In adults the motion-onset visual evoked potentials (M-VEPs) represent a useful diagnostic tool in neuro-opthalmology (Kuba et al.,Vision Res., 2007, 47, 189-202) since they test quite selectively the magnocellular system/dorsal stream function. Whilst in adults robust M-VEPs with low variability can be acquired easily, it is difficult to record and evaluate them in children. They not only display very long maturation and age dependent shape development (Langrova et al., Vision Res., 2006, 46, 536-544) but in some children they are unidentifiable to standard stimuli.Methods
To understand better this problem we tested 30 normal children aged 7 - 12 years. Two types of motion stimuli were used – translation motion (TM) and expansion/contraction motion (EXCOM).Results
Reliable VEPs were detected in 77% of children to TM and in 83% of children to EXCOM. The dominant peak of the VEPs was negative in all TM VEPs and in 80 % of EXCOM VEPs (positive in 20%). In both VEP variants the latency of the negative peak did not shorten significantly in the tested age range and there was large interindividual latency variability (176 ms – 268 ms). High contrast stimuli (non-optimal “magno” stimulus) shortened the M-VEPs latencies and enlarged amplitudes in majority of subjects. M-VEPs to peripheral stimulation (outside central 20°) were in contrast to adults detectable only in 43 % of children.Conclusion
These findings show distinct differences in maturation of motion perception in children, which makes a diagnostic use of M-VEPs in children quite complicated. Acknowledgement: Supported by the project PRVOUK - P37/07.