doi: 10.1097/ALN.0000000000000244

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Mashour, George A. M.D., Ph.D.; Icaza, Eduardo E. M.D.

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We thank Dr. dos Santos for his interest in our article1 and his scholarly perspective regarding the neurobiology of the psychedelic state. In response to his comments, our focus on the glutamatergic N-methyl-D-aspartate receptor was motivated by the pharmacology of anesthetic drugs that have been more strongly associated with psychedelic experiences in humans; we did not argue that these receptors were the primary molecular targets for psychedelic drugs themselves. In terms of neuroimaging studies, we thank Dr. dos Santos for the additional references and we acknowledge that the article by Carhart-Harris et al.2 is not the only neuroimaging study on the psychedelic state. It would have been more precise for us to state that it is the only neuroimaging study focused on connectivity during the psychedelic state in humans. By contrast, the studies referenced by Dr. dos Santos focused on neural activity. The findings by Carhart-Harris et al. regarding connectivity allowed us to make comparisons with more recent studies on anesthetic-induced unconsciousness. Finally, we agree with Dr. dos Santos that there are many more exciting questions to be addressed in this area of investigation.
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Competing Interests

The authors declare no competing interests.
George A. Mashour, M.D., Ph.D., Eduardo E. Icaza, M.D.
University of Michigan Medical School, Ann Arbor, Michigan (G.A.M.).
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1. Icaza EE, Mashour GA. Altered states: Psychedelics and anesthetics. ANESTHESIOLOGY. 2013;119:1255–60

2. Carhart-Harris RL, Erritzoe D, Williams T, Stone JM, Reed LJ, Colasanti A, Tyacke RJ, Leech R, Malizia AL, Murphy K, Hobden P, Evans J, Feilding A, Wise RG, Nutt DJ. Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proc Natl Acad Sci U S A. 2012;109:2138–43

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