A NEUROBIOLOGICAL MODEL OF VISUAL-ATTENTION AND INVARIANT PATTERN-RECOGNITION BASED ON DYNAMIC ROUTING OF INFORMATION

We present a biologically plausible model of an attentional mechanism for forming position- and scale-invariant representations of objects i n the visual world. The model relies on a set of control neurons to dy namically modify the synaptic strengths of intracortical connections s o that information from a windowed region of primary visual cortex (V1 ) is selectively routed to higher cortical areas. Local spatial relati onships (i.e., topography) within the attentional window are preserved as information is routed through the cortex. This enables attended ob jects to be represented in higher cortical areas within an object-cent ered reference frame that is position and scale invariant. We hypothes ize that the pulvinar may provide the control signals for routing info rmation through the cortex. The dynamics of the control neurons are go verned by simple differential equations that could be realized by neur obiologically plausible circuits. In preattentive mode, the control ne urons receive their input from a low-level ''saliency map'' representi ng potentially interesting regions of a scene. During the pattern reco gnition phase, control neurons are driven by the interaction between t op-down (memory) and bottom-up (retinal input) sources. The model resp ects key neurophysiological, neuroanatomical, and psychophysical data relating to attention, and it makes a variety of experimentally testab le predictions.