Spatio-temporal correlates of interocular suppression in amblyopia L Lefebvre1, M Simard2, D Saint-Amour1 |
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1Psychology, Université du Québec à Montréal, QC, Canada |
| A growing body of evidence suggests that normal binocular interactions are still present in amblyopic adults. Here we examined the spatio-temporal neural correlates of interocular suppression in 11 amblyopic adults and 12 controls by recording steady-state high-density (64 channels) EEG using a flash suppression paradigm. The degree of suppression was manipulated by changing the contrast of the "flash" stimulus. At the behavioural level, the flash suppression effect was found in both groups when the dominant eye suppresses the non-dominant eye. Interestingly, the reverse suppression effect was also observed such that the amblyopic eye suppressed the response of the dominant eye. At the EEG level, spectral analysis and current source density (CSD) topographies revealed maximal suppressive response over the occipital cortex (Oz) with similar amplitude and time course in both groups. Suppression EEG responses occurred from 200 to 500 ms after the onset of the flash suppressive stimulus and was delayed as a function of contrast. Although more research is need to be conducted, our findings indicate that the mechanisms of interocular flash suppression in amblyopia are not qualitatively abnormal, suggesting the existence of functional binocular interaction in adult amblyopia. |
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