Taking the body off the mind: Decreased functional connectivity between somatomotor and default-mode networks following Floatation-REST

Hum Brain Mapp. 2021 Jul;42(10):3216-3227. doi: 10.1002/hbm.25429. Epub 2021 Apr 9.

Abstract

Floatation-Reduced Environmental Stimulation Therapy (REST) is a procedure that reduces stimulation of the human nervous system by minimizing sensory signals from visual, auditory, olfactory, gustatory, thermal, tactile, vestibular, gravitational, and proprioceptive channels, in addition to minimizing musculoskeletal movement and speech. Initial research has found that Floatation-REST can elicit short-term reductions in anxiety, depression, and pain, yet little is known about the brain networks impacted by the intervention. This study represents the first functional neuroimaging investigation of Floatation-REST, and we utilized a data-driven exploratory analysis to determine whether the intervention leads to altered patterns of resting-state functional connectivity (rsFC). Healthy participants underwent functional magnetic resonance imaging (fMRI) before and after 90 min of Floatation-REST or a control condition that entailed resting supine in a zero-gravity chair for an equivalent amount of time. Multivariate Distance Matrix Regression (MDMR), a statistically-stringent whole-brain searchlight approach, guided subsequent seed-based connectivity analyses of the resting-state fMRI data. MDMR identified peak clusters of rsFC change between the pre- and post-float fMRI, revealing significant decreases in rsFC both within and between posterior hubs of the default-mode network (DMN) and a large swath of cortical tissue encompassing the primary and secondary somatomotor cortices extending into the posterior insula. The control condition, an active form of REST, showed a similar pattern of reduced rsFC. Thus, reduced stimulation of the nervous system appears to be reflected by reduced rsFC within the brain networks most responsible for creating and mapping our sense of self.

Trial registration: ClinicalTrials.gov NCT02452203.

Keywords: consciousness; default-mode network; fMRI; insula; posterior cingulate; resting-state; self; somatosensory.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Connectome*
  • Default Mode Network / diagnostic imaging
  • Default Mode Network / physiology*
  • Female
  • Humans
  • Hydrotherapy*
  • Insular Cortex / diagnostic imaging
  • Insular Cortex / physiology*
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Motor Cortex / diagnostic imaging
  • Motor Cortex / physiology*
  • Nerve Net / diagnostic imaging
  • Nerve Net / physiology*
  • Sensory Deprivation / physiology*
  • Somatosensory Cortex / diagnostic imaging
  • Somatosensory Cortex / physiology*
  • Young Adult

Associated data

  • ClinicalTrials.gov/NCT02452203