The International Journal of Neuropsychopharmacology
June 7, 2012
Wallace C. Duncan, Simone Sarasso, Fabio Ferrarelli et al.
253 citations
A single infusion of the NMDA receptor antagonist ketamine rapidly reduces depressive symptoms in patients with treatment-resistant major depressive disorder. In 30 patients, ketamine increased electroencephalogram slow wave activity during early non-REM sleep and raised plasma levels of brain-derived neurotrophic factor. The occurrence of high amplitude slow waves and their slope also increased, indicating enhanced synaptic strength. Changes in BDNF levels correlated with changes in EEG parameters, but only in patients who responded to ketamine. This suggests that enhanced synaptic plasticity, reflected by increased slow wave activity and BDNF, is part of the mechanism behind ketamine's rapid antidepressant effects.
Cognitive Neuroscience
July 1, 2010
Marcello Massimini, Fabio Ferrarelli, Michael J. Murphy et al.
205 citations
During the first REM sleep episode of the night, transcranial magnetic stimulation (TMS) triggered widespread and differentiated patterns of cortical activation on electroencephalography (EEG), similar to those observed during wakefulness. In contrast, during NREM sleep, cortical activations became more local and stereotypical, indicating impaired intracortical dialogue. These findings suggest that TMS combined with high-density EEG can probe the internal dialogue of the thalamocortical system, potentially offering a method to assess brain function in patients who are unable to move or communicate.
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.
Journal of Cognitive Neuroscience
May 31, 2017
Lampros Perogamvros, Benjamin Baird, Mitja Seibold et al.
76 citations
Spontaneous thoughts occur during wakefulness, NREM sleep, and REM sleep, and all share activation in the midcingulate cortex. Waking thoughts additionally involve a medial prefrontal region linked to metacognition and have more metacognitive content than sleep thoughts. REM sleep thoughts are more social in content. The findings suggest a core neural substrate for thoughts across behavioral states, with medial prefrontal regions contributing to metacognitive qualities during wake.
Scientific Reports
November 5, 2018
Matthieu Darracq, Chadd M. Funk, Daniel Polyakov et al.
49 citations
Sleep and anesthesia alter conscious experience, which can be absent (unconsciousness) or take the form of dreaming where sensory stimuli are not incorporated (disconnected consciousness). Using transcranial magnetic stimulation-electroencephalography over parietal regions, evoked alpha power (8-12 Hz) decreased during disconnected consciousness in rapid eye movement sleep and ketamine anesthesia compared to wakefulness. In unconscious states of propofol anesthesia and non-rapid eye movement sleep, evoked low-gamma power (30-40 Hz) decreased compared to wakefulness or disconnected consciousness. These findings, confirmed with dream reports from serial awakenings, suggest suppression of evoked alpha activity may mark sensory disconnection.
PLoS One
February 22, 2016
Daniela Dentico, Fabio Ferrarelli, Brady A. Riedner et al.
43 citations
After two intensive days of mindfulness or compassion meditation, long-term meditators showed increased low-frequency brain activity (1-12 Hz, peaking around 7-8 Hz) over prefrontal and left parietal areas during non-rapid eye movement sleep. This increase was strongest early in the night and extended to higher frequencies (25-40 Hz) during the third sleep cycle. The changes depended on meditation experience and did not differ between the two meditation styles. No such changes occurred in meditation-naive individuals. The findings suggest that intensive meditation practice acutely alters brain activity in regions linked to top-down regulation, complementing chronic changes seen in posterior areas.
Psychology of consciousness (Washington, D.C.)
March 1, 2019
Benjamin Baird, Brady A. Riedner, Melanie Boly et al.
41 citations
Lucid dreaming occurs more often in long-term meditators than in people who do not meditate. Among non-meditators, lucid dream frequency is linked to the ability to put experience into words, while among meditators it is linked to observing and decentering aspects of mindfulness. However, an 8-week mindfulness course did not increase lucid dream frequency. The findings suggest a continuity between awareness during waking and sleeping states and connect meditation training with meta-awareness, but the precise nature of the link remains unclear.
European Journal of Neuroscience
August 24, 2018
Daniela Dentico, David R. W. Bachhuber, Brady A. Riedner et al.
18 citations
Long-term meditators showed increased low- and fast-frequency brain oscillations during wakefulness after two 8-hour sessions of mindfulness or compassion-and-loving-kindness meditation, peaking at 8 and 15 Hz over prefrontal and left centro-parietal electrodes. These waking changes correlated with previously observed meditation-related increases in low-frequency NREM sleep EEG activity (4-12 Hz), particularly in the theta-alpha range. The findings suggest that sleep homeostatic response alone cannot explain the post-meditation sleep changes; instead, a reverberation of meditation-related processes during subsequent sleep may be involved. No differences emerged between meditation styles or in meditation-naïve participants.
Consciousness and Cognition
January 1, 2022
Benjamin Baird, Mariel Kalkach Aparicio, Tariq Alauddin et al.
17 citations
Spontaneous episodic thoughts about the past and future are common during waking but rarely occur during N2 or REM sleep. Analysis of thought reports from 138 participants who underwent experience-sampling while awake and serial awakenings during sleep shows that waking spontaneous thought frequently includes autobiographical planning with a strong bias toward the future. In contrast, dreaming sleep states rarely feature such mental time travel. This suggests that human consciousness differs substantially across the sleep-wake cycle in how it typically engages with episodic past and future events.
Translational Psychiatry
September 12, 2024
Christopher R. Nicholas, Matthew I Banks, Richard C Lennertz et al.
10 citations
Psilocybin, a serotonergic psychedelic, can relieve symptoms in several psychiatric disorders and improve well-being, but it was unclear whether these benefits arise during the acute experience or depend on later memory of it. In 8 healthy participants, psilocybin (25 mg) was co-administered with the amnestic benzodiazepine midazolam at a dose that allowed a conscious psychedelic experience while partially impairing memory for it. Higher midazolam doses and greater memory impairment tended to associate with lower salience, insight, and well-being from psilocybin. These results suggest memory plays a role in therapeutically relevant behavioral effects of psilocybin.
bioRxiv (Cold Spring Harbor Laboratory)
June 13, 2024
Christopher R. Nicholas, Matthew I. Banks, Richard C Lennertz et al.
3 citations
preprint
Co-administering the amnestic benzodiazepine midazolam with psilocybin in 8 healthy participants partially impaired memory for the psychedelic experience while still allowing a conscious experience to occur. The degree of memory impairment was inversely associated with salience, insight, and well-being induced by psilocybin. These results suggest that memory of the acute psychedelic experience contributes to therapeutically relevant behavioral effects. Because midazolam blocks memory by blocking cortical neural plasticity, it may also help evaluate how the pro-neuroplastic properties of psychedelics contribute to their therapeutic activity.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
June 16, 2026
Nadia S. Hejazi, Mina Kheirkhah, Brady A. Riedner et al.
Slow-wave activity (SWA) during early non-rapid eye movement sleep is lower in people with treatment-resistant depression (TRD) than in healthy volunteers. Ketamine, but not placebo, increases SWA in TRD patients, especially those who respond to treatment, while having no effect on SWA in healthy volunteers. Ketamine also improves overall sleep in TRD patients by increasing total sleep time and sleep efficiency and reducing sleep latency. The increase in SWA after ketamine lessens with age. The findings suggest that ketamine's antidepressant effects are closely tied to its modulation of early sleep SWA and its ability to improve sleep architecture in TRD.
bioRxiv (Cold Spring Harbor Laboratory)
July 29, 2025
May Kung Sutherland, Christopher R. Nicholas, Richard C Lennertz et al.
preprint
Psilocybin, a serotonergic psychedelic, induces neural plasticity and alters consciousness, while midazolam, a benzodiazepine, blunts plasticity and causes sedation and amnesia. In an open-label pilot study, 25 mg of oral psilocybin was given alongside intravenous midazolam at doses that allowed a full psychedelic experience but reduced memory of it. EEG recordings showed that 15-30 minutes after dosing, when midazolam was at its target concentration, beta power increased and the spectral exponent decreased. As psilocybin's effects emerged over the next six hours, Lempel-Ziv complexity and spectral exponent increased while broadband power decreased. These findings suggest psilocybin's effects persist even with midazolam, supporting its use in mechanistic studies.
Translational Psychiatry
February 14, 2026
Michael H Sutherland, Christopher R. Nicholas, Richard C Lennertz et al.
Psilocybin, a serotonergic psychedelic, induces neural plasticity and alters consciousness, while midazolam, a benzodiazepine, blunts plasticity and induces sedation. In an open-label pilot study, 25 mg of oral psilocybin was given alongside intravenous midazolam at doses that allowed a full psychedelic experience but blunted memory. Electroencephalography (EEG) data showed that 15–30 minutes after dosing, when midazolam was at its target concentration, beta power increased and spectral exponent decreased. As psilocybin's effects emerged over the next six hours, Lempel-Ziv complexity and spectral exponent increased, while broadband power decreased, especially in delta, theta, and alpha bands. The findings suggest psilocybin's effects persist with midazolam, supporting its use in mechanistic studies.