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Magneto- and electroencephalography (M/EEG) are widespread techniques to measure neural activity in-vivo at a high temporal resolution but low spatial resolution. Locating the neural sources underlying the M/EEG poses an inverse problem, which is ill-posed. We developed a new method based on Recursive Application of Multiple Signal Classification (MUSIC). Our proposed method is able to recover not only the locations but, in contrast to other inverse solutions, also the extent of active brain regions flexibly (FLEX-MUSIC). This is achieved by allowing it to search not only for single dipoles but also dipole clusters of increasing extent to find the best fit during each recursion. FLEX-MUSIC achieved the highest accuracy for both single dipole and extended sources compared to all other methods tested. Remarkably, FLEX-MUSIC was capable to accurately estimate the level of sparsity in the source space (r = 0.82), whereas all other approaches tested failed to do so (r ≤ 0.18). The average computation time of FLEX-MUSIC was considerably lower compared to a popular Bayesian approach and comparable to that of another recursive MUSIC approach and eLORETA. FLEX-MUSIC produces only few errors and was capable to reliably estimate the extent of sources. The accuracy and low computation time of FLEX-MUSIC renders it an improved technique to solve M/EEG inverse problems both in neuroscience research and potentially in pre-surgery diagnostic in epilepsy.

We have investigated sleep paralysis (SP) with an online questionnaire. Our sample consisted of 380 participants who experienced at least one SP. In this paper, we present those parts of the investigation that concern the relationship of SP to extraordinary experiences, paranormal beliefs, and absorption. For this purpose, we used a self-developed German questionnaire on SP experiences, a German questionnaire Fragebogen zur Phänomenologie außergewöhnlicher Erfahrungen (PAGE-R-II), to assess the extent to which people with SP have had other extraordinary experiences, a German translation of the Belief in the Supernatural Scale (BitSS), and a German version of the Tellegen Absorption Scale (TAS). Our hypotheses regarding a positive correlation between the frequency of SP and certain forms of extraordinary experiences as well as paranormal/supernatural beliefs and absorption were only partially confirmed. We found an expected significant correlation between the frequency of SP and the expression on the PAGE dimensions “Dissociation” and “Externality”, but not between the frequency and the other two mentioned scales “Coincidence” and “Internality”. 55 % of participants reported having paranormal experiences during SP. This group had highly significant higher mean scores on the three scales PAGE, BitSS and TAS. Furthermore, the exploratory part revealed interesting correlations between the applied scales and specific hallucinatory perceptions and emotions, which leads us to the assumption that two main types of experiencing SP may exist: one mainly connected with typical negative emotions and a more external focus of experience, and another one, which is more likely accompanied also by positive emotions and by more internally experienced perceptions. This assumption requires further investigations.

INTRODUCTION: There is growing evidence of the beneficial effects of exposure to nature on health and well-being. Time spent in nature can decrease stress, anxiety, depression, and improve mood. In the present study, we compared the experience of a short period of silence in the natural environment of a forest with the same amount of silence in a seminar room. METHODS: We applied an intra-subject design with two 6:30-min sessions of silence in two different environments (forest, seminar room). The participants (n=41) were assigned to four groups. Two groups started with the indoor condition and two groups with the outdoor condition. After 1 week, the two groups were exposed to the other condition. Participants filled out personality-trait scales on meaning in life and belief in oneness with the world, as well as state scales assessing emotional reactions, relaxation, boredom, and the subjective sense of self, time, and space. RESULTS: Participants felt significantly more relaxed and less bored in the forest compared to indoors. They experienced time less intensely, judging it to pass faster and to last shorter in the forest. Regarding trait variables, the higher the search for meaning, the higher oneness beliefs in participants. The higher oneness beliefs, the more positive participants felt during silence in the forest. DISCUSSION: Interest in nature-assisted therapy is increasing in the healthcare sector. Exposure to silence in the natural setting of a forest could prove to be an effective complement to interventions applied in nature-assisted therapy, such as forest therapy.

INTRODUCTION: During observation of the ambiguous Necker cube, our perception suddenly reverses between two about equally possible 3D interpretations. During passive observation, perceptual reversals seem to be sudden and spontaneous. A number of theoretical approaches postulate destabilization of neural representations as a pre-condition for reversals of ambiguous figures. In the current study, we focused on possible Electroencephalogram (EEG) correlates of perceptual destabilization, that may allow prediction of an upcoming perceptual reversal. METHODS: We presented ambiguous Necker cube stimuli in an onset-paradigm and investigated the neural processes underlying endogenous reversals as compared to perceptual stability across two consecutive stimulus presentations. In a separate experimental condition, disambiguated cube variants were alternated randomly, to exogenously induce perceptual reversals. We compared the EEG immediately before and during endogenous Necker cube reversals with corresponding time windows during exogenously induced perceptual reversals of disambiguated cube variants. RESULTS: For the ambiguous Necker cube stimuli, we found the earliest differences in the EEG between reversal trials and stability trials already 1 s before a reversal occurred, at bilateral parietal electrodes. The traces remained similar until approximately 1100 ms before a perceived reversal, became maximally different at around 890 ms (p = 7.59 × 10(-6), Cohen's d = 1.35) and remained different until shortly before offset of the stimulus preceding the reversal. No such patterns were found in the case of disambiguated cube variants. DISCUSSION: The identified EEG effects may reflect destabilized states of neural representations, related to destabilized perceptual states preceding a perceptual reversal. They further indicate that spontaneous Necker cube reversals are most probably not as spontaneous as generally thought. Rather, the destabilization may occur over a longer time scale, at least 1 s before a reversal event, despite the reversal event as such being perceived as spontaneous by the viewer.

The COVID-19 pandemic and associated lockdowns triggered worldwide changes in the daily routines of human experience. The Blursday database provides repeated measures of subjective time and related processes from participants in nine countries tested on 14 questionnaires and 15 behavioural tasks during the COVID-19 pandemic. A total of 2,840 participants completed at least one task, and 439 participants completed all tasks in the first session. The database and all data collection tools are accessible to researchers for studying the effects of social isolation on temporal information processing, time perspective, decision-making, sleep, metacognition, attention, memory, self-perception and mindfulness. Blursday includes quantitative statistics such as sleep patterns, personality traits, psychological well-being and lockdown indices. The database provides quantitative insights on the effects of lockdown (stringency and mobility) and subjective confinement on time perception (duration, passage of time and temporal distances). Perceived isolation affects time perception, and we report an inter-individual central tendency effect in retrospective duration estimation.

Ophthalmological methods have increasingly raised the interest of neuropsychiatric specialists. While the integrity of the retinal cell functions can be evaluated with the electroretinogram (ERG), optical coherence tomography (OCT) allows a structural investigation of retinal layer thicknesses. Previous studies indicate possible functional and structural retinal alterations in patients with schizophrenia. Twenty-five patients with paranoid schizophrenia and 25 healthy controls (HC) matched for age, sex, and smoking status participated in this study. Both, ERG and OCT were applied to obtain further insights into functional and structural retinal alterations. A significantly reduced a-wave amplitude and thickness of the corresponding para- and perifoveal outer nuclear layer (ONL) was detected in patients with paranoid schizophrenia with a positive correlation between both measurement parameters. Amplitude and peak time of the photopic negative response (PhNR) and thickness of the parafoveal ganglion cell layer (GCL) were decreased in patients with schizophrenia compared to HC. Our results show both structural and functional retinal differences between patients with paranoid schizophrenia and HC. We therefore recommend the comprehensive assessment of the visual system of patients with schizophrenia, especially to further investigate the effect of antipsychotic medication, the duration of illness, or other factors such as inflammatory or neurodegenerative processes. Moreover, longitudinal studies are required to investigate whether the functional alterations precede the structural changes.

One of the great challenges in psychiatry is finding reliable biomarkers that may allow for more accurate diagnosis and treatment of patients. Neural variability received increasing attention in recent years as a potential biomarker. In the present explorative study we investigated temporal variability in visually evoked EEG activity in a cohort of 16 adult participants with Asperger Syndrome (AS) and 19 neurotypical (NT) controls. Participants performed a visual oddball task using fine and coarse checkerboard stimuli. We investigated various measures of neural variability and found effects on multiple time scales. (1) As opposed to the previous studies, we found reduced inter-trial variability in the AS group compared to NT. (2) This effect builds up over the entire course of a 5-min experiment and (3) seems to be based on smaller variability of neural background activity in AS compared to NTs. The here reported variability effects come with considerably large effect sizes, making them promising candidates for potentially reliable biomarkers in psychiatric diagnostics. The observed pattern of universality across different time scales and stimulation conditions indicates trait-like effects. Further research with a new and larger set of participants are thus needed to verify or falsify our findings.

This study examined the effects of meditative states in experienced meditators on present-moment awareness, subjective time, and self-awareness while assessing meditation-induced changes in heart-rate variability and breathing rate. A sample of 22 experienced meditators who practiced meditation techniques stressing awareness of the present moment (average 20 years of practice) filled out subjective scales pertaining to sense of time and the bodily self and accomplished a metronome task as an operationalization of present-moment awareness before and after a 20 min meditation session (experimental condition) and a 20 min reading session (control condition) according to a within-subject design. A mixed pattern of increased sympathetic and parasympathetic activity was found during meditation regarding heart-rate measures. Breathing intervals were prolonged during meditation. Participants perceived their body boundaries as less salient during meditation than while reading the story; they also felt time passed more quickly and they paid less attention to time during meditation. No significant differences between conditions became apparent for the metronome task. This is probably the first quantitative study to show how the experience of time during a meditation session is altered together with the sense of the bodily self.

The characteristics of the individual's time perspective in relation to changes in social, economic, and political conditions are of major conceptual interest. We assessed the time orientations of 1588 Ukrainian students living in two different regions (western and south-eastern Ukraine) with the Zimbardo Time Perspective Inventory (ZTPI) before (2010-2013) and during (2014-2016) the socioeconomic, political, and military crises which started in 2014, eight years before the war in 2022. We applied ANOVAs with the ZTPI dimensions as dependent variables and the period of testing (precrisis, postcrisis) as an independent variable for the two Ukrainian regions separately. The time perspectives of residents in the region most distant from the war zone (western), who positively assessed the change in the political situation around 2014, increased in the future time orientation and decreased in the present-fatalistic, past-positive, and 333 present-hedonistic time orientations. The time perspectives of residents in the regions closest to the war zone (southeastern) decreased in the future and increased in the past-negative and present-fatalistic time orientations, reflecting their negative judgments of the events. It is not the crisis itself, but the specific social, economic, and political factors and evaluations which define the time perspectives, which are flexible and adjust to changes during extreme life circumstances.

We investigated sleep paralysis (SP) with an online questionnaire. Our sample consisted of 380 participants who experienced at least one SP. In this paper, we present the relation of SP to extraordinary experiences, paranormal beliefs, and absorption. We used a German questionnaire, Fragebogen zur Phänomenologie außergewöhnlicher Erfahrungen (PAGE-R-II), to assess the extent to which people with SP have had other extraordinary experiences, a German translation of the Belief in the Supernatural Scale (BitSS), and a German version of the Tellegen Absorption Scale (TAS). Our hypotheses regarding a positive correlation between the frequency of SP and certain forms of extraordinary experiences, paranomal/ supernatural beliefs, and absorption were only partially confirmed. We found an expected significant correlation between the frequency of SP and the expression on the PAGE dimensions “Dissociation” and “External,” but not between SP frequency and the other scales. The group (55%) reporting paranormal experiences during SP had highly significant higher mean scores on the PAGE, BitSS, and TAS. There were also significant correlations between the applied scales and specific hallucinatory perceptions and emotions, which leads us to believe that two main types of experiencing SP may exist: one mainly connected with typical negative emotions and a more external focus of experience, and another characterized by positive emotions and more internally experienced perceptions. This hypothesis requires further investigations.

Spaced learning produces better learning performance than extended learning periods without or with little interruptions. This "spacing effect" exists on different time scales, ranging from seconds to months. We recently found large spacing effects with a hitherto rarely investigated 12-hours spacing interval. The present study tested for potentially larger learning effects in the temporal vicinity of 12 h and analyzed spacing effects separately for learning and forgetting. 102 participants learned 40 German-Japanese vocabulary pairs in separate conditions with 7.5 min and 4-, 8-, 12-, and 24-hours spacing intervals. Two final tests were executed after retention intervals of 24 h and 7 days. The 7.5-min spacing interval produced a steeper initial learning curve than all other spacing intervals. 24 h after the last learning unit, we found almost no forgetting in the 4-, 8- and 12-hours spacing conditions, but about 9.3% and 3.6% forgetting in the 7.5 min and 24 h spacing conditions. After 7 days, forgetting was in the range of 13% for all conditions between 4 and 24 h. The 7.5 min condition produced 34% forgetting. Our results indicate that spacing intervals in the range of 8 h ± 4 h provide high learning performance and can be easily integrated in our daily schedules.