Abstract: PURPOSE: It is well known that there are characteristic differences in internal state when eyes are open versus eyes closed in the dark. It is however not clear, how the alternation in the internal state affects stimulus induced plasticity. In this study, we directly address this question by comparing the short-term monocular deprivation-induced ocular dominance plasticity under conditions where the patched eye is either open or closed under the patch.
METHODS: Fourteen normal adults participated in the psychophysical test to access the shift of sensory eye dominance after a 2.5-h of monocular deprivation under conditions where the patched eye is either open or closed under the black occluder. The sensory eye dominance before and after patching was quantified using either the binocular combination and the binocular rivalry tasks. Another eight normal adults participated in the EEG test to assess their amplitudes of alpha oscillation with the two eyes closed, two eyes open, patching with the patched eye open and patching with the patched eye closed.
RESULTS: Previous studies have shown that 2.5-hour of monocular deprivation temporarily strengthens the previously patched eye's contribution to binocular perception. Here, we show that this form of visual plasticity is enhanced if the patched eye behind the occluder is kept open, even though the visual input is unchanged. We document these enhancements using both binocular combination and binocular rivalry endpoint measures. This effect could not be accounted for in terms of the change in the spontaneous alpha power in the eyes open/eyes close condition.
CONCLUSIONS: The alternation in the internal state affects short-term monocular deprivation-induced ocular dominance plasticity, which is quite different with the differences in internal state when the two eyes are open versus eyes closure and suggests a separate neuroplastic mechanism specific to binocular function.