Attending to visual features causes modulations of neuronal activity in early visual cortex. Although the effect of such modulation on sensory cortex is relatively well understood, the nature of the their control signals remains unknown. We examined the attentional control signals for motion and color in two fMRI experiments. Subjects viewed a compound stimulus containing two superimposed motion directions (or colors), while alternating their attention between the two directions (or colors). They performed an attention-demanding change detection task on the attended stimulus. We found different attentional states (e.g., attending to red vs. green) did not produce reliable differences in fMRI response amplitude. However, using multi-voxel pattern analysis of fMRI data, we were able to decode subjects' attentional state in multiple brain regions. These regions include early visual areas (V1 to MT), as well as parietal and frontal areas (IPS and FEF) that are commonly associated with spatial attention. These results thus demonstrate that IPS and FEF are also responsible for attending to specific features, in addition to spatial locations. Our results provide the first evidence regarding the control signals associated with maintaining attention on a non-spatial feature value.
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