No Association Between Hypnotizability and Basal Ganglia Morphometry

Abstract

Highlights: What are the main findings? Hypnotizability does not display basal ganglia (BG) structural variations. This is at variance with the reported variations in cerebellum and insula. What are the implications of the main findings? BG do not contribute to the insula/cerebellum-related behavioral differences. Negative findings clarify hypnotizability-related physiological mechanisms. Background: Hypnotizability is a psychophysiological trait measured by standardized scales whose scores indicate the proneness to modify perception, memory, and behavior according to specific suggestions, and to experience the hypnotic state. Hypnotizability exhibits physiological and behavioral correlates in the ordinary state of consciousness and brain morphological peculiarities. Among them, a reduced Grey Matter volume (GMV) of the insula and cerebellar lobules IV–VI has been observed in high hypnotizable individuals (highs) compared to low hypnotizables (lows). Theoretically, these structures could cooperate with the basal ganglia (BG) in hypnotizability-related sensorimotor and cognitive–emotional differences. Methods: Since no imaging study has focused on the BG as a function of hypnotizability, the present research investigated the morphometric characteristics of the BG in the highs (N = 12) and lows (N = 37) enrolled in a previous study focused on the cerebellum. Results: The results did not show any significant difference in the GMV of the caudate and pallidum. Conclusions: Thus, the hypnotizability-related behavioral and physiological difference, as well as the responsiveness to hypnotic suggestions associated with the insula and cerebellum variations, are not partially accounted for by BG structural differences.