Scientific Reports
April 19, 2017
Michael Schartner, Robin Carhart-Harris, Adam B. Barrett et al.
450 citations
Measures of neural signal diversity, such as entropy and Lempel-Ziv complexity, are higher during wakeful rest than during anesthesia. In this study, these measures were computed for spontaneous magnetoencephalographic signals from humans under psilocybin, ketamine, and LSD. All three psychedelics produced reliably higher signal diversity, even after controlling for spectral changes, with the most pronounced increase in temporal (single-channel LZ complexity) rather than spatial diversity. Selective correlations emerged between changes in signal diversity and the intensity of psychedelic experience. This is the first time these measures have been applied to the psychedelic state and have yielded values exceeding normal waking consciousness, suggesting that psychedelic phenomenology constitutes an elevated level of consciousness.
Scientific Reports
February 10, 2020
Frederick S. Barrett, Manoj K. Doss, Nathan D. Sepeda et al.
375 citations
A single 25 mg/70 kg dose of psilocybin temporarily reduced negative affect and amygdala response to negative facial expressions one week later in twelve healthy volunteers, while positive affect and prefrontal cortex responses to emotional conflict increased. One month later, negative affect and amygdala reactivity returned to baseline, but positive affect remained elevated and trait anxiety was lower. The number of resting-state functional connections across the brain increased from baseline to both one week and one month after dosing. These preliminary findings suggest psilocybin may enhance emotional and brain plasticity, with negative affect as a potential therapeutic target.
Scientific Reports
November 23, 2021
Christopher Timmermann, Hannes Kettner, Chris Letheby et al.
208 citations
People who use psychedelic drugs often shift away from materialist views of reality and consciousness toward panpsychism and fatalism, with most changes lasting at least six months. In a large prospective online survey, these belief shifts correlated with greater past psychedelic use and improved mental health. Emotional synchrony with others during the experience mediated the changes, and baseline impressionability moderated them. An independent clinical trial confirmed the direction of belief change, suggesting psychedelics may causally influence metaphysical beliefs away from hard materialism, though contextual independence remains uncertain.
Scientific Reports
October 25, 2017
Liila Taruffi, Corinna Pehrs, Stavros Skouras et al.
177 citations
Listening to sad music, compared with happy music, leads people to withdraw attention inward and engage in more mind-wandering—spontaneous, self-referential thought. Three experiments using probe-caught thought sampling and fMRI showed that sad music was associated with stronger mind-wandering and greater centrality of nodes in the Default Mode Network (DMN). The findings demonstrate that DMN activity can be modulated by the emotional valence of music, suggesting that sad music promotes internally directed cognition. These results have implications for using music in education and clinical settings to influence thought patterns.
Scientific Reports
July 7, 2017
José Á. Morales-García, Mario de la Fuente Revenga, Sandra Alonso‐gil et al.
173 citations
The three main alkaloids of Banisteriopsis caapi—harmine, tetrahydroharmine, and harmaline—along with the harmine metabolite harmol, stimulate adult neurogenesis in vitro. In neurospheres from adult mouse brain progenitor cells, all compounds increased neural stem cell proliferation, migration, and differentiation into adult neurons. This suggests that modulation of brain plasticity may contribute to the antidepressant effects of ayahuasca and expands potential applications of these alkaloids to other brain disorders benefiting from stimulation of endogenous neural precursor niches.
Scientific Reports
November 24, 2020
Julane Andries, Lisa Jerome, Evan Sola et al.
170 citations
A randomized controlled trial tested MDMA-assisted psychotherapy for anxiety in people with life-threatening illnesses. Participants received either MDMA (125 mg) or placebo during two 8-hour psychotherapy sessions. At one month after the second session, the MDMA group showed a greater average reduction in anxiety scores (23.5 points) compared to the placebo group (8.8 points), but the difference did not reach statistical significance. The treatment was well tolerated. After the trial, all participants received open-label MDMA sessions. These preliminary results suggest MDMA-assisted psychotherapy may be a promising approach, but larger trials are needed to confirm its effectiveness.
Scientific Reports
January 15, 2014
Natália Bezerra Mota, Raimundo Furtado, Pedro Maia et al.
159 citations
Analyzing speech graphs from dream reports can distinguish people with schizophrenia from those with bipolar disorder and non-psychotic controls. People with schizophrenia showed reduced speech connectivity in both waking and dream reports, which correlated with negative and cognitive symptoms. People with bipolar disorder were indistinguishable from controls in waking reports but showed significantly less connectivity in dream reports. Dream-related speech graph attributes outperformed psychometric scores and waking data for sorting groups. The findings suggest that dreaming exposes differences in memory processing across individuals while waking dampens distinctions, and point toward a fast, low-cost, language-invariant tool for psychiatric diagnosis.
Scientific Reports
August 1, 2017
Aline Viol, Fernanda Palhano-Fontes, Heloisa Onias et al.
154 citations
The entropic brain hypothesis suggests that psychedelic experiences arise from increased randomness in the brain's functional connectivity. Analyzing resting-state fMRI data from human subjects before and after ingesting ayahuasca, a psychedelic beverage used in Amazonian religious and scientific contexts, researchers found that the Shannon entropy of the brain's degree distribution increased, indicating greater disorder in network connections. Local integration within brain networks increased while global integration decreased. These findings align with the entropic brain hypothesis and relate to users' reports of 'mind-expansion.'
Scientific Reports
January 21, 2021
Laura Kaertner, Michael B. Steinborn, Hannes Kettner et al.
152 citations
A prospective study of weekly psychedelic microdosing found that participants reported improved well-being, emotional stability, and reduced anxiety and depressive symptoms over four weeks. However, baseline positive expectancy scores predicted these improvements, suggesting a significant placebo response. The findings caution against overinterpreting the therapeutic value of microdosing.
Scientific Reports
October 9, 2017
Vanja Dakic, Juliana Minardi Nascimento, Rafaela Costa Sartore et al.
137 citations
5-MeO-DMT, a serotonin-like molecule found in traditional Amerindian medicine, alters the protein landscape of human cerebral organoids. Out of 6,728 identified proteins, 934 were differentially expressed after treatment. Computational analysis confirmed previously reported anti-inflammatory effects and revealed modulation of proteins involved in long-term potentiation, dendritic spine formation, cellular protrusion, microtubule dynamics, and cytoskeletal reorganization. These findings provide initial molecular insights into how this compound may affect human brain metabolism.
Scientific Reports
August 2, 2013
Fábio V. Caixeta, Alianda Maira Cornélio, Robson Scheffer-Teixeira et al.
134 citations
Blocking NMDA receptors with ketamine alters how different brain rhythms interact in the hippocampus, a region critical for memory and attention. In awake rats, ketamine (25, 50, and 75 mg/kg) increased fast brain oscillations (gamma and high-frequency oscillations) across all layers of the CA1-dentate axis, while changes in slower theta waves depended on location. Ketamine also increased phase coherence of fast oscillations across hippocampal layers. The coupling between theta waves and fast oscillations changed in a dose-dependent way: theta-high-frequency coupling increased at all doses, but theta-gamma coupling increased only at the lowest dose and was disrupted at the highest dose. These findings indicate that NMDA receptor blockade disrupts neural coordination patterns linked to cognitive functions impaired in schizophrenia.
Scientific Reports
November 10, 2017
Youge Qu, Chun Yang, Qian Ren et al.
126 citations
In a mouse model of depression induced by chronic social defeat stress, (R)-ketamine, but not the related NMDAR antagonist lanicemine, reversed depression-like behavior and partially restored the composition of gut bacteria, including Bacteroidales, Clostridiales, Ruminococcaceae, and Clostridium. The findings suggest that the antidepressant effects of (R)-ketamine may be partly mediated by its ability to normalize gut microbiota alterations.
Scientific Reports
August 2, 2022
Benno Bremer, Qiong Wu, María Guadalupe Mora Álvarez et al.
125 citations
One month of mindfulness meditation training increases functional connectivity between major large-scale brain networks, particularly the default mode network, salience network, and central executive network. In a study of 46 healthy, meditation-naïve adults, resting-state fMRI scans before and after 31 days of mindfulness training or an active control intervention revealed that mindfulness training strengthened connections between nodes of the default mode and salience networks, and between the salience network and key regions of the central executive network. These connectivity changes may represent a neural mechanism underlying the beneficial effects of mindfulness meditation on health and cognition.
Scientific Reports
June 7, 2016
Joseph Wielgosz, Brianna S. Schuyler, Antoine Lutz et al.
124 citations
Long-term mindfulness meditation practitioners have slower baseline respiration rates than non-meditators, and more intensive retreat practice—but not routine daily practice—is linked to slower breathing, independent of age, gender, and body measures like height, weight, and BMI. Full days of meditation did not immediately change baseline respiration, suggesting the effects are long-term rather than acute. These findings point to stable, generalized changes in respiration from sustained mindfulness training.
Scientific Reports
November 22, 2019
Isaac N Treves, Lawrence Y. Tello, Richard J. Davidson et al.
118 citations
A meta-analysis of 15 studies (17 samples, 879 adults) found a small positive relationship between mindfulness and the accuracy of body awareness, with an effect size of g = 0.21. When analyzed by study design, only randomized controlled trials showed a significant link (g = 0.20). Heterogeneity was low, but low fail-safe N estimates reduce confidence in the findings. The results suggest a small but potentially detectable association between mindfulness and body awareness accuracy.
Scientific Reports
March 5, 2020
José Carlos Bouso, Daniel Jiménez‐garrido, María de Lourdes Gómez-sousa et al.
111 citations
Ayahuasca, a hallucinogenic decoction used in traditional Amazonian medicine, may have therapeutic benefits for psychiatric disorders. In a study of 40 first-time users, nearly half (45%) initially met criteria for a psychiatric disorder; after ayahuasca use, more than 80% of those showed clinical improvements that persisted at 6 months. Questionnaires indicated significant reductions in depression and psychopathology. Long-term users (n=23) had lower depression scores and higher self-transcendence and quality of life compared to first-time users. The authors suggest further controlled and observational studies are warranted to assess risks and benefits.
Scientific Reports
June 27, 2019
Jon G Dean, Tiecheng Liu, Sean Huff et al.
111 citations
The psychedelic compound N,N-dimethyltryptamine (DMT) is produced naturally in mammals, but whether it is made in the brain was unclear. This study found that the enzymes needed to synthesize DMT are present in the cerebral cortex, pineal gland, and choroid plexus of both rats and humans. In rat brain tissues, the two key enzymes were found together, unlike in peripheral tissues. DMT concentrations in the cerebral cortex of behaving rats were similar to those of neurotransmitters like serotonin. DMT levels in the visual cortex rose significantly after cardiac arrest, even without the pineal gland. These findings indicate the rat brain can synthesize and release DMT at neurotransmitter-like levels, suggesting human brains might do the same.
Scientific Reports
November 16, 2017
Keisuke Suzuki, Warrick Roseboom, David J. Schwartzman et al.
111 citations
The Hallucination Machine combines deep convolutional neural networks with panoramic virtual reality to simulate visual hallucinatory experiences without drugs or psychosis. In one experiment, the system induced visual phenomenology similar to classical psychedelics. In a second experiment, the simulated hallucinations did not produce the temporal distortion typically linked to altered states. This tool allows researchers to study altered consciousness without the confounding physiological and cognitive effects of psychoactive substances or psychopathological conditions.
Scientific Reports
September 25, 2023
Rebecka Bremler, Nancy Katati, Parvinder Shergill et al.
102 citations
Negative psychological responses to psychedelics lasting more than 72 hours are real and can include new psychiatric diagnoses or worsened symptoms. In a sample of 32 individuals who completed an online questionnaire, 37.5% received a new psychiatric diagnosis after their psychedelic experience, and 87% experienced anxiety symptoms. Deeper interviews with 15 of the most severe cases revealed potential causes: unsafe environments, unpleasant acute experiences, prior psychological vulnerabilities, high or unknown drug doses, and young age. The findings cannot estimate how common such harms are due to the small, selective sample and study design focused only on negative outcomes.
Scientific Reports
March 26, 2019
Minji Lee, Benjamin Baird, Olivia Gosseries et al.
98 citations
During non-rapid eye movement sleep, conscious experiences are linked to reduced phase-locking at low frequencies (<4 Hz) and lower transitivity and clustering coefficient in delta and theta bands compared to unconsciousness, especially over parietal-occipital regions. No significant differences in Granger-causality patterns between frontal and parietal areas were found. These findings suggest that decreased local connectivity at low frequencies in posterior brain regions may indicate consciousness during sleep.
Scientific Reports
November 30, 2022
Agnieszka Olszewska-Guizzo, Angelia Sia, Anna Fogel et al.
95 citations
Exposure to urban green spaces designed with specific landscape features can boost positive emotions and relaxation-related brain activity. In a study of 74 healthy adults, landscapes rated using the Contemplative Landscape Model (CLM) predicted self-reported emotional valence and arousal, as well as alpha and theta brain waves (indicating relaxation and mindfulness), particularly in outdoor settings. The strongest associations were with features like peace and silence, landscape layers, and archetypal elements. Brain reactivity and arousal differed between lab and outdoor settings, but emotional valence was similar. The findings offer concrete guidelines for designing health-promoting urban green spaces.
Scientific Reports
September 5, 2021
Ramona M. Rodriguiz, Vineet Nadkarni, Christopher R. Means et al.
92 citations
Lysergic acid diethylamide (LSD) produces psychedelic effects through the 5-HT2A serotonin receptor, which activates both Gq and β-arrestin signaling pathways. Using mice lacking either β-arrestin1 or β-arrestin2, researchers found that LSD stimulated motor activities and psychedelic-like behaviors—including head twitches, grooming, retrograde walking, and nose-poking—in normal mice and those missing β-arrestin1, but not in mice missing β-arrestin2. The 5-HT2A antagonist MDL100907 blocked these effects. LSD also disrupted prepulse inhibition in normal and β-arrestin1-knockout mice, but not in β-arrestin2-knockouts. These findings indicate that LSD's psychedelic actions require β-arrestin2 signaling.
Scientific Reports
October 13, 2020
Lucie Bréchet, Denis Brunet, Lampros Perogamvros et al.
92 citations
During non-rapid eye movement (NREM) sleep, brief brain states lasting less than a second, called EEG microstates, determine whether a person will recall a dream upon waking. Two microstates (3 and 4) dominated NREM sleep compared to wakefulness. Within NREM sleep, microstate 3 was more present before dream recall, while microstate 4 was less present. Microstate 3 involved the medial frontal lobe, suggesting deeper local deactivation and executive disconnection that keeps the brain asleep. Microstate 4 involved the occipital cortex, thalamus, and brainstem, and its reduced presence may indicate local activation enabling rich perceptual dream content. The temporal dynamics of these alternating brain states determine whether conscious experience arises during NREM sleep.
Scientific Reports
January 23, 2020
Thomas F. Varley, Andrea I. Luppi, Ioannis Pappas et al.
86 citations
Measures of algorithmic and process complexity, applied to functional MRI BOLD signals from individuals under propofol sedation, vary in their ability to distinguish sedation levels. Temporal complexity measures are more sensitive than topological ones. All measures strongly relate to a single underlying construct—termed 'overall complexity'—which explains most variance in the data, as assessed by principal component analysis. This overall complexity discriminates between sedation levels and propofol serum concentrations, supporting the idea that consciousness is linked to complexity, regardless of how complexity is measured.
Scientific Reports
July 18, 2022
Hadley Rahrig, David R. Vago, Matthew A. Passarelli et al.
83 citations
A meta-analysis of twelve studies (226 mindfulness participants, 204 controls) found that mindfulness training increased resting-state functional connectivity between the left middle cingulate cortex (part of the salience network) and the posterior cingulate cortex (a hub of the default mode network), compared to control conditions. This effect, though small (Hedge's g = 0.234), was statistically significant and showed low heterogeneity across studies. The result supports the idea that mindfulness training enhances communication between brain networks involved in flexible, internally-oriented attentional control. No evidence of publication bias was detected.