Age-Related Amplitude Changes of the Pattern Reversal Evoked Potential Depend on Stimulus Spatial Frequency and Contrast.

摘要

Previous studies which have shown that the amplitude of the PI component of the pattern reversal evoked potential (PREP) is not affected by age may have utilized stimulus configurations which prevented detection of age-related differences. The present study investigated PREP amplitudes in young and older subjects with stimulus and analysis parameters designed to specifically examine NI and PI amplitudes in 10 young and 10 elderly males (mean ages 20 and 64.5 yr). Since a recent report suggests that NI and PI PREP components may reflect cortical activity resulting from the input of distinct visual pathways of the lateral geniculate nucleus, subjects viewed sinusoidal grating stimuli of 0.6 and 6c/deg which phase-reversed every 265 ms. Stimulus contrasts were set at 50% or 6% above threshold contrast. Significantly smaller PI amplitudes for 6c/deg stimulation were found in the elderly for low but not high contrast levels, and older observers had significantly attenuated NI amplitudes for the 6 c/deg-high contrast stimulus. The age-related changes in NI and PI amplitudes were limited to the stimulus spatial frequency, and thus the results do not support a change specific to either magno or parvocellular LGN mechanisms. The results are discussed within the context of recent research on suprathreshold contrast perception.