Brain functional connectivity of hypnosis without target suggestion. An intrinsic hypnosis rs-fMRI study

Abstract

Objective

During hypnosis, significant changes in the BOLD signal associated with the anterior default mode network (DMN) and prefrontal attentional systems have been reported as evidence of dissociation defined since Charcot. However, it remains uncertain whether these changes are mainly attributable to the hypnotic state per se or to the target suggestions used to verify subject's state during neuroimaging studies. The aim of the present study is to evidence the brain in hypnosis, contrasting the common resting state versus neutral hypnosis (hypnosis in the absence of target suggestions).

Methods

Twenty-four healthy right-handed volunteers (age 28.3 y.o., 12 females) rated moderate hypnotic responsiveness underwent resting state fMRI at 3.0 T in two sessions, once in neutral hypnosis and the other in the common resting state. Each subject's functional data were analyzed for low-frequency BOLD signal correlations seed-to-voxel for the whole brain in the first-level analysis, and seed-to-voxel in a second-level analysis to estimate group results using seeds for five resting state networks: the default mode (DMN), the central executive (CEN), the salience (SaN), the dorso-lateral attention (DAN), and the sensorimotor (SMN) networks.

Results

In general, all network maps of the hypnotic condition presented higher connectivity than those of the resting condition. However, only contrasts for the DAN, SaN, and SMN were statistically significant, including correlated out-of-the-network regions.

Conclusion

Parietal and occipital regions displayed increased connectivity across networks, implying dissociation from the frontal cortices. This is the first fMRI intrinsic study of hypnosis without target suggestion.

Keywords:

• Hypnotisability
• subjective report
• neutral hypnosis
• brain functional connectivity
• resting state networks

Acknowledgements

We thankfully acknowledge the imaging resources and support provided by the “Laboratorio Nacional de Imagenología por Resonancia Magnética (LANIREM)” and CONACyT's network of national laboratories and are also grateful to M.Sc. Leopoldo González-Santos and Dr. Erick H. Pasaye for technical support and Drs. Dorothy Pless and Michael C. Jeziorski for their revision of the manuscript.

Statement of interest

None to declare.

Additional information

Funding

We thank the Programa de Doctorado en Ciencias Biomédicas of the Universidad Nacional Autónoma de México (UNAM) for the doctoral fellowship no. 559395 (PGV) supported by the National Council of Science and Technology, Mexico (Consejo Nacional de Ciencia y Tecnología, CONACYT); the PASPA program at DGAPA-UNAM for the sabbatical fellowship (FAB), and CONACyT for the funding received via grant CB167271.