Prestimulus Alpha Phase Modulates Visual Temporal Integration.

When presented shortly after another, discrete pictures are naturally perceived as continuous. The neuronal mechanism underlying such continuous or discrete perception is not well understood. While continuous alpha oscillations are a candidate for orchestrating such neuronal mechanisms, recent evidence is mixed.

Temporal dynamics of oscillatory activity during nonlexical language decoding: Evidence from Morse code and magnetoencephalography.

Understanding encoded languages, such as written script or Morse code, requires nonlexical and lexical processing components that act in a parallel and interactive fashion. Decoding written script-as for example in reading-is typically very fast, making the investigation of the lexical and nonlexical components and their underlying neural mechanisms challenging. In the current study, we aimed to accomplish this problem by using Morse code as a model for language decoding.

The angular gyrus serves as an interface between the non-lexical reading network and the semantic system: evidence from dynamic causal modeling.

Understanding encoded language, such as written words, requires multiple cognitive processes that act in a parallel and interactive fashion. These processes and their interactions, however, are not fully understood. Various conceptual and methodical approaches including computational modeling and neuroimaging have been applied to better understand the neural underpinnings of these complex processes in the human brain.

Saccade suppression of displacements, but not of contrast, depends on context.

Saccades let the visual scene sweep with high speed across the retina, thus producing a massive motion stimulus. Yet, in natural vision, we never perceive motion that is produced by saccades. The absence of perisaccadic motion perception might be caused by a transient reduction of visual sensitivity at the time of saccade initiation, so-called saccadic suppression.

Human movements do not look the same in a tilted world: Gravitational constraints influence the perception of biological motion.

We investigated whether gravitational constraints influence the interaction of visual, proprioceptive and vestibular cues for Biological Motion Perception (BMP). Participants were asked to distinguish between plausible and random point-light movements, while passively placed in either an upright or a tilted body orientation. Manipulating the body orientation with respect to gravity leads to different gravitational signals transmitted by the visual, proprioceptive, and vestibular systems.

10 Hz tACS Over Somatosensory Cortex Does Not Modulate Supra-Threshold Tactile Temporal Discrimination in Humans.

Perception of physical identical stimuli can differ over time depending on the brain state. One marker of this brain state can be neuronal oscillations in the alpha band (8-12 Hz). A previous study showed that the power of prestimulus alpha oscillations in the contralateral somatosensory area negatively correlate with the ability to temporally discriminate between two subsequent tactile suprathreshold stimuli.

Impaired Tactile Temporal Discrimination in Patients With Hepatic Encephalopathy.

The sensory system constantly receives stimuli from the external world. To discriminate two stimuli correctly as two temporally distinct events, the temporal distance or stimulus onset asynchrony (SOA) between the two stimuli has to exceed a specific threshold. If the SOA between two stimuli is shorter than this specific threshold, the two stimuli will be perceptually fused and perceived as one single stimulus.

Connecting occipital alpha band peak frequency, visual temporal resolution, and occipital GABA levels in healthy participants and hepatic encephalopathy patients.

Recent studies have proposed a connection between the individual alpha band peak frequency and the temporal resolution of visual perception in healthy human participants. This connection rests on animal studies describing oscillations in the alpha band as a mode of phasic thalamocortical information transfer for low-level visual stimuli, which critically relies on GABAergic interneurons. Here, we investigated the interplay of these parameters by measuring occipital alpha band peak frequency by means of magnetoencephalography, visual temporal resolution by means of behavioral testing, and occipital GABA levels by means of magnetic resonance spectroscopy.

A new device for high-temperature in situ GISAXS measurements.

A heating stage originally designed for diffraction experiments is implemented into a Bruker NANOSTAR instrument for in situ grazing incidence small-angle x-ray scattering experiments. A controlled atmosphere is provided by a dome separating the sample environment from the evacuated scattering instrument. This dome is double shelled in order to enable cooling water to flow through it.

Event-related desynchronization of mu and beta oscillations during the processing of novel tool names.

According to the embodied cognition framework, the formation of conceptual representations integrates the type of experience during learning. In this electroencephalographic study, we applied a linguistic variant of a training paradigm, in which participants learned to associate novel names to novel tools while either manipulating or visually exploring them. The analysis focused on event-related desynchronization (ERD) of oscillations in the mu and beta frequency range, which reflects activation of sensorimotor brain areas.

U-shaped Relation between Prestimulus Alpha-band and Poststimulus Gamma-band Power in Temporal Tactile Perception in the Human Somatosensory Cortex.

Neuronal oscillations are a ubiquitous phenomenon in the human nervous system. Alpha-band oscillations (8-12 Hz) have been shown to correlate negatively with attention and performance, whereas gamma-band oscillations (40-150 Hz) correlate positively. Here, we studied the relation between prestimulus alpha-band power and poststimulus gamma-band power in a suprathreshold tactile discrimination task.

Rapid temporal recalibration to visuo-tactile stimuli.

For a comprehensive understanding of the environment, the brain must constantly decide whether the incoming information originates from the same source and needs to be integrated into a coherent percept. This integration process is believed to be mediated by temporal integration windows. If presented with temporally asynchronous stimuli for a few minutes, the brain adapts to this new temporal relation by recalibrating the temporal integration windows.

Beyond the Peak - Tactile Temporal Discrimination Does Not Correlate with Individual Peak Frequencies in Somatosensory Cortex.

The human sensory systems constantly receive input from different stimuli. Whether these stimuli are integrated into a coherent percept or segregated and perceived as separate events, is critically determined by the temporal distance of the stimuli. This temporal distance has prompted the concept of temporal integration windows or perceptual cycles.

Subliminal stimuli modulate somatosensory perception rhythmically and provide evidence for discrete perception.

Despite being experienced as continuous, there is an ongoing debate if perception is an intrinsically discrete process, with incoming sensory information treated as a succession of single perceptual cycles. Here, we provide causal evidence that somatosensory perception is composed of discrete perceptual cycles. We used in humans an electrotactile temporal discrimination task preceded by a subliminal (i.

Impaired perception of human movements in Parkinson's disease.

Interacting with other individuals in a social world requires fast and accurate perception of other individuals' identity, actions, or intentions. Humans are very efficient in these social tasks, as they can extract social information even if the actor is represented only by a handful of point-lights on an otherwise invisible body. Theories have argued that efficient visual perception of actions is based on intact motor system functioning.

Beta Peak Frequencies at Rest Correlate with Endogenous GABA+/Cr Concentrations in Sensorimotor Cortex Areas.

Neuronal oscillatory activity in the beta band (15-30 Hz) is a prominent signal within the human sensorimotor cortex. Computational modeling and pharmacological modulation studies suggest an influence of GABAergic interneurons on the generation of beta band oscillations. Accordingly, studies in humans have demonstrated a correlation between GABA concentrations and power of beta band oscillations.

Beta oscillations define discrete perceptual cycles in the somatosensory domain.

Whether seeing a movie, listening to a song, or feeling a breeze on the skin, we coherently experience these stimuli as continuous, seamless percepts. However, there are rare perceptual phenomena that argue against continuous perception but, instead, suggest discrete processing of sensory input. Empirical evidence supporting such a discrete mechanism, however, remains scarce and comes entirely from the visual domain.

Lateralized modulation of beta-band power in sensorimotor areas during action observation.

The cortical network for action observation includes areas of the visual cortex and non-visual areas, including areas of the motoric system. Parts of this network are known for their contralateral organization during motion execution, i.e.

Prestimulus Alpha Power Influences Tactile Temporal Perceptual Discrimination and Confidence in Decisions.

Recent studies have demonstrated that prestimulus alpha-band activity substantially influences perception of near-threshold stimuli. Here, we studied the influence of prestimulus alpha power fluctuations on temporal perceptual discrimination of suprathreshold tactile stimuli and subjects' confidence regarding their perceptual decisions. We investigated how prestimulus alpha-band power influences poststimulus decision-making variables.

The role of alpha oscillations for illusory perception.

Alpha oscillations are a prominent electrophysiological signal measured across a wide range of species and cortical and subcortical sites. Alpha oscillations have been viewed for a long time as an "idling" rhythm, purely reflecting inactive sites. Despite earlier evidence from neurophysiology, awareness that alpha oscillations can substantially influence perception and behavior has grown only recently in cognitive neuroscience.

Distinct spatio-temporal profiles of beta-oscillations within visual and sensorimotor areas during action recognition as revealed by MEG.

The neural correlates of action recognition have been widely studied in visual and sensorimotor areas of the human brain. However, the role of neuronal oscillations involved during the process of action recognition remains unclear. Here, we were interested in how the plausibility of an action modulates neuronal oscillations in visual and sensorimotor areas.

Audio-visual congruency alters power and coherence of oscillatory activity within and between cortical areas.

Dynamic communication between functionally specialized, but spatially distributed areas of the brain is essential for effective brain functioning. A candidate mechanism for effective neuronal communication is oscillatory neuronal synchronization. Here, we used magnetoencephalography (MEG) to study the role of oscillatory neuronal synchronization in audio-visual speech perception.

Reduced occipital alpha power indexes enhanced excitability rather than improved visual perception.

Several studies have demonstrated that prestimulus occipital alpha-band activity substantially influences subjective perception and discrimination of near-threshold or masked visual stimuli. Here, we studied the role of prestimulus power fluctuations in two visual phenomena called double-flash illusion (DFI) and fusion effect (FE), both consisting of suprathreshold stimuli. In both phenomena, human subjects' perception varies on a trial-by-trial basis between perceiving one or two visual stimuli, despite constant stimulation.

Interactions between visual and motor areas during the recognition of plausible actions as revealed by magnetoencephalography.

Several studies have shown activation of the mirror neuron system (MNS), comprising the temporal, posterior parietal, and sensorimotor areas when observing plausible actions, but far less is known on how these cortical areas interact during the recognition of a plausible action. Here, we recorded neural activity with magnetoencephalography while subjects viewed point-light displays of biologically plausible and scrambled versions of actions. We were interested in modulations of oscillatory activity and, specifically, in coupling of oscillatory activity between visual and motor areas.

Fluctuations of prestimulus oscillatory power predict subjective perception of tactile simultaneity.

Oscillatory activity is modulated by sensory stimulation but can also fluctuate in the absence of sensory input. Recent studies have demonstrated that such fluctuations of oscillatory activity can have substantial influence on the perception of subsequent stimuli. In the present study, we employed a simultaneity task in the somatosensory domain to study the role of prestimulus oscillatory activity on the temporal perception of 2 events.