Oscillatory signatures of crossmodal congruence effects: An EEG investigation employing a visuotactile pattern matching paradigm

Abstract

Coherent percepts emerge from the accurate combination of inputs from the different sensory systems. There is an ongoing debate about the neurophysiological mechanisms of crossmodal interactions in the brain, and it has been proposed that transient synchronization of neurons might be of central importance. Oscillatory activity in lower frequency ranges (<30Hz) has been implicated in mediating long-range communication as typically studied in multisensory research. In the current study, we recorded high-density electroencephalograms while human participants were engaged in a visuotactile pattern matching paradigm and analyzed oscillatory power in the theta- (4-7Hz), alpha- (8-13Hz) and beta-bands (13-30Hz). Employing the same physical stimuli, separate tasks of the experiment either required the detection of predefined targets in visual and tactile modalities or the explicit evaluation of crossmodal stimulus congruence. Analysis of the behavioral data showed benefits for congruent visuotactile stimulus combinations. Differences in oscillatory dynamics related to crossmodal congruence within the two tasks were observed in the beta-band for crossmodal target detection, as well as in the theta-band for congruence evaluation. Contrasting ongoing activity preceding visuotactile stimulation between the two tasks revealed differences in the alpha- and beta-bands. Source reconstruction of between-task differences showed prominent involvement of premotor cortex, supplementary motor area, somatosensory association cortex and the supramarginal gyrus. These areas not only exhibited more involvement in the pre-stimulus interval for target detection compared to congruence evaluation, but were also crucially involved in post-stimulus differences related to crossmodal stimulus congruence within the detection task. These results add to the increasing evidence that low frequency oscillations are functionally relevant for integration in distributed brain networks, as demonstrated for crossmodal interactions in visuotactile pattern matching in the current study.

Oscillatory brain activity during multisensory attention reflects activation, disinhibition, and cognitive control

“…Given that we only analysed activity within 500 ms after change onset, this negative finding concurs with the results of Göschl et al 11 who found visual-tactile congruence effects building up only after 400 ms to 1100 ms11. (Unfortunately, we could not analyse this later time window in our data because it overlaps with the presentation of the second intensity change.)…”

“…In typical studies demonstrating early multisensory congruence effects, mostly detection or categorisation tasks are employed in which cross-modal congruence per se is task-irrelevant1046. Overall, the results of Göschl et al 11 and from our study indicate that if cross-modal congruence is task-relevant, early multisensory congruence effects seem to be diminished.…”

“…Top-down control was supposed to be associated with increased frontal theta-band oscillations as well as increased low frequency phase coupling16. Finally, since previous studies have associated beta-band oscillations with attentional processes17 and the evaluation of crossmodal congruence11, we also assumed to find modulated beta-band activity.…”

“…In a tactile discrimination task, Kanayama et al 10 varied the ratio of congruent and incongruent visual-tactile stimuli and demonstrated that top-down expectancy had an influence on oscillatory power in the theta and gamma range10. Göschl et al 11 employed a visual-tactile pattern matching task and found task-specific spectral signatures for theta-, alpha-, and beta-power depending on the cognitive demands11. Functional coupling analyses on a subset of their data revealed that large-scale synchronisations in the beta range might promote multisensory integration12.…”

A matter of attention: Crossmodal congruence enhances and impairs performance in a novel trimodal matching paradigm

“…Early sensory processing should reflect the aforementioned gain adjustments and thus should not differ between attentional conditions. Congruence relations should systematically affect cortical processing at later stages of processing, for instance in temporal, parietal and/or frontal regions (Göschl, Friese, Daume, König, & Engel, 2015).…”