PNAS Nexus
December 19, 2023
Guglielmo Foffani
17 citations
Hypnagogic (sleep-onset) and hypnopompic (awakening) experiences, including vivid dream-like perceptions without external stimuli, share neural mechanisms with pathological hallucinations in brain disorders such as Parkinson's disease and psychosis. Lucid dreaming, where the dreamer becomes aware of dreaming, may offer insights into these mechanisms. The authors suggest that studying these common sleep phenomena can illuminate the brain's reality-creation processes and inform understanding of neurological and mental health conditions. Recognizing the continuum between normal sleep experiences and pathological hallucinations could improve diagnosis and treatment of brain disorders.
PNAS Nexus
December 1, 2024
Emilia Fló, Laouen Belloli, Álvaro Cabana et al.
10 citations
Directing attention toward the body's internal signals (interoception) versus external sounds (exteroception) produces distinct brain activity patterns. Exteroceptive attention flattened overall brain wave power, while interoceptive attention reduced brain signal complexity, increased frontal connectivity and theta oscillations, and modulated the heartbeat-evoked potential (HEP). Classifiers using HEP features correctly identified the attentional state in 17 of 20 healthy participants; power spectral density features classified all 20. In five brain-injured patients, one with unresponsive wakefulness syndrome and one with locked-in syndrome showed willful modulation of the HEP, suggesting they could follow commands. These findings highlight how attention shapes sensory processing and may aid diagnosis in disorders of consciousness.
PNAS Nexus
April 1, 2025
Katie Zhou, David de Wied, Robin Carhart-Harris et al.
9 citations
Delusional ideation decreased one month after a planned psychedelic experience, while magical thinking showed no change. Over 30% of participants reported hallucinogen persisting perception disorder (HPPD)-type effects at four weeks, though fewer than 1% found them distressing. Younger age, female gender, a history of psychiatric diagnosis, and baseline trait absorption predicted HPPD-like effects. Lifetime psychedelic use at baseline correlated positively with both magical thinking and delusional ideation, suggesting these traits may correlate with psychedelic use rather than being caused by it.
PNAS Nexus
February 1, 2024
Benjy Barnett, Lau M Andersen, Stephen M Fleming et al.
7 citations
Perceptual vividness—the intensity of conscious experience—varies across different experiences, but how the brain registers this variation is unclear. In other psychological domains like number or reward, magnitude is represented independently of sensory features. Reanalyzing existing magnetoencephalography and functional MRI data from two studies that quantified vividness via subjective awareness and visibility ratings, evidence emerged for content-invariant neural signatures of vividness distributed across visual, parietal, and frontal cortices. These findings suggest that neural correlates of subjective vividness may share properties with magnitude codes in other cognitive domains.
PNAS Nexus
July 1, 2026
David S Jin, Oumayma Agdali, Taruna Yadav et al.
Awareness of action (AoA)—the conscious awareness of one's own actions—is crucial for daily life, yet its neural basis is poorly understood. By developing a game where participants repeatedly made nearly identical moves while distracted, then reported awareness or unawareness of those moves, the authors compared neural activity between aware and unaware actions. On short timescales, aware actions showed larger neurophysiological signals both before and after movement, including volitional and perceptual event-related potentials, frontal midline theta, alpha/beta desynchronization, and increased blink rates. On longer timescales, a novel positive event-related potential preceded only unaware moves, and behavioral and pupillometric evidence indicated decreased attention and arousal concurrent with AoA loss. Three synergistic neural mechanisms were identified: long-term increases in arousal/attentional state, increased motor volitional signals, and increased sensory perceptual signals.
PNAS Nexus
March 1, 2026
Lina Jeantin, Pierre Bourdillon, Marc Guenot et al.
Signal complexity in intracranial electroencephalography (iEEG) recordings from healthy brain tissue decreases with reduced consciousness, being highest during wakefulness and REM sleep and lowest under propofol anesthesia. Complexity is more variable during N2 and N3 sleep stages, and frontoparietal regions show the highest complexity during conscious states. Epileptic cortex exhibits lower complexity than healthy cortex during wake and REM sleep. A random forest classifier reliably classified sleep stages using complexity markers. These normative data support using iEEG signal complexity as a marker of physiological consciousness, cortical integrity, and sleep-stage detection.
PNAS Nexus
September 1, 2025
Xin Luo, Huabin Wang, Xuefeng Xu et al.
Mindfulness meditation reduces gaming and depression severity in people with co-occurring internet gaming disorder and depression more effectively than progressive muscle relaxation. Brain imaging showed that mindfulness meditation decreased activity in the medial frontal gyrus and parahippocampal gyrus while increasing activity in the left lentiform when participants faced gaming cues. It also altered functional connectivity between these regions, suggesting changes in executive control and reward processing. Progressive muscle relaxation produced similar but weaker effects. Mindfulness meditation may be an efficacious treatment for individuals with both conditions.
PNAS Nexus
February 29, 2024
F. Schoeller, Leonardo Christov-Moore, C. Lynch et al.
Individual differences in the experience of aesthetic chills—the feeling of cold and shivers down the spine during peak experiences—are predicted by a combination of age, sex, pre-exposure arousal, predisposition to Kama Muta (KAMF), and absorption (modified tellegen absorption scale [MODTAS]). A study of over 2,900 participants used mass data mining to create a large database of ecologically sourced chills-evoking stimuli, then applied machine learning (LASSO and SVM) and multilevel modeling. These factors predicted the occurrence of chills with 73.5% accuracy and accounted for 48% of the variance in chills intensity. The approach enables assignment of stimuli tailored to individual biopsychosocial profiles, increasing experimental control and revealing how sociocultural factors, psychological traits, and contextual states shape subjective phenomena.