Abstract
When stimulated with visual “white noise” stimuli, individuals typically show a characteristic evoked response in the alpha frequency range (8-14 Hz) of the electroencephalogram (EEG). This phenomenon has been hypothesized to indicate the underlying frequency of the visual system. However, the relationship between endogenous and stimulus-evoked alpha oscillations is debated. Endogenous alpha activity is known to crucially depend on patterned visual experience after birth. In order to test whether the same is true of evoked alpha activity, we compared individuals who had received delayed surgery for dense bilateral congenital cataracts (n = 13, Mean duration of visual deprivation = 11.0 (SD = 8.9) years) to typically sighted individuals matched for age (n = 13) on an EEG paradigm adapted from VanRullen and MacDonald (2012). Participants performed a target detection task while observing a central visual stimulus that changed in luminance at frequencies between 0-30 Hz, with equal power at all frequencies. We observed a reduced likelihood of exhibiting an evoked alpha response and an overall decreased amplitude of the evoked alpha response in cataract-reversal individuals compared to sighted individuals. This reduction corresponded with a reduction of the resting state alpha activity in the same cataract-reversal individuals. Together, these findings demonstrate that the development of characteristic alpha activity, both in the evoked response and at rest, requires typical visual input at birth. Further, our results provide empirical evidence from humans in favor of evoked and endogenous visual alpha activity being supported by closely related neural mechanisms and similar developmental trajectories.