The visual system is well equipped for processing corners even at early stages along the visual hierarchy. Already in primary visual cortex, the outputs from endstopped cells can account for the percept of a corner (Rodrigues & du Buf,
2006), albeit not by means of individual neurons but through a network of multiple detector units (Roelfsema, Lamme, Spekreijse, & Bosch,
2002). Single neurons selective for stimulus characteristics like the sign of curvature, the polarity of angles, or the angular value itself have been reported no earlier than V2 (Ito & Komatsu,
2004). A considerable portion of orientation selective V2 neurons exhibit a bimodal response profile tuned to two different orientations within the same receptive field (Anzai, Peng, & Van Essen,
2007). Although bimodal specifity is a necessary condition for corner detection, these V2 neurons are still unfit for corner detection since their responses to the optimal angle is indistinguishable from the response to either orientation component (Ito & Komatsu,
2004). Specialized corner detectors finally emerge in area V4, where many cells respond preferentially to corners and curves but not the constituting orientations in isolation (Pasupathy & Connor,
2002). Given that recent studies have also proposed area V4 as one of the main loci of contour integration (Chen et al.,
2014; Gilad, Meirovithz, & Slovin,
2013), it stands to reason that contour detection may benefit from the presence of corner elements along a contour.