Hypnosis-induced modulation of corticospinal excitability during motor imagery

Abstract

Hypnosis can be considered an altered state of consciousness in which individuals produce movements under suggestion without apparent voluntary control. Despite its application in contexts implying motor control, evidence for the neurophysiological mechanisms underlying hypnosis is scarce. Inter-individual differences in hypnotic susceptibility suggest that sensorimotor strategies may manifest in a hypnotic state. We tested by means of transcranial magnetic stimulation applied over the primary motor cortex whether motor system activation during a motor imagery task differs in the awake and in the hypnotic state. To capture individual differences, 30 healthy volunteers were classified as high or low hypnotizable (Highs and Lows) according to ad-hoc validated scales measuring hypnotic susceptibility and personality questionnaires. Corticospinal activation during motor imagery in the hypnotic state was greater in the Highs than the Lows. Intrinsic motivation in task performance and level of persuasion modulated corticospinal activation in the Highs. Corticospinal system activation under hypnosis may have practical implications that merit research in areas where hypnosis can be applied to improve motor performance, such as loss of motor abilities and sports.

Physiological Correlates of Hypnotizability: Neural Mechanisms of Hypnosis and Prognostic Role in Medicine

“…2 reduced grey matter volume (GMV) in the insula (Fig. 1A), larger GMV in the mid-temporal and mid-occipital cortices, stronger functional connectivity between the anterior cingulate and the prefrontal dorsolateral cortex (Landry et al, 2017), stronger functional equivalence (FE) between imagined and actual perception/action (Ibanez-Marcelo et al, 2019; Cesari et al 2020), higher excitability of the right motor area in resting conditions (Spina et al, 2020) and of both sides motor areas during motor imagery (Spina et al, 2020;Cesari et al, 2020). Cerebellar morpho-functional differences have also been reported (Fig.…”

“…The reduced grey matter volume in the cerebellar lobules IV-V could be responsible for the highs' less close postural and visuomotor control and absence of learning across successive trials of postural and visuomotor tasks with respect to lows (Santarcangelo and Scattina, 2016). Moreover, reduced inhibition from these lobules on to left motor areas can be responsible for the greater excitability of the highs' right motor cortex, which accounts for their lower motor threshold in the left (Spina et al, 2020) but not right hand (Cesari et al, 2020) in resting conditions. The highs' higher excitability of both sides motor areas observed during motor imagery could be an effect of their stronger functional equivalence between the imagined and actual sensorimotor context.…”

“…Hypnotizability has a few correlates -brain morpho-functional differences (Landry et al, 2017; Picerni et al, 2019), functional equivalence between imagery and perception/action (Ibanez-Marcelo et al, 2019), excitability of the motor cortex (Spina et al, 2020; Cesari et al, 2020), vascular peripheral (Jambrik et al, 2004(Jambrik et al, , 2005 and cerebral control of blood flow (Rashid et al, 2022a,b) -which can be observed out of hypnosis and in the absence of specific suggestions. These correlates can be relevant to hypnotic behaviour and can be useful to prognosis and therapy in a few medical conditions.…”

Physiological Correlates of Hypnotizability: Hypnotic Behaviour and Prognostic Role in Medicine

“…Hypnotizability-related physiological correlates are physiological differences associated with different levels of hypnotizability which can be observed in the ordinary state of consciousness and in the absence of suggestions. Amongst others, differences have been found in brain morpho-functional characteristics [12,13], in the functional equivalence between imagery and perception/action, within groups topological homogeneity and modes of information processing [14], excitability of the motor cortex [15,16], vascular peripheral [17,18] and cerebral control of blood flow [19,20], postural and visuomotor control [21,22], interoception [23][24][25], and polymorphism of µ1 receptors [26].…”

Is hypnotic assessment relevant to neurology?

“…In this scoping review, we propose that hypnotic assessment can assist in the prognosis and treatment of a few neurological diseases. With respect to lows and medium hypnotizables (mediums), in fact, highs display stronger functional equivalence between imagery and perception/ action (FE) and different modes of cortical information processing [11,12], greater excitability of the motor cortex during resting and sensori-motor imagery conditions [13,14], greater proneness to modulate the activity of the immune system [15][16][17][18][19][20] and peculiar abilities to control pain through imagery, despite the low efficacy of their opioid system [21,22]. Although highs represent 15% of the entire population [23], mediums often exhibit physiological characteristics intermediate between highs and lows [13,21], thus being able to take partial advantage from suggestions and hypnotic treatments.…”