19The Magnocellular (M) visual pathway is known as a fast route to convey coarse 20 information and facilitates object recognition by initiating top-down processes. It is 21 unclear what exact properties M pathway conveys to accelerate visual object processing. 22 Previous studies suggest that visual systems are highly sensitive to the perception of 23 topological property (TP), which remains unchanged under various shape changes, and 24 the TP is probably processed through a fast subcortical pathway. Here we hypothesize 25 that a subcortical M system contributes to the fast object recognition by processing TP 26 first. We first demonstrate that the facilitation effect of TP processing on object 27 perception occurs mainly in the M visual system, and then support the subcortical M 28 hypothesis of TP processing by the evidence that the early processing of TP was not 29 affected when cortical function was temporarily damaged by the transcranial magnetic 30 stimulation and when stimuli were biased to M system. 31 32 33 34 35The visual systems of animals are good at rapid detection of threat information in the 36 environment, which is a conserved and innate ability across species. It is commonly 37 considered that visual system has two major separate subdivisions, a magnocellular (M) 38 pathway responsible for fast processing of coarse information, and a parvocellular (P) 39 pathway for slow recognition of details (Callaway, 2005; de Haan and Cowey, 2011; 40 Livingstone and Hubel, 1987; Merigan and Maunsell, 1993). Neuroimaging evidence 41 shows that fast M projections conveying low spatial frequencies facilitate visual object 42 recognition by initiating top-down processes from orbitofrontal to the visual cortex (Bar 43 et al., 2006; Kveraga et al., 2007). However, it is unclear which geometric properties 44 of objects M pathway conveys to accelerate visual object processing. So far, the most 45 commonly exploited functional distinctions between the M and P pathways have been 46 the different sensitivity in spatial and temporal domains, as well as different responses 47to luminance contrast and color. The M pathway prefers lower spatial frequency and 48 higher temporal frequency, and is highly sensitive to low luminance contrast, while 49 entirely 'blind' to chromatic stimuli. The P pathway, by contrast, is more sensitive to 50 stimuli with a higher spatial-frequency but lower temporal-frequency, color-sensitive, 51 but weaker response to low contrast (< 8%) stimuli (de Valois et al., Lee et al., 1990; Tootell et al., 1988). Meanwhile, the M and P pathways are known as 54 the classical "where" and "what" pathways, which are considered to be mainly located 55 in the dorsal and ventral pathways of the cortex, respectively. Physiological evidence 56 yet demonstrates that the superficial layer of the superior colliculus (SC), a subcortical 57 brain area, shows little color-related activity, and predominantly responses to 58 achromatic information (Schiller et al., 1979; White et al., 2009), which is similar to M...