[Recording of visual evoked potentials in infants: characteristics and optimization of the method].

As the capacities for concentration and fixation are limited in infants and young children it is necessary to adapt the method of VEP measurement. An appropriate stimulus presentation is the appearance, disappearance mode with sequentially presented gratings of different spatial frequencies. Variation in the conditions such as fixation, attention or electrode properties, during a recording session affects all cortical responses equally. The duration of VEP examination is shortened by using rapid sequences of stimuli. The purpose of our study was to improve the presentation of the stimuli. We used a small bright monitor (9 x 9 cm) for stimulation; the test distance was 60 cm, and the mean luminance 60 cd/m2. Stimuli were achromatic gratings. These parameters were chosen in order to compare the results of our method with psychophysical measurements, such as preferential looking (PL) with Teller acuity cards. The gratings with increasing spatial frequencies were presented in a sequence of 7 steps. In order to control the influence of artefacts and the variability of the responses summation/subtraction curve of the responses, was displayed simultaneously with the VEP on the control monitor. By increasing the temporal stimulus frequency in steps from 2.5 Hz (transient stimulus) to higher values we got excellent responses from on/off-stimuli at 5 Hz frequency. Thus the signal-to-noise-ratio was improved without alteration of the spatial transfer function which is found when using higher frequencies due to the Brücke-Bartley-effect.(ABSTRACT TRUNCATED AT 250 WORDS)