Orientation column

About: Orientation column is a research topic. Over the lifetime, 1142 publications have been published within this topic receiving 130169 citations.

An edge detection model with neuron like organization

Abstract: Based on the Gabor function model of simple cortical cells,by imitating the structure of orientation columns in visual cortex, and aided by pattern enhancement and processing nets, a model for edge detection with neuron like organization is constructed. Simulation results show that its detection capability is comparable to that of the advanced edge detection algorithms of the smoothing spacial differentiation type in vogue. It is shown that this model as intuitively based on the early concept of edge detectors is essentially identical in the underlying mechanism to the latter. The proposed model provides a prototype for edge detection using electronic optical techniques and artificial neural nets.

An uncertainty principle underlying the pinwheel structure in the primary visual cortex

Abstract: The visual information in V1 is processed by an array of modules called orientation preference columns. In some species including humans, orientation columns are radially arranged around singular points like the spokes of a wheel, that are called pinwheels. The pinwheel structure has been observed first with optical imaging techniques and more recently by in vivo two-photon imaging proving their organization with single cell precision. In this research we provide evidence that pinwheels are de facto optimal distributions for coding at the best angular position and momentum. In the last years many authors have recognized that the functional architecture of V1 is locally invariant with respect to the symmetry group of rotations and translations SE(2). In the present study we show that the orientation cortical maps used to construct pinwheels can be modeled as coherent states, i.e. the configurations best localized both in angular position and angular momentum. The theory we adopt is based on the well known uncertainty principle, introduced by Heisenberg in quantum mechanics and later extended to many other groups of invariance. Here we state a corresponding principle in the cortical geometry with SE(2) symmetry, and by computing its minimizers we obtain a model of orientation activity maps in the cortex. As it is well known the pinwheels configuration is directly constructed from these activity maps, and we will be able to formally reproduce their structure starting from the group symmetries of the functional architecture of the visual cortex. The primary visual cortex is then modeled as an integrated system in which the set of simple cells implements the SE(2) group, the horizontal connectivity implements its Lie algebra and the pinwheels implement its minimal uncertainty states.

Bio-inspired orientation analysis for seismic image

Abstract: In this paper, we propose a novel method of orientation analysis for seismic image. Unlike conventional methods of orientation estimation with a context window, our method is inspired by the neural mechanism of visual perception in the biological brain. In the brain, the primary visual cortex contains orientation columns, which is composed of an array of simple cells as orientation detectors. A log-Gabor filter with a specific orientation and scale configuration simulates the neuronal mechanism of the simple cell, while an array of such orientation detectors simulates the neuronal responses of the orientation columns. The resulting orientation is derived at the pixel level of the input seismic image: the neuronal response of each simple cell competes with other cells in the same orientation column for the same pixel, and the winning neuron with maximum response defines the perceived orientation. We applied the proposed method to seismic interpretation to analyze the orientation patterns, and it also can be used as a general image orientation analysis tool.

Role of the contralateral cortex on the receptive field properties in the visual cortex of cats

Abstract: The aim of this series of experiments was to evaluate the receptive field properties of visual cells receiving part of their input the corpus callosum. Normal (control) and chiasma sectioned cats were recorded using conventional methods. The recording sites were the 17-18 border and the lateral suprasylvian (LS) cortex. The results indicated (a) the ocular dominance distribution was shifted towards the ipsilateral eye in the split chiasma cats; (b) orientation tunning and/or directional specificity were identical for the two eyes; (c) R.F. positions of binocular cells were also similar for each eye and were clustered near the vertical meridian, which they sometimes straddled; (d) R.F. sizes were larger in L.S. than in primary visual cortex but generally of equal dimensions for each eye. The results are interpreted with respect to the various functions which have been postulated for the corpus callosum.

Asymmetry of the internal connections of the striate cortex of the cat in the projection zone of the center of the field of vision

Abstract: Studies were carried out on the organization of the internal connections of the striate cortex in cats in the projection zone of the center (0–5°) of the field of vision by microintophoretic application of horseradish peroxidase to electrophysiologically identified orientational columns. The area containing neurons showing retrograde labeling in most cases extended in the mediolateral direction. Labeled cells were located in the upper (II, III) and lower (V, VI) layers of the cortex, and the shapes and orientations of the areas containing labeled neurons in these layers coincided. Spatial asymmetry was detected in the distribution of labeled neurons relative to the orientational column studied. Labeled cells were located predominantly medial to the columns, regardless of the distance from the projection of the area centralis. Considering the visuotopical map of field 17, the asymmetry detected here provides evidence that neurons in orientational columns have more extensive connections with neurons of the peripheral part of the cortex. An asymmetrical distribution of “silent” zones around the receptive fields of neurons in orientational columns is suggested, and that these appear to receive influences from the periphery of the visual field.