The steady-state visual evoked potential (SSVEP) reflects the activation of cortical object representations: evidence from semantic stimulus repetition.

We applied high-density EEG to examine steady-state visual evoked potentials (SSVEPs) during a perceptual/semantic stimulus repetition design. SSVEPs are evoked oscillatory cortical responses at the same frequency as visual stimuli flickered at this frequency. In repetition designs, stimuli are presented twice with the repetition being task irrelevant.

Electrophysiological correlates of gist perception: a steady-state visually evoked potentials study.

Gist perception refers to perceiving the substance or general meaning of a scene. To investigate its neuronal mechanisms, we used the steady-state visually evoked potential (SSVEP) method-an evoked oscillatory cortical response at the same frequency as a visual stimulus flickered at this frequency. Two neighboring stimuli were flickered at different frequencies f and f, for example, a drawing of a sun on the left side of the screen flickering at 8.

Memory entrainment by visually evoked theta-gamma coupling.

The wake human brain constantly encodes novel information and integrates them into existing neuronal representations. It is posited that the formation of new memory traces is orchestrated by the synchronization of neuronal activity in the theta rhythm (3-8 Hz), theta coupled gamma activity (40-120 Hz), and decreases in the alpha rhythm (8-12 Hz). Critically, given the correlative nature of neurophysiological recordings, the functional relevance of oscillatory processes is not well understood.

Written threat: Electrophysiological evidence for an attention bias to affective words in social anxiety disorder.

Social anxiety disorder (SAD) is associated with heightened sensitivity to threat cues, typically represented by emotional facial expressions. To examine if this bias can be transferred to a general hypersensitivity or whether it is specific to disorder relevant cues, we investigated electrophysiological correlates of emotional word processing (alpha activity and event-related potentials) in 20 healthy participants and 20 participants with SAD. The experimental task was a silent reading of neutral, positive, physically threatening and socially threatening words (the latter were abusive swear words) while responding to a randomly presented dot.

Repetition priming effects dissociate between miniature eye movements and induced gamma-band responses in the human electroencephalogram.

The role of induced gamma-band responses (iGBRs) in the human electroencephalogram (EEG) is a controversial topic. On the one hand, iGBRs have been associated with neuronal activity reflecting the (re-)activation of cortical object representations. On the other hand, it was shown that miniature saccades (MSs) lead to high-frequency artifacts in the EEG that can mimic cortical iGBRs.

Category-selective attention modulates unconscious processes in the middle occipital gyrus.

Many studies have revealed the top-down modulation (spatial attention, attentional load, etc.) on unconscious processing. However, there is little research about how category-selective attention could modulate the unconscious processing.

Functional hemispheric asymmetries of global/local processing mirrored by the steady-state visual evoked potential.

While hemispheric differences in global/local processing have been reported by various studies, it is still under dispute at which processing stage they occur. Primarily, it was assumed that these asymmetries originate from an early perceptual stage. Instead, the content-level binding theory (Hübner & Volberg, 2005) suggests that the hemispheres differ at a later stage at which the stimulus information is bound to its respective level.

Successful memory encoding is associated with increased cross-frequency coupling between frontal theta and posterior gamma oscillations in human scalp-recorded EEG.

Although previous studies have established that successful memory encoding is associated with increased synchronization of theta-band and gamma-band oscillations, it is unclear if there is a functional relationship between oscillations in these frequency bands. Using scalp-recorded EEG in healthy human participants, we demonstrate that cross-frequency coupling between frontal theta phase and posterior gamma power is enhanced during the encoding of visual stimuli which participants later on remember versus items which participants subsequently forget ("subsequent memory effect," SME). Conventional wavelet analyses and source localizations revealed SMEs in spectral power of theta-, alpha-, and gamma-band.

Implicit and explicit contributions to object recognition: evidence from rapid perceptual learning.

The present study investigated implicit and explicit recognition processes of rapidly perceptually learned objects by means of steady-state visual evoked potentials (SSVEP). Participants were initially exposed to object pictures within an incidental learning task (living/non-living categorization). Subsequently, degraded versions of some of these learned pictures were presented together with degraded versions of unlearned pictures and participants had to judge, whether they recognized an object or not.

Cortical reactions to verbal abuse: event-related brain potentials reflecting the processing of socially threatening words.

Human information processing is sensitive to aversive stimuli, in particular to negative cues that indicate a threat to physical integrity. We investigated the extent to which these findings can be transferred to stimuli that are associated with a social rather than a physical threat. Event-related potentials were recorded during silent reading of neutral, positive, physically threatening, and socially threatening words, whereby socially threatening words were represented by swear words.

Sharpening and formation: two distinct neuronal mechanisms of repetition priming.

The repetition of an object stimulus results in faster and better recognition of this object (repetition priming). This phenomenon is neuronally associated with a reduced firing rate of neurons (repetition suppression). It has been interpreted as a sharpening mechanism within the cell assembly representing the object.

Influences of encoding and retrieval on the steady-state visual evoked potential.

The steady-state visual evoked potential (SSVEP) is a powerful tool to study basic perceptual functions in the human electroencephalogram (EEG) (e.g. selective attention).

Perceiving the tree in the woods: segregating brain responses to stimuli constituting natural scenes.

Conventional neuroscientific methods are inadequate for separating the brain responses related to the simultaneous processing of different parts of a natural scene. In the present human electroencephalogram (EEG) study, we overcame this limitation by tagging concurrently presented backgrounds and objects with different presentation frequencies. As a result, background and object elicited different steady-state visual evoked potentials (SSVEPs), which were separately quantified in the frequency domain.

Controlling the unconscious: attentional task sets modulate subliminal semantic and visuomotor processes differentially.

Are unconscious processes susceptible to attentional influences? In two subliminal priming experiments, we investigated whether task sets differentially modulate the sensitivity of unconscious processing pathways. We developed a novel procedure for masked semantic priming of words (Experiment 1) and masked visuomotor priming of geometrical shapes (Experiment 2). Before presentation of the masked prime, participants performed an induction task in which they attended to either semantic or perceptual object features designed to activate a semantic or perceptual task set, respectively.

On the temporal organization of facial identity and expression analysis: Inferences from event-related brain potentials.

In the present study, behavioral and electrophysiological markers of information processing-the lateralized readiness potential, the N170, and the P300-were recorded in order to assess the functional and temporal organization of facial identity and expression processing. A two-choice go/no-go task was used in which facial expression (happy vs. angry) determined response hand and response execution depended on facial familiarity (familiar vs.

Attentional sensitization of unconscious cognition: task sets modulate subsequent masked semantic priming.

According to classical theories, automatic processes are autonomous and independent of higher level cognitive influence. In contrast, the authors propose that automatic processing depends on attentional sensitization of task-congruent processing pathways. In 3 experiments, the authors tested this hypothesis with a modified masked semantic priming paradigm during a lexical decision task by measuring event-related potentials (ERPs): Before masked prime presentation, participants attended an induction task either to semantic or perceptual stimulus features designed to activate a semantic or perceptual task set, respectively.

Steady-state visually evoked potential correlates of object recognition.

In present high density electroencephalogram (EEG) study, we examined steady-state visual evoked potential (SSVEP) correlates of object recognition. In SSVEP tasks a visual stimulus is presented repetitively at a specific flickering rate and typically elicits a continuous oscillatory brain response. This response is characterized by the same fundamental frequency as the initiating stimulus.

Parallel processing in face perception.

The authors examined face perception models with regard to the functional and temporal organization of facial identity and expression analysis. Participants performed a manual 2-choice go/no-go task to classify faces, where response hand depended on facial familiarity (famous vs. unfamiliar) and response execution depended on facial expression (happy vs.

Increased unconscious semantic activation in schizophrenia patients with formal thought disorder.

Formal thought disorder (TD) is a core symptom in schizophrenia, but the underlying neurocognitive mechanisms have yet to be determined. This pilot study tested the hypothesis that unconscious semantic activation in conceptual memory is increased in thought disordered patients with schizophrenia. Twenty-eight right-handed individuals with a DSM-IV diagnosis of schizophrenia or schizophreniform disorder (2 patients) and 14 healthy comparison participants performed lexical decisions on target words that were preceded by semantically related and unrelated unconsciously perceived masked prime words (masked priming paradigm).

Specifying attentional top-down influences on subsequent unconscious semantic processing.

Classical theories assume that unconscious automatic processes are autonomous and independent of higher-level cognitive influences. In contrast, we propose that automatic processing depends on a specific configuration of the cognitive system by top-down control. In 2 experiments, we tested the influence of available attentional resources and previously activated task sets on masked semantic priming in a lexical decision task.

Masked and unmasked electrophysiological repetition effects of famous faces.

We investigated immediate repetition effects of sequentially presented famous face pairs. The first face (F1) was presented masked or unmasked and preceded the second face (F2) with different SOAs (84 ms vs. 500 ms).