Monocular viewing during early infancy reveals asymmetries in optokinetic n
ystagmus (OKN) and visual evoked potentials (VEPs). This study investigates
the VEP asymmetry to see if it is consistent in direction with the OKN asy
mmetry. Steady-state VEPs were recorded from infants (5-21 weeks) viewing g
ratings that underwent successive displacements in the same direction, left
ward or rightward. In addition, transient VEPs were recorded to the two dir
ections of an oscillating stimulus. Both tests produced larger VEP amplitud
es for nasal-to-temporal compared to temporal-to-nasal movement. Horizontal
eye movements were monitored by EOG while viewing these stimuli to test wh
ether the asymmetry was a consequence of eye movements. No difference in ev
e movements as a function of the stimulus was found. excluding differences
in retinal slip as an explanation of the asymmetry. The stronger neural res
ponse for nasal-to-temporal displacements is opposite to the asymmetry of O
KN. Oculomotor and VEP asymmetries may be related: however this relationshi
p is not simply that the stronger neural response, indicated by the VEP, le
ads to a stronger optokinetic response. (C) 2001 Elsevier Science Ltd. All
rights reserved.