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Hannah Shoenhard, Chad S. Duncan, Chris Jones, Michael A. Crognale; Normal chromatic VEPs in a case of cerebral dyschromatopsia. Journal of Vision 2012;12(9):50. doi: 10.1167/12.9.50.
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The chromatic visual evoked potential (crVEP) was used to test the integrity of the chromatic pathways in a patient with bilateral damage to the ventral occipitotemporal cortex. The patient participant was a 46 year old female who experienced a vertebral artery tear that ultimately resulted in cerebral infarct in 2005. Her primary symptoms included achromatopsia, prosopagnosia and topographical agnosia. She also exhibits quadrantanopia with sparing of the macular region. We recently administered a battery of standardized color tests that revealed some improvement in color discrimination. However, significant generalized impairment (dyschromatopsia) remains in agreement with her self-report. Contrast response functions were obtained with the crVEP by way of onset/offset presentations of isoluminant sinusoidal gratings modulated along the LM or S axes of color space. Functions were constructed from amplitudes and latencies of the major CII component and compared with those from an aged-matched population with normal trichromacy. Despite occipitotemporal damage and reduced color discrimination, contrast response functions indicate responses well within the normal range. These results suggest that color processing beyond those stages revealed by the CII component of the spatio-chromatic VEP can be selectively damaged in cases of cerebral dyschromatopsia.
Meeting abstract presented at VSS 2012
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