Hypnotic Suggestions: Their Nature and Applicability in Studying Executive Functions

Exekutive Funktionen (EF) sind eine Gruppe von Top-Down-Prozessen, die in neuartigen Situationen eingesetzt werden, um neue Trigger-Response-Assoziationen herzustellen oder vorhandene Handlungsoptionen an neue Situationen anzupassen. Obwohl EF erschöpfend untersucht wurden, bleiben wichtige Fragen offen. Beispiele dafür sind (a) Sind Exekutivfunktionen vollständig trennbar oder beruhen sie auf einem gemeinsamen neurokognitiven System? (b) Was messen verschiedene Versionen der Stroop-Aufgabe, einer der meist-verwendeten Aufgaben zur Prüfung der Inhibitionsfunktion? (c) Muss Inhibition immer Ressourcen-fordernd sein, oder gibt es eine Form der Inhibition, die mühelos implementiert werden kann? Zur Beantwortung dieser Fragen, habe ich neurokognitive Korrelate von EF und ihrer Verbesserung mithilfe posthypnotischer Suggestionen (PHS) und Ereigniskorrelierter Hirnpotentiale (EKP) untersucht. Zusammenfassend ergaben sich folgende Antworten: (a) Psychometrische und EKP-Daten aus den Studien zur Gedächtnisaktualisierung und Inhibition sowie deren Verbesserung anhand PHS zeigten sowohl funktionsspezifische als auch gemeinsame neurokognitive Prozesse der Inhibition und Aktualisierung. (b) Obwohl sowohl die vokale als auch die manuelle Version der Stroop-Aufgabe Inhibitionsfunktionen erfordern, ist die vokale Version Ressourcen-fordernder, da sie mindestens einen zusätzlichen Lokus der Interferenz im Antwort-Produktionsprozess aufweist, der nicht mit PHS beeinflussbar ist und der in der manuellen Version fehlt. (c) Unter Verwendung PHS zur Erhöhung der Präferenzen für kalorienarme Lebensmittel untersuchte ich die Auflösung von Konflikten. Die EKP-Ergebnisse zeigten, dass auch Konflikt-Auflösung, ähnlich wie Inhibition, Ressourcen konsumiert. Insgesamt zeigt dieses Projekt, dass die Verwendung Aufgaben-bezogener PHS in Kombination mit Neuroimaging-Techniken einen fruchtbaren Ansatz für die Untersuchung ungeklärter Fragen über Exekutivfunktionen darstellt.Executive functions (EF) are a group of top-down processes used in novel situations to develop or adapt existing responses to the task at hand. Even though EFs are studied exhaustively, several important questions remain unanswered: (a) Are EFs entirely separated, or do they rely on a common system? (b) What do different versions of the Stroop task measure? (c) Does inhibition always need to be effortful? To address these questions, I investigated neurocognitive correlates of EFs and their enhancements by means of posthypnotic suggestions (PHS) and event-related potentials (ERP). However, before one can use PHSs, it must be elucidated whether and how they affect EFs. Although PHSs are used repeatedly for improving inhibition, it is unclear whether their effects are mediated by bottom-up or top-down processes. By using an updating task, I showed that effects of PHSs can be attributed to top-down processes. Accordingly, a new theory of hypnosis was proposed and empirically tested by modeling hypnotizability scores with structural equation modeling. In short, the simulation-adaption theory suggests that several top-down processes are employed for responding to suggestions. After elucidating the driving mechanism of PHSs is mentally practicing a novel strategy, PHSs were used for addressing the questions regarding EFs. Summarizing (a) the psychometric and ERP results from several studies indicated that different EFs rely on both function-specific and shared neurocognitive processes. (b) Even though different versions of the Stroop task are tapping into inhibition, the vocal compared to the manual version has at least an extra response-production-related locus of interference. (c) Using PHSs for increasing preferences for low-calorie food items, it is shown that resolve is effortful to implement, as indicated by increased P300 amplitudes. Together, this project shows how PHSs, along with neuroimaging techniques, can provide a novel approach for investigating EFs

Cognitive simulation along with neural adaptation explain effects of suggestions: a novel theoretical framework

Hypnosis is an effective intervention with proven efficacy that is employed in clinical settings and for investigating various cognitive processes. Despite their practical success, no consensus exists regarding the mechanisms underlying well-established hypnotic phenomena. Here, we suggest a new framework called the Simulation-Adaptation Theory of Hypnosis (SATH). SATH expands the predictive coding framework by focusing on (a) redundancy elimination in generative models using intrinsically generated prediction errors, (b) adaptation due to amplified or prolonged neural activity, and (c) using internally generated predictions as a venue for learning new associations. The core of our treatise is that simulating proprioceptive, interoceptive, and exteroceptive signals, along with the top-down attenuation of the precision of sensory prediction errors due to neural adaptation, can explain objective and subjective hypnotic phenomena. Based on these postulations, we offer mechanistic explanations for critical categories of direct verbal suggestions, including (1) direct-ideomotor, (2) challenge-ideomotor, (3) perceptual, and (4) cognitive suggestions. Notably, we argue that besides explaining objective responses, SATH accounts for the subjective effects of suggestions, i.e., the change in the sense of agency and reality. Finally, we discuss individual differences in hypnotizability and how SATH accommodates them. We believe that SATH is exhaustive and parsimonious in its scope, can explain a wide range of hypnotic phenomena without contradiction, and provides a host of testable predictions for future research

Beyond imagination: Hypnotic visual hallucination induces greater lateralised brain activity than visual mental imagery

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised neural mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.Fil: Lanfranco, Renzo C.. University of Edinburgh; Reino Unido. Karolinska Huddinge Hospital. Karolinska Institutet; SueciaFil: Rivera Rei, Álvaro. Universidad Adolfo Ibañez; ChileFil: Huepe, David. Universidad Adolfo Ibañez; ChileFil: Ibañez, Agustin Mariano. Universidad Adolfo Ibañez; Chile. Universidad de San Andrés. Departamento de Matemáticas y Ciencias; Argentina. University of California; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Canales Johnson, Andrés. University of Cambridge; Estados Unidos. Universidad Catolica de Maule; Chil