Neural Basics of Object-based Attention

In visual attention research, the identification of neural substrates of attention has proven to be one of the most basic questions. Psychophysical studies suggest attention to operate on spatial locations, on single stimulus features and on whole objects. While receiving increasing interest, still little is known about the neural principles of object-based attention. Recently, an explicit distinction between space-based and object-based mechanisms of attention could be achieved by directing subjects to attend to one of two spatially overlapping, transparent random dot surfaces. The study at hand used three variations of this paradigm to identify a neural correlate of object-based attention on the basis of single unit responses in the macaque brain. Changes in firing rates of single neurons in visual area MT, ranging from 12-74%, were shown to provide such a correlate. Moreover, the results presented suggest that both coherent motion criteria and surface color contribute to an attentional selection of surfaces in area MT