NMDA Receptor Antagonist Effects on Speech-Related Mismatch Negativity and Its Underlying Oscillatory and Source Activity in Healthy Humans.

Whereas in previous research ketamine’s effects on MMN generated by simple acoustic stimuli were numerically but not statistically different for deviant type (i.e., ketamine tended to attenuate tone duration MMN amplitude more than frequency MMN amplitude on visual inspection alone, but this did not reach statistical significance), ketamine impairment of speech MMNs was observed across all deviant types at frontal and less so at temporal recordings.

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