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Recent studies have begun to understand sleep not only as a whole-brain process but also as a complex local phenomenon controlled by specific neurotransmitters that act in different neural networks, which is called “local sleep”.... more
Recent studies have begun to understand sleep not only as a whole-brain process but also as a complex local phenomenon controlled by specific neurotransmitters that act in different neural networks, which is called “local sleep”. Moreover, the basic states of human consciousness—wakefulness, sleep onset (N1), light sleep (N2), deep sleep (N3), and rapid eye movement (REM) sleep—can concurrently appear, which may result in different sleep-related dissociative states. In this article, we classify these sleep-related dissociative states into physiological, pathological, and altered states of consciousness. Physiological states are daydreaming, lucid dreaming, and false awakenings. Pathological states include sleep paralysis, sleepwalking, and REM sleep behavior disorder. Altered states are hypnosis, anesthesia, and psychedelics. We review the neurophysiology and phenomenology of these sleep-related dissociative states of consciousness and update them with recent studies. We conclude th...
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Supplemental material, sj-docx-1-jop-10.1177_02698811211069113 for LSD and creativity: Increased novelty and symbolic thinking, decreased utility and convergent thinking by Isabel Wießner, Marcelo Falchi, Lucas Oliveira Maia, Dimitri... more
Supplemental material, sj-docx-1-jop-10.1177_02698811211069113 for LSD and creativity: Increased novelty and symbolic thinking, decreased utility and convergent thinking by Isabel Wießner, Marcelo Falchi, Lucas Oliveira Maia, Dimitri Daldegan-Bueno, Fernanda Palhano-Fontes, Natasha L Mason, Johannes G Ramaekers, Madeleine E Gross, Jonathan W Schooler, Amanda Feilding, Sidarta Ribeiro, Draulio B Araujo and Luís Fernando Tófoli in Journal of Psychopharmacology
Supplemental material, sj-docx-1-jop-10.1177_02698811211069113 for LSD and creativity: Increased novelty and symbolic thinking, decreased utility and convergent thinking by Isabel Wießner, Marcelo Falchi, Lucas Oliveira Maia, Dimitri... more
Supplemental material, sj-docx-1-jop-10.1177_02698811211069113 for LSD and creativity: Increased novelty and symbolic thinking, decreased utility and convergent thinking by Isabel Wießner, Marcelo Falchi, Lucas Oliveira Maia, Dimitri Daldegan-Bueno, Fernanda Palhano-Fontes, Natasha L Mason, Johannes G Ramaekers, Madeleine E Gross, Jonathan W Schooler, Amanda Feilding, Sidarta Ribeiro, Draulio B Araujo and Luís Fernando Tófoli in Journal of Psychopharmacology
Background: Controversy surrounds psychedelics and their potential to boost creativity. To date, psychedelic studies lack a uniform conceptualization of creativity and methodologically rigorous designs. Aims: This study aimed at... more
Background: Controversy surrounds psychedelics and their potential to boost creativity. To date, psychedelic studies lack a uniform conceptualization of creativity and methodologically rigorous designs. Aims: This study aimed at addressing previous issues by examining the effects of lysergic acid diethylamide (LSD) on creativity using multimodal tasks and multidimensional approaches. Methods: In a randomized, double-blind, placebo-controlled, crossover study, 24 healthy volunteers received 50 μg of LSD or inactive placebo. Near drug peak, a creativity task battery was applied, including pattern meaning task (PMT), alternate uses task (AUT), picture concept task (PCT), creative metaphors task (MET) and figural creativity task (FIG). Creativity was assessed by scoring creativity criteria (novelty, utility, surprise), calculating divergent thinking (fluency, originality, flexibility, elaboration) and convergent thinking, computing semantic distances (semantic spread, semantic steps) an...
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Psychedelics acutely impair cognitive functions, but these impairments decline with growing experiences with psychedelics and microdoses may even exert opposing effects. Given the recent evidence that psychedelics induce neuroplasticity,... more
Psychedelics acutely impair cognitive functions, but these impairments decline with growing experiences with psychedelics and microdoses may even exert opposing effects. Given the recent evidence that psychedelics induce neuroplasticity, this explorative study aimed at investigating the potential of psychedelics to sub-acutely change cognition. For this, we applied a randomized, double-blind, placebo-controlled, crossover study with 24 healthy volunteers receiving 50 μg lysergic acid diethylamide (LSD) or an inactive placebo. Sub-acute changes in cognition were measured 24 h after dosing, including memory (Rey-Osterrieth Complex Figure, ROCF; 2D Object-Location Memory Task, OLMT; Rey Auditory-Verbal Learning Test, RAVLT), verbal fluency (phonological; semantic; switch), design fluency (basic; filter; switch), cognitive flexibility (Wisconsin Card Sorting Test, WCST), sustained and switching attention (Trail Making Test, TMT), inhibitory control (Stroop Task) and perceptual reasoning (Block Design Test, BDT). The results show that when compared to placebo and corrected for Body Mass Index (BMI) and abstinence period from psychedelics, LSD sub-acutely improved visuospatial memory (ROCF immediate recall points and percentage, OLMT consolidation percentage) and phonological verbal fluency and impaired cognitive flexibility (WCST: fewer categories achieved; more perseveration, errors and conceptual level responses). In conclusion, the low dose of LSD moderately induced both "afterglow" and "hangover". The improvements in visuospatial memory and phonological fluency suggest that LSD-assisted therapy should be explored as a novel treatment perspective in conditions involving memory and language declines such as brain injury, stroke or dementia.
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Background For a century, psychedelics have been investigated as models of psychosis for demonstrating phenomenological similarities with psychotic experiences and as therapeutic models for treating depression, anxiety, and substance use... more
Background For a century, psychedelics have been investigated as models of psychosis for demonstrating phenomenological similarities with psychotic experiences and as therapeutic models for treating depression, anxiety, and substance use disorders. This study sought to explore this paradoxical relationship connecting key parameters of the psychotic experience, psychotherapy, and psychedelic experience. Methods In a randomized, double-blind, placebo-controlled, crossover design, 24 healthy volunteers received 50 μg d-lysergic acid diethylamide (LSD) or inactive placebo. Psychotic experience was assessed by aberrant salience (Aberrant Salience Inventory, ASI), therapeutic potential by suggestibility (Creative Imagination Scale, CIS) and mindfulness (Five Facet Mindfulness Questionnaire, FFMQ; Mindful Attention Awareness Scale, MAAS; Experiences Questionnaire, EQ), and psychedelic experience by four questionnaires (Altered State of Consciousness Questionnaire, ASC; Mystical Experiences...
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We know that stochastic feedback impairs children’s associative stimulus-response (S-R) learning (Crone, Jennigs, & Van der Molen, 2004a; Eppinger, Mock, & Kray, 2009), but the impact of stochastic feedback on sequence learning that... more
We know that stochastic feedback impairs children’s associative stimulus-response (S-R) learning (Crone, Jennigs, & Van der Molen, 2004a; Eppinger, Mock, & Kray, 2009), but the impact of stochastic feedback on sequence learning that involves deductive reasoning has not been not tested so far. In the current study, 8- to 11-year-old children (N = 171) learned a sequence of four left and right button presses, LLRR, RRLL, LRLR, RLRL, LRRL and RLLR, that needed to be deduced from feedback because no directional cues were given. One group of children experienced consistent feedback only (deterministic feedback, 100% correct). In this condition, green feedback on the screen indicated that the children had been right when they were right, and red feedback indicated that the children had been wrong when they were wrong. Another group of children experienced inconsistent feedback (stochastic feedback, 85% correct, 15% false), where in some trials, green feedback on the screen could signal that children were right when in fact they were wrong, and red feedback could indicate that they were wrong when in fact they had been right. Independently of age, children’s sequence learning in the stochastic condition was initially much lower than in the deterministic condition, but increased gradually and improved with practice. Responses towards positive vs. negative feedback varied with age. Children were increasingly able to understand that they could have been wrong when feedback indicated they were right (self-reflection), but they remained unable to understand that they could have been right when feedback indicated they were wrong (self-assertion).
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Introduction: Gamma oscillations in the primary somatosensory cortex (SI) are involved in the coding of pain intensity. Whereas hypnotic analgesia might reduce subjective pain intensity, the brain mechanisms that underlie hypnotic... more
Introduction: Gamma oscillations in the primary somatosensory cortex (SI) are involved in the coding of pain intensity. Whereas hypnotic analgesia might reduce subjective pain intensity, the brain mechanisms that underlie hypnotic analgesia remain unclear and the role of gamma oscillations has hardly been investigated.
Method: Painful and non-painful electrical stimuli were delivered to 19 high suggestible subjects in a within subject design with a hypnotic analgesia condition (hypnosis) and a non-hypnotic control condition (control). Subjective stimulus intensity was measured, as well as electroencephalographic (EEG) gamma power (30–120 Hz) at the contralateral electrode C4.
Results: Painful stimuli were rated as less intensive under hypnosis compared to the control. Gamma power was higher for painful than for non-painful stimuli in the control. As for painful stimuli gamma power was reduced in hypnosis compared to the control.
Conclusions: The coding mechanisms of stimulus intensity seems to remain largely unchanged under hypnotic analgesia, wereas subjective pain reduction is related to gamma modulations that have to be seen in a spatially and temporally more global context. The results appear to be in line with a frontally controlled breakdown in neuronal communication under hypnotic analgesia as postulated by Miltner and Weiss (2007).
Method: Painful and non-painful electrical stimuli were delivered to 19 high suggestible subjects in a within subject design with a hypnotic analgesia condition (hypnosis) and a non-hypnotic control condition (control). Subjective stimulus intensity was measured, as well as electroencephalographic (EEG) gamma power (30–120 Hz) at the contralateral electrode C4.
Results: Painful stimuli were rated as less intensive under hypnosis compared to the control. Gamma power was higher for painful than for non-painful stimuli in the control. As for painful stimuli gamma power was reduced in hypnosis compared to the control.
Conclusions: The coding mechanisms of stimulus intensity seems to remain largely unchanged under hypnotic analgesia, wereas subjective pain reduction is related to gamma modulations that have to be seen in a spatially and temporally more global context. The results appear to be in line with a frontally controlled breakdown in neuronal communication under hypnotic analgesia as postulated by Miltner and Weiss (2007).
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Background: Learning and memory are improved by night sleep. Whereas non REM (NREM) sleep rather improves declarative memory, REM sleep rather improves procedural memory. And even a short midday nap and deep relaxation can improve memory... more
Background: Learning and memory are improved by night sleep. Whereas non REM (NREM) sleep rather improves declarative memory, REM sleep rather improves procedural memory. And even a short midday nap and deep relaxation can improve memory performance. But as a midday nap contains less REM phases than night sleep, it is questionable whether it improves procedural memory, too.
Methods: In the present magnetoencephalography (MEG) study, we compared the effects of a short midday nap, compared to deep relaxation, on different memory types and oscillatory activity in a between subject design. We used the Rey-Osterrieth complex figure (ROCF) to test declarative memory performance and a mirror drawing task to test the procedural memory.
Results: There were no differences in performance between the sleep and deep relaxation group. However, the sleep group showed higher theta (6–9 Hz) activity than the deep relaxation group during both tasks. Increased theta activity is associated with better performance in memory retrieval. We found no overall relation between theta and mirror drawing task performance (procedural memory). However, there was a positive correlation of theta activity and ROCF task performance (declarative memory) on a trend significance level.
Conclusions: As the sleep group showed higher theta activity during ROCF task performance and theta activity correlated positively with ROCF task performance, we conclude that theta oscillations are important for declarative memory and that sleep, compared to deep relaxation, improves (declarative) memory retrieval. We were not able to show this for procedural memory. We assume that the lack of significant results regarding performance improvement, group difference and correlations were due to the small sample (N=9).
Significance: To our knowledge, this was the first MEG study to investigate the effects of sleep and deep relaxation on memory. Future studies might confirm our preliminary results.
Methods: In the present magnetoencephalography (MEG) study, we compared the effects of a short midday nap, compared to deep relaxation, on different memory types and oscillatory activity in a between subject design. We used the Rey-Osterrieth complex figure (ROCF) to test declarative memory performance and a mirror drawing task to test the procedural memory.
Results: There were no differences in performance between the sleep and deep relaxation group. However, the sleep group showed higher theta (6–9 Hz) activity than the deep relaxation group during both tasks. Increased theta activity is associated with better performance in memory retrieval. We found no overall relation between theta and mirror drawing task performance (procedural memory). However, there was a positive correlation of theta activity and ROCF task performance (declarative memory) on a trend significance level.
Conclusions: As the sleep group showed higher theta activity during ROCF task performance and theta activity correlated positively with ROCF task performance, we conclude that theta oscillations are important for declarative memory and that sleep, compared to deep relaxation, improves (declarative) memory retrieval. We were not able to show this for procedural memory. We assume that the lack of significant results regarding performance improvement, group difference and correlations were due to the small sample (N=9).
Significance: To our knowledge, this was the first MEG study to investigate the effects of sleep and deep relaxation on memory. Future studies might confirm our preliminary results.