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X Zhang; A Multifocal VEP paradigm for Simultaneously Recording Flash, Pattern Reversal, Temporal Interaction and Spatial Interaction Responses . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4739.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To evaluate a paradigm that allows the simultaneous recording of a multifocal flash VEP (1st order), reversal VEP (2nd order kernel or temporal interaction VEP), pattern reversal VEP and spatial interaction VEP. Methods:The paradigm contained two extensions of Sutter's m-sequence method . First, each stimulus patch was composed of two parts modulated with mutually orthogonal m-sequences. At any moment, each stimulus patch could be in 4 states: both parts white [ww], part 1 white and part 2 black [wb], [bw] and [bb]. Second, multiple independent m-sequences were combined to derive the significant responses. Comparison experiment: Monocular mfVEPs were obtained from 4 normal subjects within a single run using the new paradigm. Similar mfVEPs were also recorded with the VERIS system  using two separate paradigms (flash and pattern reversal) under the same conditions. The display was a scaled, 30-sector, dartboard array 45 degrees in diameter. Each stimulus lasted 2 frames (23.5ms). Electrodes were placed at the inion (I), 4 cm above I, and 1 cm above and either 4 cm to the left or the right of I. Each condition was recorded in two 6.4-min runs. Inset experiment: Monocular mfVEPs were obtained from the 4 subjects. The display was a 4-by-4 grid of patches each with 4 by 4 checks. An insets placed between the checks was either 0, 4, 8 or 16'. Each stimulus lasted 4 frames (47ms). Results:1. The pattern reversal response (mfPVEP)was identical to the equivalent response from the VERIS system. 2. The flash mfVEP was small in both cases. 3. The spatial interaction mfVEP was very large and had a different waveform and amplitude distribution across the visual fields than did the mfPVEP. 4. When the inset between the checks is increased, the spatial interaction mfVEP became smaller while the temporal interaction VEP remained approximately the same. Conclusion:. The paradigm introduced here allows for the recording of a spatial interaction mfVEP in addition to the more standard flash and pattern-reversal mfVEPs. 1. Sutter (1991) SIAM J. Comput. 2.Baseler & Sutter (1994) Vis Res.
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