Poster B4, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
To what extent do spatial attention and expectation rely on 'amodal' or modality-specific mechanisms?
Arianna Zuanazzi1, Uta Noppeney1; 1Computational Neuroscience and Cognitive Robotics Centre, University of Birmingham, UK
Attention and expectation are two critical mechanisms for guiding perceptual processes. Top-down attention favours efficient allocation of cognitive resources by prioritising relevant signals. Expectation facilitates perception by generating plausible templates of the forthcoming signals. Previous studies suggested that attention operates amodally, by similarly recruiting lower sensory areas and association cortices for signals in different sensory modalities. Yet, as these studies manipulated attention via stimulus probability, they confounded attention and expectation. Conversely, it is unknown whether expectations are formed via amodal or modality-specific mechanisms. To investigate whether spatial attention and expectation generalise across sensory modalities and rely on distinct mechanisms, the current functional magnetic resonance imaging (fMRI) study employed a novel multisensory approach that orthogonally manipulated spatial attention (i.e. task-relevance) and expectation (i.e. stimulus probability) selectively in audition and evaluated unisensory and multisensory effects on responses to auditory and visual signals. Presentation of stimuli in the unattended relative to attended hemifield increased the BOLD-response in the intraparietal sulcus (IPS) irrespective of stimulus modality suggesting that attentional shifts rely on largely amodal mechanisms in association cortices. By contrast, medial prefrontal cortices showed increased activations for expected relative to unexpected stimuli selectively for the auditory modality. Furthermore, low level visual and auditory areas showed increased activations indicating a prediction error signal selectively for unexpected auditory stimuli. In conclusion, our study showed that spatial attention and expectation rely on distinct neural systems. While attention relies on amodal mechanisms in IPS, expectation operates in a more modality-specific fashion leading to prediction errors in sensory areas.
Topic Area: ATTENTION: Multisensory