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Laila Hugrass, David Crewther; The effects of visual surround on multifocal visual evoked potentials. Journal of Vision 2017;17(10):793. doi: 10.1167/17.10.793.
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© ARVO (1962-2015); The Authors (2016-present)
When studying the effects of surround on visual evoked potentials (VEPs), it is important to design experiments that separate responses to the stimulus and surround. Multifocal paradigms allow for fully de-correlated stimulation of different regions of visual space, and previous studies of mfVEPs have shown that components the K2.1 and K2.2 kernels appear to be of magnocellular and parvocellular origins respectively. Hence we propose that the technique could be used to investigate the effects of visual surround, and furthermore could allow for neurophysiological dissection of surround effects. Here we report the results from experiments on the effects of red vs. green surround (N = 15) and parallel vs. orthogonal surround (N = 9) on mfVEPs. In both experiments, the first order evoked responses were unaffected by the surround. For the coloured surround experiment, we observed a significant reduction in the N100-P150 amplitude of the K2.2 response for red cf. green surround (F (1,14) = 10.75, p = .005, partial η2 = .43). This finding suggests that red surrounds may increase the efficiency parvocellular responses. For the orientation experiment, we observed a significant reduction in the N60-P100 K2.1 amplitude with parallel surround at low spatial frequency (t(8) = 2.52, p = .04) but not at high spatial frequency (t(8) = .014, p = .99). This finding is consistent with evidence that orientation selective suppression is a predominantly magnocellular phenomenon. Together, these results indicate that mfVEP is a useful technique for investigating the effects of surround on visual processing.
Meeting abstract presented at VSS 2017
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