title: Repetitive speech elicits widespread deactivation in the human cortex: the "Mantra" effect?
abstract: BACKGROUND
  Mantra (prolonged repetitive verbal utterance) is one of the most universal mental practices in human culture. However, the underlying neuronal mechanisms that may explain its powerful emotional and cognitive impact are unknown. In order to try to isolate the effect of silent repetitive speech, which is used in most commonly practiced Mantra meditative practices, on brain activity, we studied the neuronal correlates of simple repetitive speech in nonmeditators - that is, silent repetitive speech devoid of the wider context and spiritual orientations of commonly practiced meditation practices.
  
  
  METHODS
  We compared, using blood oxygenated level-dependent (BOLD) functional magnetic resonance imaging (fMRI), a simple task of covertly repeating a single word to resting state activity, in 23 subjects, none of which practiced meditation before.
  
  
  RESULTS
  We demonstrate that the repetitive speech was sufficient to induce a widespread reduction in BOLD signal compared to resting baseline. The reduction was centered mainly on the default mode network, associated with intrinsic, self-related processes. Importantly, contrary to most cognitive tasks, where cortical-reduced activation in one set of networks is typically complemented by positive BOLD activity of similar magnitude in other cortical networks, the repetitive speech practice resulted in unidirectional negative activity without significant concomitant positive BOLD. A subsequent behavioral study showed a significant reduction in intrinsic thought processes during the repetitive speech condition compared to rest.
  
  
  CONCLUSIONS
  Our results are compatible with a global gating model that can exert a widespread induction of negative BOLD in the absence of a corresponding positive activation. The triggering of a global inhibition by the minimally demanding repetitive speech may account for the long-established psychological calming effect associated with commonly practiced Mantra-related meditative practices.
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science 234 Herzl St., Rehovot, 76100, Israel.
authors.forename: Aviva
authors.initials: A
authors.lastname: Berkovich-Ohana
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science 234 Herzl St., Rehovot, 76100, Israel.
authors.forename: Meytal
authors.initials: M
authors.lastname: Wilf
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science 234 Herzl St., Rehovot, 76100, Israel.
authors.forename: Roni
authors.initials: R
authors.lastname: Kahana
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science 234 Herzl St., Rehovot, 76100, Israel.
authors.forename: Amos
authors.initials: A
authors.lastname: Arieli
authors.affiliation: Department of Neurobiology, Weizmann Institute of Science 234 Herzl St., Rehovot, 76100, Israel.
authors.forename: Rafael
authors.initials: R
authors.lastname: Malach
mesh_terms: D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D010100:Oxygen / Q000097:blood; D012146:Rest; D013060:Speech / Q000502:physiology*; D013239:Stereotyped Behavior / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: Default mode network; fMRI; global inhibition; mantra; meditation