Cite as:
Castaldi E, Frijia F, Montanaro D, Tosetti M, Morrone M C, 2011, "Selective human BOLD responses to chromatic spatial features " Perception 40 ECVP Abstract Supplement, page 11

Selective human BOLD responses to chromatic spatial features

E Castaldi, F Frijia, D Montanaro, M Tosetti, M C Morrone

Physiological and psychophysical evidence suggests that segmentation of an equiluminant visual scene into distinct objects could be achieved by a local energy algorithm computation, which relies on combining even- and odd-symmetric receptive field mechanisms. We measured BOLD responses to Fourier amplitude-matched edge and line stimuli, and to an amplitude-matched random noise control: all stimuli could be modulated either in luminance or in red-green (equiluminant) colour contrast. For equiluminant stimuli, alternation between congruent versus random-phase stimuli, as well as between edge and lines stimuli, produced no activation of primary visual cortex, indicating the existence of phase-selective colour neurons as early as V1. Only higher hierarchical areas, either along the dorsal pathway (caudal part of the intraparietal sulcus and V7) and along the ventral pathway (V4) responded with a preference for edges to line stimuli. The activity elicited by stimuli modulated in luminance confirmed previous results [Perna et al, 2008 Journal of Vision 8(10):15, 1–15]. Overall the results suggest the existence of equal numbers of neurones with even and odd receptive fields, for both luminance and colour stimuli in V1, as well as a specialization both along the dorsal and the ventral pathways for the detection of edges, both colour and luminance.

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