112,058 research outputs found
Looming sounds enhance orientation sensitivity for visual stimuli on the same side as such sounds
No full textSeveral recent multisensory studies show that sounds can influence visual processing. Some visual judgments can be enhanced for visual stimuli near a sound occurring around the same time. A recent TMS study (Romei et al. 2009) indicates looming sounds might influence visual cortex particularly strongly. But unlike most previous behavioral studies of possible audio-visual exogenous effects, TMS phosphene thresholds rather than judgments of external visual stimuli were measured. Moreover, the visual hemifield assessed relative to the hemifield of the sound was not varied. Here, we compared the impact of looming sounds to receding or "static" sounds, using auditory stimuli adapted from Romei et al. (2009), but now assessing any influence on visual orientation discrimination for Gabor patches (well-known to involve early visual cortex) when appearing in the same hemifield as the sound or on the opposite side. The looming sounds that were effective in Romei et al. (2009) enhanced visual orientation sensitivity (d0) here on the side of the sound, but not for the opposite hemifield. This crossmodal, spatially specific effect was stronger for looming than receding or static sounds. Similarly to Romei et al. (2009), the differential effect for looming sounds was eliminated when using white noise rather than structured sounds. Our new results show that looming structured sounds can specifically benefit visual orientation sensitivity in the hemifield of the sound, even when the sound provides no information about visual orientation itself. © The Author(s) 2011
Auditory stimulus timing influences perceived duration of co-occurring visual stimuli
No full textThere is increasing interest in multisensory influences upon sensory-specific judgments, such as when auditory stimuli affect visual perception. Here we studied whether the duration of an auditory event can objectively affect the perceived duration of a co-occurring visual event. On each trial, participants were presented with a pair of successive flashes and had to judge whether the first or second was longer. Two beeps were presented with the flashes. The order of short and long stimuli could be the same across audition and vision (audio–visual congruent) or reversed, so that the longer flash was accompanied by the shorter beep and vice versa (audio–visual incongruent); or the two beeps could have the same duration as each other. Beeps and flashes could onset synchronously or asynchronously. In a further control experiment, the beep durations were much longer (tripled) than the flashes. Results showed that visual duration discrimination sensitivity (d′) was significantly higher for congruent (and significantly lower for incongruent) audio–visual synchronous combinations, relative to the visual-only presentation. This effect was abolished when auditory and visual stimuli were presented asynchronously, or when sound durations tripled those of flashes. We conclude that the temporal properties of co-occurring auditory stimuli influence the perceived duration of visual stimuli and that this can reflect genuine changes in visual sensitivity rather than mere response bias
Folchetto e l'eccellenza d'amore (Paradiso IX, 97-102)
No full textL’articolo si concentra sui tre paragoni mitologici che compaiono nell’autopresentazione di Folchetto di Marsiglia nel nono canto del Paradiso. L’analisi vuole mettere in luce soprattutto la strategia dantesca di allusione alle Heroides di Ovidio, da cui gli exempla sono tratti, inquadrate storicamente all’interno della pratica scolastica medievale della moralizzazione. Le figure di Didone, Fillide ed Ercole sono studiate nel dettaglio in considerazione della loro appartenenza all’opera ovidiana, così da mostrare le ragioni morali sottese alla scelta poetica di Dante. In particolare, si cerca di chiarire l’identità di «Iole» (v. 102), proponendone una parziale identificazione con la figura di Onfale alla luce della confusione sul nome della donna presente in alcuni commenti antichi e in generale nella cultura medievale
Slow Theta tACS of the Right Parietal Cortex Enhances Contralateral Visual Working Memory Capacity
No full textRecent research suggests alteration of visual working memory capacity by modulation of parietal theta frequency via transcranial alternating current stimulation (tACS). However, it remains to be clarified whether this effect is partly driven by co-stimulation of prefrontal cortex and subcortical structures. It was hypothesized that focal tACS over the parietal lobe without additional prefrontal or subcortical stimulation should lead to similar effects as reported in the literature. Healthy, young participants were tested on a visual working memory paradigm while receiving either focal parietal tACS at 4 Hz, at 7 Hz or sham stimulation. Focal right posterior 4 Hz tACS led to increased working memory capacity strictly for the visual hemifield contralateral to stimulation. Exclusive stimulation of posterior cortex by 4 Hz tACS replicates effects recently reported in literature, confirming that stimulation of the prefrontal cortex or subcortical structures are not a primary driver of these observations
Typical Lateral Interactions, but Increased Contrast Sensitivity, in Migraine-With-Aura
No full textIndividuals with migraine show differences in visual perception compared to control groups. It has been suggested that differences in lateral interactions between neurons might account for some of these differences. This study seeks to further establish the strength and spatial extent of excitatory and inhibitory interactions in migraine-with-aura using a classic lateral masking task. Observers indicated which of two intervals contained a centrally presented, vertical Gabor target of varying contrast. In separate blocks of trials, the target was presented alone or was flanked by two additional collinear, high contrast Gabors. Flanker distances varied between 1 and 12 wavelengths of the Gabor stimuli. Overall, contrast thresholds for the migraine group were lower than those in the control group. There was no difference in the degree of lateral interaction in the migraine group. These results are consistent with the previous work showing enhanced contrast sensitivity in migraine-with-aura for small, rapidly presented targets, and they suggest that impaired performance in global perceptual tasks in migraine may be attributed to difficulties in segmenting relevant from irrelevant features, rather than altered local mechanisms
Causal evidence that intrinsic beta frequency is relevant for enhanced signal propagation in the motor system as shown through rhythmic TMS
No full textCorrelative evidence provides support for the idea that brain oscillations underpin neural computations. Recent work using rhythmic stimulation techniques in humans provide causal evidence but the interactions of these external signals with intrinsic rhythmicity remain unclear. Here, we show that sensorimotor cortex precisely follows externally applied rhythmic TMS (rTMS) stimulation in the beta-band but that the elicited responses are strongest at the intrinsic individual beta-peak-frequency. While these entrainment effects are of short duration, even subthreshold rTMS pulses propagate through the network and elicit significant cortico-spinal coupling, particularly when stimulated at the individual beta-frequency. Our results show that externally enforced rhythmicity interacts with intrinsic brain rhythms such that the individual peak frequency determines the effect of rTMS. The observed downstream spinal effect at the resonance frequency provides evidence for the causal role of brain rhythms for signal propagation
La direttiva europea sul trasferimento di imprese. Profili generali
No full textIl saggio tratta dei profili generali della cessione dell'azienda alla luce della direttiva dell'Unione Europea e della giurisprudenza della Corte di Giustizi
Emotional Valence Modulates Low Beta Suppression and Recognition of Social Interactions
No full textEmotional valence may have evolutionary adaptive purposes as negative stimuli can be related to survival against threat and positive stimuli to facilitating relationships. This can be seen in the different impact positive and negative stimuli have on human health and well-being, and in the valence-specific cortical activity and neurophysiological patterns reported; for example, negative stimuli are processed more rapidly than positive. Valence-specific patterns are affected by individual differences and personality traits such as empathy, where levels of empathy relate to different reactivity patterns to valence. Here we investigated the effect of valence on neurophysiological responses and interpretation of social interactions depicted by point-light biological motion (PLBM) displays. The meaning of each PLBM display is revealed as the sequence unfolds and is therefore not readily available for snap assessments such as fight or flight responses. We compared electroencephalogram (EEG) reactivity during observation of the displays between individuals with low, moderate, or high levels of empathy. Results indicated that positive displays induced significantly larger suppression in lower beta (13 20 Hz) compared to control displays, while negative displays revealed no difference in suppression compared to scrambled versions. However, no difference between positive and negative displays was observed, suggesting that the rapid processing of negative displays may have been minimized by revealing meaning more slowly. Positive displays were interpreted more accurately, while levels of empathy did not modulate either neurophysiological responses or interpretation, suggesting that empathy under these conditions did not influence the way in which valence was processed or interpreted
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