PLoS One
December 6, 2017
Eric L Garland, Adam W. Hanley, Phillipe R. Goldin et al.
161 citations
A reanalysis of longitudinal data provides evidence for the mindfulness-to-meaning theory, which proposes that mindfulness promotes positive emotion regulation by increasing the ability to notice and savor positive experiences. The findings suggest that mindfulness training enhances positive emotions through this mechanism, supporting the theory's predictions about how mindfulness fosters well-being.
PLoS One
May 4, 2012
Cédric M. Hysek, Linda D. Simmler, V.g. Nicola et al.
158 citations
Taking the antidepressant duloxetine before MDMA (ecstasy) blocks many of the drug's effects. In a controlled experiment with 16 healthy volunteers, duloxetine prevented MDMA from raising blood pressure, heart rate, and norepinephrine levels, and also reduced the subjective drug experience. This happened even though duloxetine increased MDMA concentrations in the blood. Laboratory tests on human cells confirmed that duloxetine stops MDMA from releasing the neurotransmitters serotonin and norepinephrine. These findings indicate that MDMA's psychological effects depend on its ability to release both serotonin and norepinephrine, and suggest duloxetine could help treat dependence on stimulant drugs.
PLoS One
June 14, 2016
Bryan L. Roth, Simon Gibbons, Warunya Arunotayanun et al.
153 citations
Novel ketamine and phencyclidine analogues sold as designer drugs bind with high affinity to the same NMDA receptor site as the parent compounds, based on radioligand binding assays conducted through a national screening program. Methoxetamine and 3-MeO-PCE, along with the 3- and 4-methoxy analogues of phencyclidine, all showed strong affinity for the PCP-site on the glutamate NMDA receptor. Methoxetamine and phencyclidine and its analogues also bound appreciably to the serotonin transporter, while the PCP analogues had high affinity for sigma receptors. NMDA receptor antagonism likely explains their dissociative and psychotomimetic effects in humans; additional receptor actions may contribute to side effects.
PLoS One
March 27, 2013
Marie Thonnard, Vanessa Charland-Verville, Serge Brédart et al.
140 citations
Near-Death Experiences (NDEs) are not well explained. Because NDEs are sometimes considered imagined, researchers compared the phenomenological characteristics of NDE memories with memories of real and imagined events. Coma survivors with NDEs (8), with coma memories but no NDE (6), and without coma memories (7), plus 18 healthy volunteers, completed the Memory Characteristics Questionnaire. NDE memories had more characteristics than memories of imagined or real events, and more self-referential and emotional information and better clarity than coma memories. These findings suggest NDE memories cannot be considered imagined events; they may be perceived as real despite not being lived in physical reality.
PLoS One
October 31, 2017
Simon B. Goldberg, Raymond P. Tucker, Preston A. Greene et al.
134 citations
A systematic review of 142 randomized clinical trials of mindfulness-based interventions for clinical disorders, published between 2000 and 2016, found no statistically significant increases in six key methodological quality indicators over that period, though changes generally trended toward improvement. When analyses were restricted to studies from Europe and North America, a significant increase in reporting of intent-to-treat analyses emerged. Excluding one early high-quality study revealed improvements in sample size, treatment fidelity assessment, and intent-to-treat reporting. Overall, the findings indicate only modest adoption of recommended methodological improvements across the field.
PLoS One
February 14, 2018
Héléna Cassol, Benoît Pétré, Sophie Degrange et al.
131 citations
Near-death experiences (NDEs) are profound psychological events that can significantly affect experiencers' lives. Previous research shows NDE memories are phenomenologically rich. This study analyzed the narratives of 34 cardiac arrest survivors to extract common themes. A qualitative thematic analysis identified 10 'time-bounded' themes—isolated events during the NDE—and 1 'transversal' theme that characterizes the entire narrative, often as a retrospective self-reflective comment. The division into themes provides detailed vocabulary used by experiencers and enables a rigorous description of the phenomenon, ensuring all self-reported manifestations are included.
PLoS One
March 17, 2021
Marcel O Bonn-Miller, Sue Sisley, Paula Riggs et al.
129 citations
A randomized placebo-controlled trial tested three concentrations of smoked cannabis (high THC, high CBD, THC+CBD) against placebo in military veterans with PTSD. Over three weeks, all groups including placebo showed significant improvements in PTSD symptom severity, but none of the active cannabis concentrations outperformed placebo statistically. The treatments were generally well tolerated. This preliminary trial did not find evidence that smoked cannabis is more effective than placebo for PTSD symptoms in the short term, highlighting the need for further well-powered studies.
PLoS One
May 22, 2013
Adrienne A. Taren, J. David Creswell, Peter J. Gianaros
127 citations
Higher levels of dispositional mindfulness—a trait reflecting present-moment attention and awareness—are associated with smaller grey matter volume in the right amygdala and left caudate in healthy adults. These associations remained after accounting for age, total grey matter volume, neuroticism, and depression. The findings suggest that structural differences in these brain regions may underlie the reduced stress reactivity observed in mindful individuals, pointing to candidate neurobiological pathways linking mindfulness with mental and physical health.
PLoS One
August 28, 2013
Fabio Ferrarelli, Richard Smith, Daniela Dentico et al.
125 citations
Long-term Buddhist meditators with about 8,700 mean lifetime hours of practice show increased gamma power (25-40 Hz) in parietal-occipital regions during non-rapid eye movement sleep compared to meditation-naive individuals. This increase is specific to gamma frequencies, unrelated to spontaneous arousal levels during NREM sleep, and positively correlated with the length of lifetime daily meditation practice. The findings indicate that meditation practice produces measurable changes in spontaneous brain activity and suggest that EEG gamma activity during sleep may serve as a sensitive marker of long-lasting plastic effects of meditative training on brain function.
PLoS One
November 7, 2018
Cassandra Vieten, Helané Wahbeh, B Rael Cahn et al.
124 citations
A survey of 1120 meditators found that most report having had anomalous and extraordinary experiences during meditation, such as mystical, transpersonal, or difficult phenomena. While meditation research has largely focused on clinical effectiveness and neural correlates, these less-studied experiences may be crucial for psychological and spiritual development, act as mediators of meditation's benefits, or be important outcomes themselves. A task force of researchers and teachers developed recommendations to expand research into these areas, which represent largely uncharted scientific terrain suitable for rigorous investigation.
PLoS One
July 10, 2012
Janelle H. P. van Wel, Kim P. C. Kuypers, Eef L. Theunissen et al.
121 citations
MDMA increases both positive moods (vigor, arousal, friendliness, elation) and negative moods (anxiety, confusion) while also slowing reaction times on impulsivity tasks, indicating greater impulse control. Blocking 5-HT(2) receptors with ketanserin prevented the positive mood effects but not the negative mood or impulsivity changes. Blocking 5-HT(1) receptors with pindolol had no effect on any MDMA-related mood or impulse measures. Thus, 5-HT(2) receptors are specifically involved in MDMA's positive mood enhancement, while 5-HT(1) receptors do not appear to play a role in these effects.
PLoS One
January 9, 2017
Pierre Bourdin, Itxaso Barberia, Ramon Oliva et al.
120 citations
An out-of-body illusion induced by virtual reality reduced fear of death compared to a control condition where the illusion was weaker. Sixteen women per group experienced a virtual body from a first-person perspective with synchronized touch and movement, then viewed it from above. In the experimental group, the connection to the virtual body was cut, producing a stronger feeling of disownership; in the control group, synchrony continued. The experimental group reported lower fear of death, consistent with reports that naturally occurring out-of-body experiences are often linked to greater belief in life after death.
PLoS One
September 30, 2015
Eduardo Ekman Schenberg, João Felipe Morel Alexandre, Renato Filev et al.
115 citations
Ayahuasca, an Amazonian plant-based brew used ritually in Brazil and increasingly worldwide, produces a two-phase brain effect. Electroencephalogram recordings and blood measurements of the brew's compounds (DMT, harmine, harmaline, tetrahydroharmine, and their metabolites) showed that 50 minutes after ingestion, alpha brainwave power (8–13 Hz) decreased, mostly in the left parieto-occipital cortex. Between 75 and 125 minutes, slow- and fast-gamma power (30–50 and 50–100 Hz, respectively) increased across multiple cortical regions, including left centro-parieto-occipital, left fronto-temporal, and right frontal areas. These brain changes were significantly linked to circulating levels of ayahuasca's active chemicals. The authors interpret these effects within cognitive and emotional frameworks relevant to ritual use and potential therapeutic applications.
PLoS One
June 30, 2014
Enrico Amico, Francisco Gómez, Carol di Perri et al.
115 citations
Functional connectivity of brain areas fluctuates over time, even during anesthesia. By applying point process analysis to resting-state fMRI data from 18 healthy subjects during propofol-induced wakefulness, sedation, unconsciousness, and recovery, the study identified eight distinct co-activation patterns centered on the posterior cingulate cortex (PCC). The core of these patterns remained stable across consciousness levels, but propofol caused region-specific reductions in co-activation, including disconnections of the prefrontal cortex, thalamus, auditory cortex, motor cortex, and visual area. The methodology helps refine characterization of local functional brain changes associated with propofol-induced modulation of consciousness.
PLoS One
February 4, 2013
Xiancang Ma, Yonghui Dang, Min Jia et al.
115 citations
A single dose of the NMDA receptor antagonist ketamine, but not the GSK-3 inhibitor SB216763, produced long-lasting antidepressant effects in a mouse model of chronic mild stress (CMS). In CMS mice, ketamine reversed the drop in sucrose intake and reduced immobility in the tail suspension and forced swimming tests, effects that persisted for 8 days after a single dose. The GSK-3 inhibitor did not produce these effects. Ketamine also reduced immobility in non-stressed control mice. These results suggest that ketamine's rapid and sustained antidepressant action may not depend on GSK-3 inhibition.
PLoS One
February 10, 2023
Lucia Melloni, Liad Mudrik, Michael Pitts et al.
106 citations
An adversarial collaboration between proponents of Global Neuronal Workspace and Integrated Information Theory devised and preregistered two experiments that test contrasting predictions about the location and timing of correlates of visual consciousness. Six theory-impartial laboratories will follow the study protocol using fMRI, M-EEG, and intracranial EEG, with built-in replications between labs and within datasets. The project aims to provide decisive evidence for or against the two theories and clarify the neural footprints of conscious visual perception, while modeling large-scale, collaborative, and open science practice.
PLoS One
April 26, 2016
Kirk Warren Brown, Robert J. Goodman, Richard M. Ryan et al.
105 citations
Mindful attention, a receptive focus on present-moment experience, improves episodic memory—a key form of long-term memory. A three-study series using the Remember-Know paradigm and free recall found that self-reported mindful attention predicted better recognition memory (Study 1, 143 participants). Very brief focused-attention mindfulness training enhanced recognition memory compared to an active control (Study 2, 93 participants) and generalized to free recall (Study 3, 57 participants). The effect was mediated by intrinsic motivation. These results suggest mindfulness can benefit motivation and episodic memory, with implications for education and work performance.
PLoS One
June 12, 2013
Philip R. Corlett, Victoria C. Cambridge, Jennifer M. Gardner et al.
104 citations
Delusions, the persistent bizarre beliefs characteristic of psychosis, may arise from disturbances in prediction error-dependent learning. In a placebo-controlled study with 18 human subjects, ketamine—an NMDA receptor antagonist that induces aberrant prediction error signals—was administered during re-exposure to a conditioned fear stimulus. This led to stronger subsequent fear memory compared to placebo, with the degree of strengthening correlating with individual vulnerability to ketamine's psychotogenic effects and with prediction error brain signals. A partial replication in an independent sample with an appetitive learning procedure (8 subjects) supported these findings. The results suggest a link between altered prediction error, memory strength, and psychosis, potentially explaining both the emergence and persistence of delusional beliefs.
PLoS One
January 1, 2014
Donal G. Maccoon, Katherine A Maclean, Richard J. Davidson et al.
97 citations
Eight weeks of mindfulness-based stress reduction (MBSR) training did not improve sustained attention more than an active control program (Health Enhancement Program, HEP) in a randomized trial with 63 community participants. The study used a visual continuous performance task to measure attention. Although the main hypotheses were not confirmed, some evidence suggested improved visual discrimination similar to effects seen in other research. Attentional sensitivity was not affected by MBSR, and it remains unclear whether mindfulness might positively affect vigilance. The results highlight procedural modifications needed for future research on sustained attention in similar samples.
PLoS One
April 6, 2012
Jonathan Smallwood, Kevin Brown, Benjamin Baird et al.
92 citations
People vary in how often they have thoughts unrelated to the task at hand, and this variation is linked to longer reaction times when a target appears while baseline pupil diameter is elevated. Because increased baseline pupil diameter can indicate higher tonic activity in the norepinephrine system, the findings suggest that high tonic norepinephrine activity may facilitate task-unrelated thoughts. The authors hypothesize that a high tonic mode of norepinephrine broadly reduces the amplification of task-relevant information, thereby prioritizing internally generated thoughts and shielding them from potentially disruptive external events.
PLoS One
June 27, 2014
Kim P. C. Kuypers, Rafael de la Torre, Magı́ Farré et al.
88 citations
A single 75 mg dose of MDMA selectively enhances emotional empathy—the ability to share and understand others' feelings—without affecting cognitive empathy (understanding others' mental states), trust, or reciprocity in social interactions. This effect was not altered by adding pindolol, a drug that blocks the 5-HT1A serotonin receptor. Oxytocin nasal spray, a hormone often linked to social bonding, had no effect on any empathy or social interaction measure. Changes in emotional empathy were unrelated to oxytocin levels in the blood. The findings suggest that MDMA's empathy-enhancing effects do not depend on peripheral oxytocin and may instead involve other receptors such as serotonin 2A or vasopressin 1A.
PLoS One
November 23, 2020
Nadine Farnes, Bjørn E. Juel, André S. Nilsen et al.
81 citations
In humans, the psychedelic state induced by ketamine is associated with increased diversity and complexity of spontaneous electroencephalography (EEG) signals, but not of evoked EEG responses. This suggests that ketamine's effects on brain dynamics are specific to ongoing, internally generated neural activity rather than to stimulus-driven responses. The finding points to a potential neural marker of altered consciousness under psychedelics.
PLoS One
February 21, 2020
Bheatrix Bienemann, Nina Stamato Ruschel, Maria Luiza Pesse Campos et al.
81 citations
Psilocybin, found in psilocybe mushrooms, has low toxicity and addiction risk, but negative outcomes from its use are not well understood. Analyzing 346 self-reports from an online platform using textual analysis software, the study identified four main clusters: thinking distortions, emergencies, perceptual alterations, and substance administration. Bad trips were more frequent among female users and linked to thinking distortions. Using multiple doses in one session or combining psilocybin with other substances was associated with long-term negative outcomes, while single high doses of mushrooms were linked to medical emergencies. These findings can inform harm-reduction efforts.
PLoS One
November 20, 2009
Stéphane Doly, Jesus Bertran‐gonzalez, Jacques Callebert et al.
80 citations
The drug MDMA (ecstasy) produces its rewarding effects by causing the release of serotonin and dopamine in brain regions linked to reward. This study shows that the 5-HT(2B) receptor, a type of serotonin receptor, is essential for MDMA's reinforcing properties. Mice lacking the 5-HT(2B) receptor did not develop a preference for the location where they received MDMA (10 mg/kg) nor did they show behavioral sensitization. Blocking this receptor with an antagonist also prevented these effects in normal mice. However, at a higher dose (30 mg/kg), MDMA's effects were independent of serotonin and the 5-HT(2B) receptor, relying instead on dopamine. These findings highlight the dose-dependent role of serotonin-dopamine interactions in MDMA's addictive potential.
PLoS One
May 23, 2013
Pawel Z. Kosentka, Sarah L. Sprague, Martin Ryberg et al.
79 citations
Mushroom-forming fungi produce many toxic alkaloids, but the evolution of muscarine (a toxin that stimulates the parasympathetic nervous system) and psilocybin (a hallucinogen) had not been studied. This review and new chemical assays of 30 Inocybaceae samples, including tropical and southern-hemisphere species, tested whether muscarine is ancestral in the family. The results show muscarine evolved independently multiple times, with several losses, and is not ancestral for the whole family. It is a shared derived trait for a clade containing three major lineages (Inocybe, Nothocybe, Pseudosperma) whose common ancestor lived about 60 million years ago. Transitions from muscarine-producing ancestors to psilocybin occurred more recently, 10–20 million years ago, after muscarine loss in two separate lineages. Statistical analyses reject a single origin of muscarine-producing taxa.