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A variety of computational tasks in early vision can be formulated through lattice networks. The cooperative action of these networks depends on the topology of interconnections, both feedforward and recurrent ones. This paper shows that it is possible to consider a distinct general architectural solution for all recurrent computations of any given order.(More)
Eye position signals are pivotal in the visuomotor transformations performed by the posterior parietal cortex (PPC), but to date there are few studies addressing the influence of vergence angle upon single PPC neurons. In the present study, we investigated the influence on single neurons of the medial PPC area V6A of vergence and version signals.(More)
Interacting in the peripersonal space requires coordinated arm and eye movements to visual targets in depth. In primates, the medial posterior parietal cortex (PPC) represents a crucial node in the process of visual-to-motor signal transformations. The medial PPC area V6A is a key region engaged in the control of these processes because it jointly processes(More)
The ability of a real robot system to interact with the surrounding environment is subordinate to its ability of perceiving it correctly. Since the perception of depth directly relates to the ability of looking at the same point in space with both the cameras, i.e. to verge on a target object, it is essential for the system to gain a proper fixational(More)
A continuous-space model of visual cortex interactions which, starting from elongate Gaussian functions, leads to high-selective Gabor-like receptive fields, is proposed. The model is based on intracortical inhibition mechanisms occurring through medium-range clustered connections. The analysis, carried out under the assumption of a linear superposition of(More)
Within a linear field approach, an architectural model for simple cell direction selectivity in the visual cortex is proposed. The origin of direction selectivity is related to recurrent intracortical interactions with a spatially asymmetric character along the axis of stimulus motion. No explicit asymmetric temporal mechanisms are introduced or adopted.(More)
The problem of representing the visual signal in the harmonic space guaranteeing a complete characterization of its 2D local structure is investigated. Specifically, the efficacy of anisotropic versus isotropic filtering is analyzed with respect to general phase-based metrics for early vision attributes. We verified that the spectral information content(More)
We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth), from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a(More)
The efficacy of anisotropic versus isotropic filtering is analyzed with respect to general phase-based metrics for early vision attributes. We verified that the spectral information content gathered through oriented frequency channels is characterized by high compactness and flexibility, since a wide range of visual attributes emerge from different(More)
An architectural hypothesis for the origin of motion-in-depth selectivity in the visual cortex is proposed. On the basis of a time extension of the phase-based techniques for disparity estimation, we consider the computation of the total temporal derivative of the time-varying disparity through the combination of the responses of disparity energy units. The(More)