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What does recognition of an object do to its representation in the brain? Previous research demonstrated that recognition alters the spatial patterns of fMRI activation even in early visual cortex (Hsieh et al. 2010). This process is thought to depend on feedback from higher-level areas to early visual areas. In turn, feedback activity is suggested to rely on the NMDA-receptor. To investigate the role of feedback in the effect of recognition, we administered Ketamine, an NMDA-receptor antagonist, or a placebo to participants. Participants viewed Mooney images that were initially unrecognizable and later recognizable and grayscale photo versions of the same images. We used representational dissimilarity matrixes (RDM) to investigate how the spatial patterns of fMRI activation changed with recognition. Preliminary data suggests that when the Mooney images are unrecognizable their representation pattern is more …