non-human primates. A key feature of the LGN is the segregation of retinal inputs into different cellular layers characterized by their differential responses to red-green (RG) color (L/M opponent), blue-yellow (BY) color (S-cone opponent) and achromatic (Ach) contrast. In this study we use high-field functional magnetic resonance imaging (4 tesla, 3.6 × 3.6 × 3 mm3) to record simultaneously the responses of the human LGN and V1 to chromatic and Ach contrast to investigate the LGN responses to color, and how these are modified as information transfers between LGN and cortex. We find that the LGN has a robust response to RG color contrast, equal to or greater than the Ach response, but a significantly poorer sensitivity to BY contrast. In V1 at low temporal rates (2 Hz), however, the sensitivity of the BY color pathway is selectively enhanced, rising in relation to the RG and Ach responses. We find that this effect generalizes across different stimulus contrasts and spatial stimuli (1-d and 2-d patterns), but is selective for temporal frequency, as it is not found for stimuli at 8 Hz. While the mechanism of this cortical enhancement of BY color vision and its dynamic component is unknown, its role may be to compensate for a weak BY signal originating from the sparse distribution of neurons in the retina and LGN. [source] Determination of Total Protein Content in Gelatin Solutions with the Lowry or Biuret AssayJOURNAL OF FOOD SCIENCE, Issue 8 2006P. Zhou ABSTRACT:, Gelatins can be obtained from different sources and prepared using different processes, and the end product gelatin may vary in amino acid composition and molecular weight distribution. In the present study, the variation in "protein color" development among gelatins in colorimetric total protein content measurements was investigated at 540 nm using the Biuret assay and at 650 nm using the Lowry assay, with bovine serum albumin as the reference protein. In both the Biuret and Lowry assays, the color response varied significantly among gelatins. The difference in imino acid content was the major factor responsible for this variation, which probably influenced the gelatin helix , coil phase transition and resulted in the difference in gelatin associate state. Based on their "protein color" development abilities in both Biuret and Lowry, gelatins were classified into 2 major groups with the hierarchical cluster analysis: 1 group included all cold water fish gelatins, while the other included gelatins from warm water fish, avian, and mammalian species. [source] Colloidal Films That Mimic CiliaADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Fang Liu Abstract Cilia are wavy hair-like structures that extend outward from surfaces of various organisms. They are classified into two general categories, primary cilia, which exhibit sensing attributes, and motile cilia, which exert mechanical forces. A new poly(2-(N,N -dimethylamino)ethyl methacrylate- co -n-butyl acrylate- co - N,N -(dimethylamino) azobenzene acrylamide) (p(DMAEMA/nBA/DMAAZOAm) copolymer is prepared using colloidal synthesis, which, upon coalescence, form films capable of generating surfaces with cilia-like features. While film morphological features allow the formation of wavy whiskers, the chemical composition of the copolymer facilitates chemical, thermal, and electromagnetic responses manifested by simultaneous shape and color changes as well as excitation wavelength dependent fluorescence. These studies demonstrate that synthetically produced polymeric films can exhibit combined thermal, chemical, and electromagnetic sensing leading to locomotive and color responses, which may find numerous applications in sensing devices, intelligent actuators, defensive mechanisms, and others. [source] A quantitative network model for color categorization,COLOR RESEARCH & APPLICATION, Issue 4 2002K. Okajima Abstract To clarify the higher-order mechanism of human color perception, we measured the color appearances of 78 colored lights by an elemental color-scaling method and by a categorical color naming method. The colors covered nearly the entire CIE 1931 xy -chromaticity diagram with three different surrounds. The results showed that firm basic color zones derived by categorical color naming can be mapped with no overlap in an opponent-color response space. We propose a network model with a threshold selector, maximum selectors, and multiplication units with gain factors to generate the categorical color responses quantitatively from the elemental color responses. The model can predict the categorical color naming results in different surround conditions with no change of parameters. This suggests that a nonlinear color vision mechanism for color categorization exists between the primary visual cortex (V1) and the inferior temporal cortex (IT) in the human brain. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 225,232, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10060 [source] | ||||||||||