Chronic deep brain stimulation of the rat ventral medial prefrontal cortex disrupts hippocampal-prefrontal coherence

Nathan Insel, Maryna Pilkiw, José N. Nobrega, William D. Hutchison, Kaori Takehara-Nishiuchi, Clement Hamani

Research output: Contribution to journalArticlepeer-review

Abstract

Deep brain stimulation (DBS) of the subgenual cingulate gyrus (SCG) has been used to treat patients with treatment-resistant depression. As in humans, DBS applied to the ventromedial prefrontal cortex of rats induces antidepressant-like responses. Physiological interactions between structures that play a role in depression and antidepressant treatment are still unknown. The present study examined the effect of DBS on inter-region communication by measuring the coherence of local field potentials in the rat infralimbic cortex (IL; homologue of the SCG) and one of its major afferents, the ventral hippocampus (VH). Rats received daily IL DBS treatment (100. μA, 90. μs, 130. Hz; 8. h/day). Recordings were conducted in unrestrained, behaving animals on the day before treatment, after 1 and 10. days of treatment, and 10. days stimulation offset. VH-IL coherence in the 2-4. Hz range was reduced in DBS-treated animals compared with shams after 10. days, but not after only 1. day of treatment. No effect of DBS was observed in the 6-10. Hz (theta) range, where coherence was generally high and could be further evoked with a loud auditory stimulus. Finally, coherence was not affected by fluoxetine (10. mg/kg), suggesting that the effects of DBS were not likely mediated by increased serotonin levels. While these data support the hypothesis that DBS disrupts communication between regions important for expectation-based control of emotion, they also suggest that lasting physiological effects require many days of treatment and, furthermore, may be specific to lower-frequency patterns, the nature and scope of which await further investigation.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalExperimental Neurology
Volume269
DOIs
StatePublished - Jul 1 2015

Keywords

  • Delta
  • Depression
  • Functional connectivity
  • Oscillations
  • Synchrony

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