Orientation column

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

Subdomains within orientation columns of primary visual cortex

Abstract: In the mammalian visual system, early stages of visual form processing begin with orientation-selective neurons in primary visual cortex (V1). In many species (including humans, monkeys, tree shrews, cats, and ferrets), these neurons are organized in a beautifully arrayed pinwheel-like orientation columns, which shift in orientation preference across V1. However, to date, the relationship of orientation architecture to the encoding of multiple elemental aspects of visual contours is still unknown. Here, using a novel, highly accurate method of targeting electrode position, we report for the first time the presence of three subdomains within single orientation domains. We suggest that these zones subserve computation of distinct aspects of visual contours and propose a novel tripartite pinwheel-centered view of an orientation hypercolumn.

Lateral inhibition in cortical filters

Abstract: This work presents explorations in the microstructure of natural vision systems based on large scale computer simulations Similarly to previous work in this area we compute the functional inner products of a two dimensional input signal image with a set of two dimensional Gabor functions which have been shown to t the receptive elds of simple cells in the primary visual cortex of mammals These inner products are then considered as net inputs to the cortical cells and used to compute the cell activations as non linear functions A previously used model is extended with a pixel wise winner takes all competition between di erent Gabor lters which is introduced in order to model lateral inhibition between cortical cells The e ect of lateral inhibition is qualitatively estimated by visualization of computed cortical images and quantitatively evaluated by applying the model to a face recognition problem Recognition rate of was achieved on a database of face images of persons vs achieved with a previously used model

Relationship between preferred orientation and ordinal position in neurones of cat striate cortex.

Abstract: Striate cortical cells were classified according to whether or not their preferred orientation was close to one of the "primary" orientations (horizontal, vertical or radial, i.e. directed to the area centralis) and according to their ordinal position on the afferent pathway from the dorsal lateral geniculate nucleus (dLGN). Among the neurones that could be driven monosynaptically from the dLGN, there was a high representation of those with a preference for the primary orientations. This was particularly evident in the case of C (complex) cells. There was no such preponderance of primary orientations among the polysynaptically activated cells. It is proposed that the asymmetry of distribution seen among the first-order cells reflects the asymmetry seen subcortically in neurones that show orientation biases. It may be that the cortex elaborates a more uniform representation of orientations only at the higher ordinal levels.

Response Characteristics of Single Neurons in the Rabbit Visual Cortex

Abstract: Unitary discharges were extracellularly recorded from cortical cells in the rabbit's visual area. Most of the cortical units were responsive to large-field illumination which was turned on and off at about 0.8/sec. Response characteristics of cortical cells were largely similar to those of retinal ganglion cells. One hundred and twenty-nine units which were analyzed successfully were categorized into four classes according to the features of their receptive fields: simple, asymmetric, complex and compound. Especially, compound receptive fields were so named on the basis of the finding that the whole receptive field consisted of three separable complex fields. A columnar arrangement of cortical neurons was suggested on the basis of the fact that the localization of the receptive fields of units involved in a particular column was almost identical in the visual field. No other common properties to specialize the column was detected. Most of the receptive fields of units which were localized in the visual streak were oval in shape with their long axis horizontal as described in retinal ganglion cells. It is likely that in the rabbit's visual cortex no more elaborate analysis is made on in-coming visual information, but rather some integrative action is carried out for further processing.