Purchase this article with an account.
Rudiger von der Heydt, Nan R. Zhang; Analysis of the context integration mechanism in border ownership coding. Journal of Vision 2009;9(8):903. doi: 10.1167/9.8.903.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Border ownership neurons in the visual cortex (V2, V1) show an influence of image context far beyond the classical receptive field (CRF) that emerges less than 30ms after response onset. The nature of the fast context integration mechanism is not well understood. Three different hypotheses have been proposed: (H1) suppression/facilitation from the non-classical surround (Sakai and Nishimura, J. Cogn. Neurosci. 2006); (H2) propagation of signals along the V2 contour representation (Zhaoping, Neuron 2005); (H3) feedback from higher-level cortex (Craft et al., J. Neurophysiol. 2007; Jehee et al., Vision Res. 2007).
To test these hypotheses we recorded neurons in area V2 of alert fixating macaques and studied border ownership modulation with fragmented figures. We used “Cornsweet figures” which can be fragmented without creation of new contours. The contours of squares were decomposed into four corners and four edges. While one edge was centered on the CRF, the presence of the fragments outside the CRF was varied (factorial design).
Cornsweet figures generated border ownership signals nearly as strong as solid figures. The fragments outside the CRF produced facilitation on the preferred border ownership side as well as suppression on the non-preferred side. In the mean across cells, all locations on either side contributed about equally. Fragments far from the CRF influenced the responses also in the absence of fragments closer to the CRF, and without the extra delay that would be expected from intracortical propagation, arguing against H2. About four of the seven fragments on either side contributed significantly, on average, whereas H1 predicts that no more than one or two would have an influence. The results were consistent with H3, namely feedback from a higher-level area close to V2, which allows all parts of the contours to influence the responses independently and implies no differential delays.
This PDF is available to Subscribers Only