Biology subjects

Reckweg, J. T.

Publications and source records attributed to Reckweg, J. T..

4 recordsLinked to original sources

bioRxiv2026

Tuning in together: LSD enhances inter-brain synchrony and felt connectedness in romantic couples

Social connection is fundamental to human wellbeing. Serotonergic psychedelics such as lysergic acid diethylamide (LSD) acutely heighten subjective connectedness, yet their effects on real-time social connection remain poorly understood. Using EEG hyperscanning in a randomized, double-blind, placebo-controlled crossover study, we recorded neural activity simultaneously from both members of healthy romantic couples (N=25) who received LSD (50 g) or placebo together, across resting and interactive states. LSD increased subjective connectedness, including feelings of love, closeness, trust, and being "in sync," while reducing loneliness, compared to placebo. This affiliative shift dissociated from the drugs pharmacokinetic time-course, remaining elevated as subjective intensity and plasma concentration declined. In parallel, LSD increased inter-brain synchrony during shared rest, carried specifically by theta-band amplitude-envelope coupling. Importantly, this effect survived two complementary controls. First, it exceeded coupling between unrelated individuals and second the effects depended on contemporaneous neural alignment rather than shared drug-induced dynamics. Exploratory analyses showed that romantic partners with greater resting synchrony reported greater feelings of connectedness. These findings provide the first evidence that a psychedelic enhances brain-to-brain coupling between people, linking a pharmacologically induced state of felt connection to a measurable signature shared across interacting brains.

neuroscience↗

bioRxiv2026

Psilocybin acutely dissociates cognitive and affective empathy, with empathic concern predicting persisting positive psychological effects

BackgroundPsychedelics have been proposed to enhance empathy and social connectedness, but it remains unclear whether these effects reflect global increases in empathic ability, whether they persist beyond the acute drug state, and whether they contribute to later psychological outcomes. MethodsIn a randomized, double-blind, placebo-controlled, parallel-group study, healthy participants received psilocybin (0.17 mg/kg) or placebo. Three dissociable components of empathy were assessed using the Multifaceted Empathy Test at baseline, during the acute drug state, and 7 days later: cognitive empathy (accuracy of emotion identification), emotional arousal (affective activation in response to anothers emotional state) and empathic concern (other-oriented compassion toward the depicted person. Persisting positive psychological effects were assessed at follow-up. Circulating oxytocin was measured, and spectral dynamic causal modeling was applied to resting-state fMRI data acquired during the acute drug state to examine effective connectivity within an empathy-relevant network. ResultsCompared with placebo, psilocybin acutely reduced cognitive empathy selectively for positive stimuli, while increasing emotional arousal for positive stimuli and empathic concern across valences. These empathy-related effects did not persist 7 days later. However, acute increases in empathic concern mediated later positive psychological changes, including improved attitudes about life and self, mood, and relationships. Psilocybin also increased circulating oxytocin compared to baseline, but oxytocin changes were not associated with empathy changes. Effective-connectivity analyses showed that empathic responding under psilocybin was associated with altered directional coupling among superior temporal and parahippocampal regions. ConclusionsPsilocybin does not simply enhance empathy, rather it impairs the identification of positive emotional states while heightening affective engagement and concern. Although these effects do not persist, acute empathic concern may contribute to later positive psychological change.

neuroscience↗

bioRxiv2023

Assessment of the acute effects of 2C-B vs psilocybin on subjective experience, mood and cognition

2,5-dimethoxy-4-bromophenethylamine (2C-B) is a hallucinogenic phenethylamine derived from mescaline. Observational and preclinical data have suggested it to be capable of producing both subjective and emotional effects on par with other classical psychedelics and entactogens. Whereas it is the most prevalently used novel serotonergic hallucinogen to date, its acute effects and distinctions from classical progenitors have yet to be characterised in a controlled study. We assessed for the first time the immediate acute subjective, cognitive, and cardiovascular effects of 2C-B (20 mg) in comparison to psilocybin (15mg) and placebo in a within-subjects, double-blind, placebo-controlled study of 22 healthy psychedelic-experienced participants. 2C-B elicited alterations of waking consciousness of a psychedelic nature, with dysphoria, subjective impairment, auditory alterations, and affective elements of ego dissolution largest under psilocybin. Participants demonstrated equivalent psychomotor slowing and spatial memory impairments under either compound compared to placebo, as indexed by the Digit Symbol Substitution Test (DSST), Tower of London (TOL) and Spatial Memory Task (SMT). Neither compound produced empathogenic effects on the Multifaceted Empathy Test (MET). 2C-B induced transient pressor effects to a similar degree as psilocybin. The duration of self-reported effects of 2C-B was shorter than that of psilocybin, largely resolving within 6 hours. Present findings support the categorisation of 2C-B as a subjectively "lighter" psychedelic. Tailored dose-effect studies are needed to discern the pharmacokinetic dependency of 2C-Bs experiential overlaps.

pharmacology and toxicology↗

bioRxiv2022

Ritualistic use of ayahuasca enhances a shared functional connectome identity with others.

The knowledge that brain functional connectomes are both unique and reliable has enabled behaviourally relevant inferences at a subject level. However, it is unknown whether such "fingerprints" persist under altered states of consciousness. Ayahuasca is a potent serotonergic psychedelic which elicits a widespread dysregulation of functional connectivity. Used communally in religious ceremonies, its shared use may highlight relevant novel interactions between mental state and FC inherency. Using 7T fMRI, we assessed resting-state static and dynamic FCs for 21 Santo Daime members after collective ayahuasca intake in an acute, within-subject study. Here, connectome fingerprinting revealed a shared functional space, accompanied by a spatiotemporal reallocation of keypoint edges. Importantly, we show that interindividual differences in higher-order FCs motifs are relevant to experiential phenotypes, given that they can predict perceptual drug effects. Collectively, our findings offer an example as to how individualised connectivity markers can be used to trace a subjects functional connectome across altered states of consciousness.

neuroscience↗