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Thomas Meigen, Patrick Hottenroth; Lateral interaction mechanisms in texture segregation can be studied with a two-frequency VEP method. Journal of Vision 2006;6(6):203. doi: 10.1167/6.6.203.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. We present a two-frequency method to isolate a lateral interaction component in the human visual evoked potential to texture stimuli (liVEP) and to compare this liVEP to a texture segregation specific VEP component (tsVEP, Bach & Meigen 1992).
Methods. 20 visually normal subjects participated in the study. Vertical bars with either horizontal or vertical dominant orientation were generated by superposition of Gabor patches with random amplitude. For liVEP isolation the dominant orientations of neighboring vertical bars were modulated with different temporal frequencies f1=3.3Hz and f2=2.2 Hz. The Fourier component at the inter-modulation frequency f1+f2=5.5Hz indicates a nonlinear interaction and was used to define the liVEPs. tsVEPs were isolated by linear combination of VEP responses to steady-state stimuli (f=5.5Hz) where the same changes in dominant orientation resulted in an onset or offset of the vertical bars. The significance of the binocularly recorded liVEPs and tsVEPs (criterion p<5%) was quantified by the signal-to-noise ratio in the Fourier domain.
Results. (1) The percentage of significant responses was 85% for liVEPs and 95% for tsVEPs. (2) This difference in percentage was not significant (p>0.25, Cochran-test). (3) The regression analysis showed a highly significant correlation (r=0.90, p<0.0001) between liVEP and tsVEP magnitudes.
Conclusions. The close correlation of liVEP and tsVEP data suggests that liVEPs offer a new method to study lateral interaction mechanisms in texture segregation. liVEPs can be isolated in a single recording and do not require a linear combination of different VEP responses. Thus liVEPs may help to facilitate the electrophysiological investigation of texture segregation.
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