Suggested visual blockade during hypnosis: Top-down modulation of stimulus processing in a visual oddball task

Abstract

Several theories of hypnosis assume that responses to hypnotic suggestions are implemented through top-down modulations via a frontoparietal network that is involved in monitoring and cognitive control. The current study addressed this issue re-analyzing previously published event-related-potentials (ERP) (N1, P2, and P3b amplitudes) and combined it with source reconstruction and connectivity analysis methods. ERP data were obtained from participants engaged in a visual oddball paradigm composed of target, standard, and distractor stimuli during a hypnosis (HYP) and a control (CON) condition. In both conditions, participants were asked to count the rare targets presented on a video screen. During HYP participants received suggestions that a wooden board in front of their eyes would obstruct their view of the screen. The results showed that participants’ counting accuracy was significantly impaired during HYP compared to CON. ERP components in the N1 and P2 window revealed no amplitude differences between CON and HYP at sensor-level. In contrast, P3b amplitudes in response to target stimuli were significantly reduced during HYP compared to CON. Source analysis of the P3b amplitudes in response to targets indicated that HYP was associated with reduced source activities in occipital and parietal brain areas related to stimulus categorization and attention. We further explored how these brain sources interacted by computing time-frequency effective connectivity between electrodes that best represented frontal, parietal, and occipital sources. This analysis revealed reduced directed information flow from parietal attentional to frontal executive sources during processing of target stimuli. These results provide preliminary evidence that hypnotic suggestions of a visual blockade are associated with a disruption of the coupling within the frontoparietal network implicated in top-down control.

Safety on demand: Post‐hypnotic suggestions of safety reduce neural signals of reward sensitivity with long‐term beneficial effects

“…In previous hypnosis studies conducted in our lab, we found significant modulations of electrophysiological brain responses after hypnotic suggestions with an effect size of d = 0.7 (Franz et al, 2020(Franz et al, , 2021Schmidt, Hecht et al, 2017). To detect an effect of at least this size based on an alpha level of α = 0.05 and a power level of 1β = 0.95, a total of 24 participants is required according to G*Power (Faul et al, 2009).…”

Spatiotemporal Dynamics of Covert Attention With Different Degrees of Central Visual Field Defects: An ERP and sLORETA Study

“…There were several stages of attentional processing when simulating visual field defects. 46 , 47 First, information inputs under simulated defect conditions captured attention through initial perceptual processing (indexed by N1) to form preliminary representations in the occipital cortex. Second, the higher prefrontal cortex evaluated visual representations and gave forward feedback to the occipital cortex to reactivate visual representations (indexed by P2).…”

Feeling Safe With Hypnosis: Eliciting Positive Feelings During a Special State of Consciousness

“…The results show the neuronal dissociation between perceiving the visual objects on the screen and attending them in order to count them, reflected in early and late event-related EEG signals. In a subsequent analysis, we found that this effect was driven by a top-down modulation, reflected in reduced directed information flow from parietal attentional to frontal executive sources during processing of target stimuli ( Franz et al, 2021 ).…”

“…In three separate EEG studies, I blocked sensory perception of visual, pain, and auditory stimuli using hypnotic suggestions of a wooden board in front of participants’ eyes, a cooling and numbing glove on participants’ hands and earplugs in participants’ ears, respectively ( Figure 1 ; Schmidt et al, 2017b ; Franz et al, 2020 , 2021 ). We used a sensory paradigm that is very common in EEG research with frequent and rare stimuli, called oddball paradigm.…”