Multimodal control of selective attention: The role of parietal cortex during attentional shifts

Although the importance of the superior parietal lobule (SPL) for controls of visual attention is well established, its involvement in auditory and cross modal attentional control is less clear. Three experiments were designed examining brain activity of human observers during attentional shifts within auditory modality and between visual and auditory sensory modalities employing event related fMRI. Activation in auditory sensory areas increased following a shift to auditory modality and remained high during sustained auditory attention. Conversely, activation in visual sensory areas increased following a shift-to-visual modality event and remained high during sustained visual attention events. This result demonstrates the effects of top-down attentional modulation on the early sensory cortex of either modality. The time course of activity in SPL demonstrated a transient increase in activation following shifts of attention within and between modalities. This result suggests that the function of human SPL as the locus for control of top-down goal directed attention is not limited to visual modality, but rather consists of a more general mechanism that extends to within and cross modal attention control signals.