Perceptual bias in Gestalt grouping by proximity affected by visual working memory load.

Basic perceptual processes, including perceptual grouping, are subject to bias. Bias for cardinal orientations interferes with Gestalt grouping by proximity in dot lattices. A critical question is whether the bias arises in perceptual encoding or rather is conveyed in a top-down fashion, possibly mediated by visual working memory.

Spatiotemporal survival analysis for movement trajectory tracking in virtual reality.

We present a novel method for analyzing response trajectory tracking data. Limiting behavioral experiments to discrete, key-press response measures, such as reaction times and accuracy, is unsatisfactory for observing the ongoing dynamics of cognition. We assessed the utility of continuous response tracking in Virtual Reality (VR) by comparing it to key-press responses in a classical N-back matching task.

Adaptive rewiring: a general principle for neural network development.

The nervous system, especially the human brain, is characterized by its highly complex network topology. The neurodevelopment of some of its features has been described in terms of dynamic optimization rules. We discuss the principle of adaptive rewiring, i.

Prior EEG marks focused and mind-wandering mental states across trials.

Whether spontaneous or induced by a tedious task, the transition from a focused mental state to mind wandering is a complex one, possibly involving adjacent mental states and extending over minutes or even hours. This complexity cannot be captured by relying solely on subjective reports of mind wandering. To characterize the transition in a mind-wandering-inducing tone counting task, in addition we collected subjective reports of thought generation along with task performance as a measure of cognitive control and EEG measures, namely auditory probe evoked potentials (AEP) and ongoing 8-12 Hz alpha-band amplitude.

Retinal waves in adaptive rewiring networks orchestrate convergence and divergence in the visual system.

Spontaneous retinal wave activity shaping the visual system is a complex neurodevelopmental phenomenon. Retinal ganglion cells are the hubs through which activity diverges throughout the visual system. We consider how these divergent hubs emerge, using an adaptively rewiring neural network model.

Refixation behavior in naturalistic viewing: Methods, mechanisms, and neural correlates.

When freely viewing a scene, the eyes often return to previously visited locations. By tracking eye movements and coregistering eye movements and EEG, such refixations are shown to have multiple roles: repairing insufficient encoding from precursor fixations, supporting ongoing viewing by resampling relevant locations prioritized by precursor fixations, and aiding the construction of memory representations. All these functions of refixation behavior are understood to be underpinned by three oculomotor and cognitive systems and their associated brain structures.

Functional and spatial rewiring principles jointly regulate context-sensitive computation.

Adaptive rewiring provides a basic principle of self-organizing connectivity in evolving neural network topology. By selectively adding connections to regions with intense signal flow and deleting underutilized connections, adaptive rewiring generates optimized brain-like, i.e.

A phase 1/2 trial to assess safety and efficacy of a vaporized 5-methoxy-N,N-dimethyltryptamine formulation (GH001) in patients with treatment-resistant depression.

Background: Treatment-resistant depression (TRD) is a substantial public health burden, but current treatments have limited effectiveness. The aim was to investigate the safety and potential antidepressant effects of the serotonergic psychedelic drug 5-MeO-DMT in a vaporized formulation (GH001) in adult patients with TRD.

Methods: The Phase 1 part ( = 8) of the trial investigated two single dose levels of GH001 (12 mg, 18 mg) with a primary endpoint of safety, and the Phase 2 part ( = 8) investigated an individualized dosing regimen (IDR) with up to three increasing doses of GH001 (6 mg, 12 mg, and 18 mg) within a single day, with a primary endpoint of efficacy, as assessed by the proportion of patients in remission (MADRS ≤ 10) on day 7.

Planning to revisit: Neural activity in refixation precursors.

Eye tracking studies suggest that refixations-fixations to locations previously visited-serve to recover information lost or missed during earlier exploration of a visual scene. These studies have largely ignored the role of precursor fixations-previous fixations on locations the eyes return to later. We consider the possibility that preparations to return later are already made during precursor fixations.

A Bayesian classifier for fractal characterization of short behavioral series.

Serial tasks in behavioral research often lead to correlated responses, invalidating the application of generalized linear models and leaving the analysis of serial correlations as the only viable option. We present a Bayesian analysis method suitable for classifying even relatively short behavioral series according to their correlation structure. Our classifier consists of three phases.

Perceptual bias contextualized in visually ambiguous stimuli.

The visual appearance of an object is a function of stimulus properties as well as perceptual biases imposed by the observer. The context-specific trade-off between both can be measured accurately in a perceptual judgment task, involving grouping by proximity in ambiguous dot lattices. Such grouping depends lawfully on a stimulus parameter of the dot lattices known as their aspect ratio (AR), whose effect is modulated by a perceptual bias representing the preference for a cardinal orientation.

Problem type and externalization in problem-solving.

We compared problem-solving in four sets of classical insight and analytic problems in the verbal and spatial domains, and examined the impact of externalization (verbalization or sketching). In a within-participants factorial design, we presented 24 classical insight and analytic problems, half verbal and half spatial. Participants solved these problems either while thinking aloud, while sketching, or in a baseline condition where neither was allowed.

The No-Report Paradigm: A Revolution in Consciousness Research?

In the cognitive neuroscience of consciousness, participants have commonly been instructed to report their conscious content. This, it was claimed, risks confounding the neural correlates of consciousness (NCC) with their preconditions, i.e.

Adaptive rewiring in nonuniform coupled oscillators.

Structural plasticity of the brain can be represented in a highly simplified form as adaptive rewiring, the relay of connections according to the spontaneous dynamic synchronization in network activity. Adaptive rewiring, over time, leads from initial random networks to brain-like complex networks, that is, networks with modular small-world structures and a rich-club effect. Adaptive rewiring has only been studied, however, in networks of identical oscillators with uniform or random coupling strengths.

A Phase 1, Dose-Ranging Study to Assess Safety and Psychoactive Effects of a Vaporized 5-Methoxy-N, N-Dimethyltryptamine Formulation (GH001) in Healthy Volunteers.

5-Methoxy-N,N-Dimethyltryptamine (5-MeO-DMT) is a tryptamine with ultra-rapid onset and short duration of psychedelic effects. Prospective studies for other tryptamines have suggested beneficial effects on mental health outcomes. In preparation for a study in patients with depression, the present study GH001-HV-101 aimed to assess the impact of four different dose levels of a novel vaporized 5-MeO-DMT formulation (GH001) administered via inhalation as single doses of 2 ( = 4), 6 ( = 6), 12 ( = 4) and 18 mg ( = 4), and in an individualized dose escalation regimen ( = 4) on the safety, tolerability, and the dose-related psychoactive effects in healthy volunteers ( = 22).

Effects of Temporal Expectations on the Perception of Motion Gestalts.

Gestalt psychology has traditionally ignored the role of attention in perception, leading to the view that autonomous processes create perceptual configurations that are then attended. More recent research, however, has shown that spatial attention influences a form of Gestalt perception: the coherence of random-dot kinematograms (RDKs). Using ERPs, we investigated whether temporal expectations exert analogous attentional effects on the perception of coherence level in RDKs.

Adaptive Rewiring in Weighted Networks Shows Specificity, Robustness, and Flexibility.

Brain network connections rewire adaptively in response to neural activity. Adaptive rewiring may be understood as a process which, at its every step, is aimed at optimizing the efficiency of signal diffusion. In evolving model networks, this amounts to creating shortcut connections in regions with high diffusion and pruning where diffusion is low.

Neural correlates of task-related refixation behavior.

Eye movement research has shown that attention shifts from the currently fixated location to the next before a saccade is executed. We investigated whether the cost of the attention shift depends on higher-order processing at the time of fixation, in particular on visual working memory load differences between fixations and refixations on task-relevant items. The attention shift is reflected in EEG activity in the saccade-related potential (SRP).

Adaptive rewiring evolves brain-like structure in weighted networks.

Activity-dependent plasticity refers to a range of mechanisms for adaptively reshaping neuronal connections. We model their common principle in terms of adaptive rewiring of network connectivity, while representing neural activity by diffusion on the network: Where diffusion is intensive, shortcut connections are established, while underused connections are pruned. In binary networks, this process is known to steer initially random networks robustly to high levels of structural complexity, reflecting the global characteristics of brain anatomy: modular or centralized small world topologies.

Large-scale cortical travelling waves predict localized future cortical signals.

Predicting future brain signal is highly sought-after, yet difficult to achieve. To predict the future phase of cortical activity at localized ECoG and MEG recording sites, we exploit its predominant, large-scale, spatiotemporal dynamics. The dynamics are extracted from the brain signal through Fourier analysis and principal components analysis (PCA) only, and cast in a data model that predicts future signal at each site and frequency of interest.

Factoring in the spatial effects of symbolic number representation.

Spatial constituents of adult symbolic number representation produce effects of size-value congruity, Spatial Numerical Association of Response Codes (SNARC), and numerical distance. According to behavioral experiments, these effects belong to distinct processing stages. Yet, these effects evoke overlapping responses in both early and late Event Related Potentials (ERPs).

Refixation patterns reveal memory-encoding strategies in free viewing.

We investigated visual working memory encoding across saccadic eye movements, focusing our analysis on refixation behavior. Over 10-s periods, participants performed a visual search for three, four, or five targets and remembered their orientations for a subsequent change-detection task. In 50% of the trials, one of the targets had its orientation changed.