The Advantage in Being Magnocellular: a Few More Remarks on Attention and the Magnocellular System

We have recently proposed a model of visual processing in which object recognition through the ventral stream into inferotemporal cortex is facilitated by an initial rapid feedforward sweep through the dorsal stream activating parietal and frontal regions prior to subsequent feedback to primary visual cortex (V1). Modulation of inferotemporal cortex also requires feedback from frontal regions, and horizontal connections from the dorsal stream. Aspects of this model, however, have been called into question-in particular the timing advantage of magnocellular over parvocellular arrivals in V1 (the 'magnocellular advantage'), the link between attention and the magnocellular system, and also the role of MT in smooth pursuit and saccadic eye movements. These criticisms are each rebutted in detail here, and the basis for a model derived from the magnocellular advantage is reaffirmed.