Eyes are central to face processing however their role in early face encoding as reflected by the N170 ERP component is unclear. Using eye tracking to enforce fixation on specific facial features, we found that the N170 was larger for fixation on the eyes compared to fixation on the forehead, nasion, nose or mouth, which all yielded similar amplitudes. This eye sensitivity was seen in both upright and inverted faces and was lost in eyeless faces, demonstrating it was due to the presence of eyes at fovea. Upright eyeless faces elicited largest N170 at nose fixation. Importantly, the N170 face inversion effect (FIE) was strongly attenuated in eyeless faces when fixation was on the eyes but was less attenuated for nose fixation and was normal when fixation was on the mouth. These results suggest the impact of eye removal on the N170 FIE is a function of the angular distance between the fixated feature and the eye location. We propose the Lateral Inhibition, Face Template and Eye Detector based (LIFTED) model which accounts for all the present N170 results including the FIE and its interaction with eye removal. Although eyes elicit the largest N170 response, reflecting the activity of an eye detector, the processing of upright faces is holistic and entails an inhibitory mechanism from neurons coding parafoveal information onto neurons coding foveal information. The LIFTED model provides a neuronal account of holistic and featural processing involved in upright and inverted faces and offers precise predictions for further testing.

Microdosing psychedelicsthe regular consumption of small amounts of psychedelic substances such as LSD or psilocybinis a growing trend in popular culture. Recent studies on full-dose psychedelic psychotherapy reveal promising benefits for mental well-being, especially for depression and end-of-life anxiety. While full-dose therapies include perception-distorting properties, microdosing may provide complementary clinical benefits using lower-risk, nonhallucinogenic doses. No experimental study has evaluated psychedelic microdosing, however; this pre-registered study is the first to investigate microdosing psychedelics and mental health. Recruited from online forums, current and former microdosers scored lower on measures of dysfunctional attitudes and negative emotionality and higher on wisdom, open-mindedness, and creativity when compared to non-microdosing controls. These findings provide promising initial evidence that warrants controlled experimental research to directly test safety and clinical efficacy. As microdoses are easier to administer than full-doses, this new paradigm has the exciting potential to shape future psychedelic research.

Background Microdosing psychedelics is the practice of consuming very low, sub-hallucinogenic doses of a psychedelic substance, such as lysergic acid diethylamide (LSD) or psilocybin-containing mushrooms. According to media reports, microdosing has grown in popularity, yet the scientific literature contains minimal research on this practice. There has been limited reporting on adverse events associated with microdosing, and the experiences of microdosers in community samples have not been categorized. Methods In the present study, we develop a codebook of microdosing benefits and challenges (MDBC) based on the qualitative reports of a real-world sample of 278 microdosers. Results We describe novel findings, both in terms of beneficial outcomes, such as improved mood (26.6%) and focus (14.8%), and in terms of challenging outcomes, such as physiological discomfort (18.0%) and increased anxiety (6.7%). We also show parallels between benefits and drawbacks and discuss the implications of these results. We probe for substance-dependent differences, finding that psilocybin-only users report the benefits of microdosing were more important than other users report. Conclusions These mixed-methods results help summarize and frame the experiences reported by an active microdosing community as high-potential avenues for future scientific research. The MDBC taxonomy reported here informs future research, leveraging participant reports to distil the highest-potential intervention targets so research funding can be efficiently allocated. Microdosing research complements the full-dose literature as clinical treatments are developed and neuropharmacological mechanisms are sought. This framework aims to inform researchers and clinicians as experimental microdosing research begins in earnest in the years to come. Electronic supplementary material The online version of this article (10.1186/s12954-019-0308-4) contains supplementary material, which is available to authorized users.

Rationale: Microdosing psychedelics – the practice of consuming small, sub-hallucinogenic doses of substances such as LSD or psilocybin – is gaining attention in popular media but remains poorly characterized. Contemporary studies of psychedelic microdosing have yet to report the basic psychiatric descriptors of psychedelic microdosers. Objectives: To examine the practices and demographics of a population of psychedelic microdosers – including their psychiatric diagnoses, prescription medications, and recreational substance use patterns – to develop a foundation on which to conduct future clinical research. Methods: Participants ( n = 909; Mage = 26.9, SD = 8.6; male = 83.2%; White/European = 79.1%) recruited primarily from the online forum Reddit completed an anonymous online survey. Respondents who reported using LSD, psilocybin, or both for microdosing were grouped and compared with non-microdosing respondents using exploratory odds ratio testing on demographic variables, rates of psychiatric diagnoses, and past-year recreational substance use. Results: Of microdosers, most reported using LSD (59.3%; Mdose = 13 mcg, or 11.3% of one tab) or psilocybin (25.9%; Mdose = 0.3 g of dried psilocybin mushrooms) on a one-day-on, two-days-off schedule. Compared with non-microdosers, microdosers were significantly less likely to report a history of substance use disorders (SUDs; OR = 0.17 (95% CI: 0.05–0.56)) or anxiety disorders (OR = 0.61 (95% CI: 0.41–0.91)). Microdosers were also more likely to report recent recreational substance use compared with non-microdosers (OR = 5.2 (95% CI: 2.7–10.8)). Conclusions: Well-designed randomized controlled trials are needed to evaluate the safety and tolerability of this practice in clinical populations and to test claims about potential benefits.

Science requires replicable tools to measure its intended constructs. Attention research has developed tools that have been used in mind-wandering research, but mind-wandering measures often rely on response-inhibition, which introduces speed-accuracy trade-offs that may conflate errors for mind-wandering. We sought to replicate three studies that used an improved mindwandering measure: the Metronome Response Task (MRT). In a large (N=300) multisite sample, the primary MRT finding was replicated, showing that continuous rhythmic response time variability reliably predicted self-reported mind-wandering. Our findings also show previously undetected differences between intentional and unintentional mind-wandering. While previously reported mediators (motivation) and moderators (confidence) did not replicate, additional covariates add predictive value and additional constructs (e.g., boredom, effort) demonstrate convergent validity. The MRT is useful for inducing and measuring mind-wandering and provides an especially replicable tool. The MRT's measurement of attention could support future models of the complete cycle of sustained attention.