Convergent evidence from behavior, psychophysics, ERP, and fMRI in humans, as well as single unit studies in animals highlights the importance of interactions across sensory modalities. However, there is still controversy about how early multisensory stimuli converge. One view holds that sensory streams converge in polymodal cortices only after being processed by unimodal cortices. This view does not exclude the possibility of feedback to unimodal cortical areas but is in contrast to the view that early unimodal cortices are affected by multisensory stimuli directly. While there is evidence that multisensory stimuli affect early sensory cortices, it has not been demonstrated that attention to a specific modality modulates the timing and spatial extent of multisensory interactions directly in humans. The goal of this project is to delineate the neural underpinnings and influence of attention on multisensory integration. We predict that when attention is directed to a sensory modality, unimodal stimuli will be enhanced at early latencies consistent with the view that intermodal attention modulates early sensory processing in the cortex. Furthermore, we predict that synchronous auditory and visual multisensory stimuli will elicit larger neural responses at latencies reflecting early sensory processing and that scalp distributions and source localization analyses will indicate that this modulation is occurring early in cortical processing. Finally, we predict that attention to different sensory modalities will result in further enhanced multisensory activity to the attended modality.
| Karns, Christina M; Knight, Robert T (2009) Intermodal auditory, visual, and tactile attention modulates early stages of neural processing. J Cogn Neurosci 21:669-83 |
| Moberget, Torgeir; Karns, Christina M; Deouell, Leon Y et al. (2008) Detecting violations of sensory expectancies following cerebellar degeneration: a mismatch negativity study. Neuropsychologia 46:2569-79 |
