Hypnotizability influences the cortical representation of visually and kinaesthetically imagined head position.

The study investigates the cortical representation of the visual and kinesthetic image of a rotated position of the head in highly (highs) and low hypnotizable individuals (lows) of both gender. Participants were invited to imagine maintaining their head rotated toward one side by seeing their chin aligned with their right shoulder (V, visual imagery), and in a different condition, by feeling tension in their neck muscles (K, kinaesthetic imagery). Vividness of imagery and cognitive effort were reported after each task. Alpha and beta band absolute power was studied. Highs reported higher vividness than lows only for the kinaesthetic modality of imagery. The cortical desyncronization observed during visual and kinaesthetic imagery were different in high females (HM), low females (LF), high males (HM) and low males (LM). In fact, only HF and LM exhibited significant power changes during the kinaesthetic task, whereas visual imagery was associated with cortical desynchronization in all subgroups except HM. The study supports earlier findings of an advantage of highs in kinesthetic imagery, shows an intriguing interaction of hypnotizability and gender, and indicates topographical difference in the four subgroups of participants suggesting differences in underlying generators.