This review article summarises the research on the motion-onset visual evoked potentials (VEPs) and important motion stimulus parameters which have been clarified. For activation of the visual motion processing system and evocation of the motion-onset specific N2 peak (with latency of 160-200ms) from the extra-striate temporo-occipital and/or parietal cortex, the following stimulus parameters can be recently recommended: low luminance (

This study deals with the effect of stimulus contrast, between 1.3% and 96%, on the visual evoked potentials (VEPs) for onset of motion and for pattern reversal of checkerboard stimuli. The VEPs for pattern reversal and for the onset of motion both contain an initial positive peak (P1; peak latency about 120 msec) followed by a later negative peak (N2; peak latency 160-200 msec). However the P1 peak dominates the pattern-reversal VEP when recorded from the midline occipital lead, where it is maximal, while the N2 peak is larger in the motion-onset VEP, especially when recorded from unipolar lateral occipital leads. Whereas the amplitude of the P1 peak in both the pattern-reversal VEP and the motion-onset VEP decreases with decreasing contrast (becoming undetectable at a contrast of about 2% for the motion-onset VEP), the amplitude of the N2 peak in both types of VEP does not vary significantly with contrast, above a contrast of 1.3%. The increase in peak latency with decreasing contrast is also more pronounced for the positive than the negative peaks of both types of VEP. Taking into account the high contrast sensitivity of the magnocellular system (thought to be involved in the processing of motion) compared with the parvocellular system (probably more concerned with the processing of form), our findings suggest that for both motion-onset and pattern-reversal VEPs the negative peak is attributable to the motion-processing magnocellular pathway and the positive peak to the form-processing parvocellular system.

Motion-onset visual evoked potentials were studied in 140 subjects by means of motion-onset stimulation either on a television screen or through back projecting via a moving mirror. The motion-onset visual evoked potentials were characterized in 94% of the population by a dominant negative peak with latency in the range of 135-180 ms. Motion-onset visual evoked potentials with a dominant positive peak, as described in the literature, seemed to be a variant of pattern-off visual evoked potentials, caused by the pattern-disappearance effect at the onset of motion with a high temporal frequency (the multiple of the spatial frequency of the structure and the velocity of motion) of more than 6 Hz. Such visual evoked potentials occur mainly when the stimulus is limited to the macular area only. Additionally, other stimulus and recording conditions were found to be suitable for acquiring the specific motion-onset potentials without their contamination by pattern-related components. These conditions were as follows: an aperiodic moving pattern (e.g., random dots) with a low contrast (less than 0.2); a short duration of motion (less than or equal to 200 ms) and a sufficient interstimulus interval (at least five times longer than the motion duration) to decrease the adaptation to motion; and extramacular stimulation and recording of visual evoked potentials from unipolar lateral occipital leads. Such leads should be used because of the lateralization of these visual evoked potentials (mainly to the right occipital area), which is consistent with their assumed extrastriate origin.

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Pattern-reversal and motion-onset visual evoked potentials (VEPs) were simultaneously tested in a group of 70 healthy subjects between the ages of 6-60 years to verify suspected differences in maturation and aging dynamics of the pattern and motion processing subsystems of the visual pathway. The motion-onset VEPs displayed dramatic configuration development and shortening of latencies up to 18 years of age (correl. coeff. -0.85; p < 0.001) and systematic prolongation from about 20 years of age (correl. coeff. 0.70; p < 0.001). This confirms long-lasting maturation of the magnocellular system and/or motion processing cortex and their early age related changes. Less significant changes of pattern-reversal VEPs in the tested age range can be interpreted as a sign of early maturation of the parvocellular system and its enhanced functional endurance in the elderly.

Reliable motion-onset visual evoked potentials (result of the dorsal stream activation) were recorded to motion stimuli with the temporal frequency of five cycles per seconds in 20 different locations with eccentricity up to 42 degrees to periphery of the visual field. Amplitudes and latencies of the positive-negative-positive (P1-N1-P2; 84-144-208 ms) complex were evaluated in occipital (OZ and two derivations 5 cm to the left and right from OZ) and central region (CZ) in 10 subjects. We observed: (1) Shortening of the N1 latency toward periphery of the visual field. (2) The N1 amplitude maximum and latency minimum moved from occipital into central region (CZ derivation) as stimulus moved from centre toward periphery of visual field. (3) The P1 and N1 peaks displayed significantly greater amplitudes and shorter latencies when the lower part of the visual field was stimulated. (4) The N1 peak changed lateralisation of its maximum amplitude in dependence on the eccentricity. Up to 17 degrees, it corresponds to striate projection of the "optic radiation" whilst more in periphery, there was paradoxical lateralisation of higher amplitude and shorter latency. The retinotopic dependence shows that the motion response includes position information and that the motion-onset VEPs are not generated solely in the higher extrastriate areas (MT or MST).

Visual evoked potentials (VEPs) produced by pattern reversal were compared with those elicited by onset of motion in 37 amblyopic children (20 with anisometropic amblyopia, seven with strabismic amblyopia and 10 with both anisometropia and strabismus). The amplitudes and peak latencies of the main P1 peak in the pattern-reversal VEP and of the motion-specific N2 peak in the motion-onset VEP through the amblyopic eye were compared with those through the normal fellow eye. Regardless of the type of amblyopia, the amplitude of the pattern-reversal VEP for full-field stimulation was significantly smaller and its latency significantly longer through the amblyopic eye (P < 0.001). In contrast, neither the amplitudes nor the latencies of the N2 motion-onset VEPs differed significantly between amblyopic and non-amblyopic eyes. For pattern-reversal VEPs through the amblyopic eyes, the extent to which amplitude was reduced and latency prolonged correlated well with the reduction of visual acuity, whereas the amplitudes and latencies of motion-onset VEPs did not vary with visual acuity. Even for stimuli restricted to the central visual field (5 or 2 deg diameter) or to the peripheral field (excluding the central 5 deg), motion-onset responses were indistinguishable through the two eyes, while pattern-reversal responses always differed significantly in amplitude. These results suggest that the source of motion-onset VEPs (probably an extrastriate motion-sensitive area) is less affected in amblyopia than that of pattern-reversal VEPs (probably the striate cortex). The motion pathway, presumably deriving mainly from the magnocellular layers of the lateral geniculate nucleus, may be relatively spared in amblyopia.

Motion-onset related visual evoked potentials (M-VEPs) were recorded as a result of the three basic (translating, radial and rotating) and one complex (spiral) motion stimulations in five subjects. Low contrast, retinotopically scaled patterns evoked potentials with major motion-onset specific negativity N160 with maximum in the parieto-temporal region. All multidirectional motion stimuli elicited the motion-onset response of significantly higher amplitude and shorter latency compared to the translating (unidirectional) motion. The rotation-onset evoked potentials had significantly shorter latencies than the rest of explored stimuli. The most stable responses with the largest N160 amplitude were recorded to the radial motion. After masking of the central 20 degrees of the visual field these motion-onset VEPs were acquired without statistically significant amplitude drop. The efficiency and usefulness of the radial stimulus is presented in two clinical cases.