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Cortical responses elicited by luminance and compound stimuli modulated by pseudo-random sequences: comparison between normal trichromats and congenital red-green color blinds.

Risuenho BB, Miquilini L, Lacerda EM, Silveira LC, Souza GS - Front Psychol (2015)

Bottom Line: Trichromats and color-blinds had similar VECP amplitude for compound pattern-reversal K1 and compound pattern-onset K2.2, as well as for all luminance conditions.The cross-correlation analysis showed high similarity between waveforms of compound pattern-onset K2.1 and pattern-reversal K2.2 as well as pattern-reversal K2.1 and K2.2.We suggest that compound pattern-reversal K2.1 is an appropriate response to study red-green color-opponent activity.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciências Biológicas - Universidade Federal do Pará Belém, Brazil.

ABSTRACT
Conventional pattern-reversal visual evoked cortical potential (VECP) shows positivity for luminance and chromatic equiluminant stimuli while conventional pattern-onset VECP shows positivity for luminance pattern-onset and negativity for chromatic pattern-onset. We evaluated how the presentation mode affects VECPs elicited by luminance and compound (luminance plus chromatic) pseudo-random stimulation. Eleven normal trichromats and 17 red-green color-blinds were studied. Pattern-reversal and pattern-onset luminance and compound (luminance plus red-green) gratings were temporally modulated by m-sequence. We used a cross-correlation routine to extract the first order kernel (K1) and the first and second slices of the second order kernel (K2.1 and K2.2, respectively) from the VECP response. We integrated the amplitude of VECP components as a function of time in order to estimate its magnitude for each stimulus condition. We also used a normalized cross-correlation method in order to test the similarity of the VECP components. The VECP components varied with the presentation mode and the presence of red-green contrast in the stimuli. In trichromats, for compound conditions, pattern-onset K1, K2.1, and K2.2, and pattern-reversal K2.1 and K2.2 had negative-dominated waveforms at 100 ms. Small negativity or small positivity were observed in dichromats. Trichromats had larger VECP magnitude than color-blinds for compound pattern-onset K1 (with large variability across subjects), compound pattern-onset and pattern-reversal K2.1, and compound pattern-reversal K2.2. Trichromats and color-blinds had similar VECP amplitude for compound pattern-reversal K1 and compound pattern-onset K2.2, as well as for all luminance conditions. The cross-correlation analysis showed high similarity between waveforms of compound pattern-onset K2.1 and pattern-reversal K2.2 as well as pattern-reversal K2.1 and K2.2. We suggest that compound pattern-reversal K2.1 is an appropriate response to study red-green color-opponent activity.

No MeSH data available.


Compound stimuli. For compound stimulation, we used two chromaticities defined in the CIE 1976 Chromaticity Diagram: red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; (A) For each half cycle of the stimulus, the luminance changed sinusoidally from 5 to 10 cd/m2 and back, at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow, (B). (C) Shows a space-time diagram of the m-sequence configuration for each presentation mode.
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Figure 1: Compound stimuli. For compound stimulation, we used two chromaticities defined in the CIE 1976 Chromaticity Diagram: red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; (A) For each half cycle of the stimulus, the luminance changed sinusoidally from 5 to 10 cd/m2 and back, at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow, (B). (C) Shows a space-time diagram of the m-sequence configuration for each presentation mode.

Mentions: We used two chromaticities for the test with compound gratings, red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; Figure 1A). For each half cycle of the stimulus the luminance changed sinusoidally from 5 to 10 cd/m2 and back at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow (Figure 1B). The chromatic contrast was modulates along a protan confusion line and at about five away from a deutan confusion line in the CIE 1976 color space. The background had the same stimulus yellow mean chromaticity but the luminance was kept at 10 cd/m2 throughout the entire stimulus set. For monitor calibration, we used a CS-100A Colorimeter (Minolta, Osaka, Japan). Compound gratings used in this study was similar but not entirely equal to those used previously by Lee et al. (2011) and Li et al. (2014).


Cortical responses elicited by luminance and compound stimuli modulated by pseudo-random sequences: comparison between normal trichromats and congenital red-green color blinds.

Risuenho BB, Miquilini L, Lacerda EM, Silveira LC, Souza GS - Front Psychol (2015)

Compound stimuli. For compound stimulation, we used two chromaticities defined in the CIE 1976 Chromaticity Diagram: red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; (A) For each half cycle of the stimulus, the luminance changed sinusoidally from 5 to 10 cd/m2 and back, at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow, (B). (C) Shows a space-time diagram of the m-sequence configuration for each presentation mode.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309178&req=5

Figure 1: Compound stimuli. For compound stimulation, we used two chromaticities defined in the CIE 1976 Chromaticity Diagram: red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; (A) For each half cycle of the stimulus, the luminance changed sinusoidally from 5 to 10 cd/m2 and back, at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow, (B). (C) Shows a space-time diagram of the m-sequence configuration for each presentation mode.
Mentions: We used two chromaticities for the test with compound gratings, red (u’ = 0.432, v’ = 0.527) and green (u’ = 0.12, v’ = 0.564; Figure 1A). For each half cycle of the stimulus the luminance changed sinusoidally from 5 to 10 cd/m2 and back at the same time that the chromaticity changed sinusoidally from green or red to the intermediate yellow (Figure 1B). The chromatic contrast was modulates along a protan confusion line and at about five away from a deutan confusion line in the CIE 1976 color space. The background had the same stimulus yellow mean chromaticity but the luminance was kept at 10 cd/m2 throughout the entire stimulus set. For monitor calibration, we used a CS-100A Colorimeter (Minolta, Osaka, Japan). Compound gratings used in this study was similar but not entirely equal to those used previously by Lee et al. (2011) and Li et al. (2014).

Bottom Line: Trichromats and color-blinds had similar VECP amplitude for compound pattern-reversal K1 and compound pattern-onset K2.2, as well as for all luminance conditions.The cross-correlation analysis showed high similarity between waveforms of compound pattern-onset K2.1 and pattern-reversal K2.2 as well as pattern-reversal K2.1 and K2.2.We suggest that compound pattern-reversal K2.1 is an appropriate response to study red-green color-opponent activity.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciências Biológicas - Universidade Federal do Pará Belém, Brazil.

ABSTRACT
Conventional pattern-reversal visual evoked cortical potential (VECP) shows positivity for luminance and chromatic equiluminant stimuli while conventional pattern-onset VECP shows positivity for luminance pattern-onset and negativity for chromatic pattern-onset. We evaluated how the presentation mode affects VECPs elicited by luminance and compound (luminance plus chromatic) pseudo-random stimulation. Eleven normal trichromats and 17 red-green color-blinds were studied. Pattern-reversal and pattern-onset luminance and compound (luminance plus red-green) gratings were temporally modulated by m-sequence. We used a cross-correlation routine to extract the first order kernel (K1) and the first and second slices of the second order kernel (K2.1 and K2.2, respectively) from the VECP response. We integrated the amplitude of VECP components as a function of time in order to estimate its magnitude for each stimulus condition. We also used a normalized cross-correlation method in order to test the similarity of the VECP components. The VECP components varied with the presentation mode and the presence of red-green contrast in the stimuli. In trichromats, for compound conditions, pattern-onset K1, K2.1, and K2.2, and pattern-reversal K2.1 and K2.2 had negative-dominated waveforms at 100 ms. Small negativity or small positivity were observed in dichromats. Trichromats had larger VECP magnitude than color-blinds for compound pattern-onset K1 (with large variability across subjects), compound pattern-onset and pattern-reversal K2.1, and compound pattern-reversal K2.2. Trichromats and color-blinds had similar VECP amplitude for compound pattern-reversal K1 and compound pattern-onset K2.2, as well as for all luminance conditions. The cross-correlation analysis showed high similarity between waveforms of compound pattern-onset K2.1 and pattern-reversal K2.2 as well as pattern-reversal K2.1 and K2.2. We suggest that compound pattern-reversal K2.1 is an appropriate response to study red-green color-opponent activity.

No MeSH data available.