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Arno Villringer - One of the best experts on this subject based on the ideXlab platform.
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pb 7 the role of rolandic alpha activity on processing of Subliminal and supraliminal somatosensory Stimulation during selective spatial attention
Clinical Neurophysiology, 2017Co-Authors: Norman Forschack, Arno Villringer, Till Nierhaus, Matthias M MullerAbstract:Research questions We investigated, whether attentional modulation of somatosensory evoked potentials (SEPs) are mediated by variations in the rolandic alpha-rhythm. Furthermore, we asked whether the attention effect is limited to consciously perceivable (i.e. supraliminal) stimuli, or also applies to imperceptible (i.e. Subliminal) Stimulation. Methods To address these questions, we recorded EEG in healthy volunteers (n = 40) undergoing supraliminal and Subliminal finger nerve Stimulation at the left or right index finger and identified both oscillatory activity and SEPs. Participants performed the following detection task: Spatial attention should be directed either to the left or the right index finger and participants indicated perception of stimuli only at the attended finger. Results Detection rates for supraliminal Stimulation was 71%, when attention was on the left and 74%, when it was on the right finger, respectively (detection rates for Subliminal Stimulation ∼ 0%). In the EEG, selective spatial attention increased SEP-amplitudes (in a time window 50–60 ms after Stimulation; P1) both to supraliminal and Subliminal Stimulation. Mu-rhythm amplitudes directly preceding Stimulation showed a negative quadratic relationship to P1-amplitudes under attention, which reversed, when the stimulated finger was not attended. I.e. the same mu-rhythm amplitude was associated with the highest P1-amplitudes during attention and smallest P1-amplitudes during lack of attention. Conclusion The modulation of the mu-rhythm obviously seems to support the behavioral goal: ‘detect’ stimuli at the cued while ‘ignoring’ the other index finger. To summarize, our results show, that – firstly – selective spatial attention enhances central processing of supraliminal as well as Subliminal Stimulation and – secondly – they underline the importance of mu-rhythm activity in mediating the effect of attention on stimulus processing.
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decreased visual detection during Subliminal Stimulation
Journal of Vision, 2014Co-Authors: Isabelle Bareither, Arno Villringer, Niko A BuschAbstract:: What is the perceptual fate of invisible stimuli-are they processed at all and does their processing have consequences for the perception of other stimuli? As has been shown previously in the somatosensory system, even stimuli that are too weak to be consciously detected can influence our perception: Subliminal Stimulation impairs perception of near-threshold stimuli and causes a functional deactivation in the somatosensory cortex. In a recent study, we showed that Subliminal visual stimuli lead to similar responses, indicated by an increase in alpha-band power as measured with electroencephalography (EEG). In the current study, we investigated whether a behavioral inhibitory mechanism also exists within the visual system. We tested the detection of peripheral visual target stimuli under three different conditions: Target stimuli were presented alone or embedded in a concurrent train of Subliminal stimuli either at the same location as the target or in the opposite hemifield. Subliminal stimuli were invisible due to their low contrast, not due to a masking procedure. We demonstrate that target detection was impaired by the Subliminal stimuli, but only when they were presented at the same location as the target. This finding indicates that Subliminal, low-intensity stimuli induce a similar inhibitory effect in the visual system as has been observed in the somatosensory system. In line with previous reports, we propose that the function underlying this effect is the inhibition of spurious noise by the visual system.
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Neurophysiological investigations into the human somatosensory system
2014 International Winter Workshop on Brain-Computer Interface (BCI), 2014Co-Authors: Arno VillringerAbstract:Using noninvasive neuroimaging methods in human subjects, we attempt to understand functional neuroanatomy and neurophysiological processes (somatotopy, inhibition, excitation, spike bursts, background activity) underlying somatosensory function. In order to define functional neuroanatomy, we use mainly task-based fMRI to identify somatotopy e.g., in SI and SII. Recently, we showed that gross somatotopy can also be extracted from task-less resting-state fMRI. Regarding neurophysiological processes, we show that the strength of background rhythms (Rolandic alpha, beta rhythm) determines receptiveness of the somatosensory system to activation and is inversely related to cortical BOLD-fMRI signal. We establish a model of predominant inhibitory processing using Subliminal Stimulation and we show that this decreases BOLD-fMRI signal, decreases connectivity of SI, and transiently increases alpha rhythm. Using simultaneous EEG-fMRI, we identify correlates of spike bursts in human subjects non-invasively and relate them to BOLD fMRI signal along the path of somatosensory processing.
Niko A Busch - One of the best experts on this subject based on the ideXlab platform.
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decreased visual detection during Subliminal Stimulation
Journal of Vision, 2014Co-Authors: Isabelle Bareither, Arno Villringer, Niko A BuschAbstract:: What is the perceptual fate of invisible stimuli-are they processed at all and does their processing have consequences for the perception of other stimuli? As has been shown previously in the somatosensory system, even stimuli that are too weak to be consciously detected can influence our perception: Subliminal Stimulation impairs perception of near-threshold stimuli and causes a functional deactivation in the somatosensory cortex. In a recent study, we showed that Subliminal visual stimuli lead to similar responses, indicated by an increase in alpha-band power as measured with electroencephalography (EEG). In the current study, we investigated whether a behavioral inhibitory mechanism also exists within the visual system. We tested the detection of peripheral visual target stimuli under three different conditions: Target stimuli were presented alone or embedded in a concurrent train of Subliminal stimuli either at the same location as the target or in the opposite hemifield. Subliminal stimuli were invisible due to their low contrast, not due to a masking procedure. We demonstrate that target detection was impaired by the Subliminal stimuli, but only when they were presented at the same location as the target. This finding indicates that Subliminal, low-intensity stimuli induce a similar inhibitory effect in the visual system as has been observed in the somatosensory system. In line with previous reports, we propose that the function underlying this effect is the inhibition of spurious noise by the visual system.
Isabelle Bareither - One of the best experts on this subject based on the ideXlab platform.
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decreased visual detection during Subliminal Stimulation
Journal of Vision, 2014Co-Authors: Isabelle Bareither, Arno Villringer, Niko A BuschAbstract:: What is the perceptual fate of invisible stimuli-are they processed at all and does their processing have consequences for the perception of other stimuli? As has been shown previously in the somatosensory system, even stimuli that are too weak to be consciously detected can influence our perception: Subliminal Stimulation impairs perception of near-threshold stimuli and causes a functional deactivation in the somatosensory cortex. In a recent study, we showed that Subliminal visual stimuli lead to similar responses, indicated by an increase in alpha-band power as measured with electroencephalography (EEG). In the current study, we investigated whether a behavioral inhibitory mechanism also exists within the visual system. We tested the detection of peripheral visual target stimuli under three different conditions: Target stimuli were presented alone or embedded in a concurrent train of Subliminal stimuli either at the same location as the target or in the opposite hemifield. Subliminal stimuli were invisible due to their low contrast, not due to a masking procedure. We demonstrate that target detection was impaired by the Subliminal stimuli, but only when they were presented at the same location as the target. This finding indicates that Subliminal, low-intensity stimuli induce a similar inhibitory effect in the visual system as has been observed in the somatosensory system. In line with previous reports, we propose that the function underlying this effect is the inhibition of spurious noise by the visual system.
Andreas Birgegard - One of the best experts on this subject based on the ideXlab platform.
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persistent effects of Subliminal Stimulation sex differences and the effectiveness of debriefing
Scandinavian Journal of Psychology, 2007Co-Authors: Andreas Birgegard, Staffan SohlbergAbstract:Persistent and non-trivial effects of unconscious stimuli have been reported (Sohlberg & Birgegard, 2003). This raises the ethical question of whether informing participants about such stimuli effectively returns them to a normal state. Two experiments (sex-mixed, N = 70 and 118) tested two kinds of debriefing to participants following Subliminal (tachistoscopic) attachment-related or control Stimulation. Measures were the Beck Depression Inventory, Structural Analysis of Social Behavior, and Retrospective Attachment. Results showed persistent effects. Simple debriefing about the stimulus was effective in preventing these, while more elaborate debriefing also describing the effects and mechanisms for them was less effective. Persistent effects were also strongly related to participant sex, but debriefing effects were similar in men and women with regard to the purpose of debriefing. The findings have implications for ethical recommendations for Subliminal research, and suggest that this unexplored area requires more attention.
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The Correspondence between Attachment to Parents and God: Three Experiments Using Subliminal Separation Cues
Personality and Social Psychology Bulletin, 2004Co-Authors: Andreas Birgegard, Pehr GranqvistAbstract:Attachment theoretical studies have increased our understanding of the socioemotional foundations for religious development. However, because these studies have been correlational and based on self-reports, they are vulnerable to concerns of self-presentation bias and lack of basis for causal inference. Three Subliminal Stimulation experiments were therefore performed, where activation of the attachment system was attempted by way of unconsciously administered separation stimuli. In Experiments 1 and 3 (N = 29 and 89), the separation stimulus alluded to God, and in Experiment 2 (N = 47), it alluded to mother. Responses were moderated by perceived attachment history with parents in all experiments. Participants with secure histories increased in religious attachment behaviors, whereas those with insecure histories decreased following attachment system activation compared with control Stimulation. There also were suggestions of experimental group increase in proximity seeking in relation to God. The main co...
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debriefing after Subliminal Stimulation does information to participants prevent persistent effects
2004Co-Authors: Andreas Birgegard, Staffan SohlbergAbstract:Debriefing after Subliminal Stimulation: Does information to participants prevent persistent effects?
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memories of mother complementarity and shame predicting response to Subliminal Stimulation with mommy and i are one
Scandinavian Journal of Psychology, 2003Co-Authors: Staffan Sohlberg, Katja Claesson, Andreas BirgegardAbstract:Memories of Mother, Complementarity, and Shame: Predicting Response to Subliminal Stimulation with "Mommy and I are One".
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Persistent complex Subliminal activation effects: first experimental observations.
Journal of Personality and Social Psychology, 2003Co-Authors: Staffan Sohlberg, Andreas BirgegardAbstract:A strong recent focus on unconscious processes has increased interest in Subliminal Stimulation and other experimental activation technologies. Five experiments using male and female university stu ...
Elisa Raffaella Ferre - One of the best experts on this subject based on the ideXlab platform.
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Subliminal Stimulation and somatosensory signal detection
Acta Psychologica, 2016Co-Authors: Elisa Raffaella Ferre, Maneesh Sahani, Patrick HaggardAbstract:Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from Subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that Subliminal somatosensory Stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the Subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, Subliminal somatosensory Stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that Subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that Subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals.
