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Erratum

        Erratum to: “Reply to: Deep Brain Stimulation for Depression: Is It a Gray or White “Matter”?” by Clement Hamani and José N. Nobrega (Biol Psychiatry corrected article-in-press, available online Jan 26, 2016). This article is being corrected between the corrected proof and final print version stages of publication. It came to the authors’ attention that the last four sentences of the article needed to be altered to correct a misunderstanding of the prior literature. The original text and corrected text are both provided here for clarity.
        The original text was as follows: “Even at a concentration twice as high as the one in our study, axonal projections from cortical neurons have been shown to be viable 2 months after cell bodies were injured by IBO (9). Thus, it is conceivable that the doses of IBO used in our study may have largely compromised cell bodies without fully affecting axonal projections. We suggest that by using higher doses of IBO, Etiévant et al. may have injured PFC neurons as well as their axons, rendering DBS ineffective. Although this explanation would help to reconcile discrepancies between our studies, it is speculative and would need to be verified in further experiments.”
        The correct text is as follows: “Even at a concentration twice as high as the one in our study, axonal projections to cortical neurons have been shown to be viable 2 months after cell bodies were injured by IBO (9). In the intact brain, axonal projections from PFC principal cells seem to be a key substrate for the antidepressant-like effects of DBS in the forced swim test. In our study, we did not investigate the neural elements responsible for the preserved DBS response following IBO. Whether these consisted of surviving projections from a small number of noninjured cells, afferents to the target, fibers en-passant, or even glia remains to be demonstrated. Given the complexity of DBS mechanisms, it is possible that multiple elements may be recruited and contribute to the antidepressant-like response of this therapy.”

        Linked Article

        • Reply to: Deep Brain Stimulation for Depression: Is It a Gray or White “Matter”?
          Biological PsychiatryVol. 80Issue 6
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            We thank Etiévant et al. (1) for their comments and the opportunity to discuss our data. In response, we should first consider some of the concepts involving deep brain stimulation (DBS) at high frequencies (e.g., >100 Hz). One of the mechanisms commonly described is a depolarization block. This mechanism is characterized by a state in which cells undergo depolarization with an almost complete abolishment of spontaneous action potentials (functional inactivation) (2). In addition, DBS excites fiber pathways in the vicinity of the electrodes (efferent and afferent projections from and to the targeted region as well as fibers en passant) (2,3); this is important, as the anterograde and retrograde propagation of action potentials may influence the functioning of brain regions projecting to or receiving projections from the stimulated site.
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