Orientation column

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

Single-unit and 2-deoxyglucose studies of side inhibition in macaque striate cortex (visual cortex/side stopping/side-band inhibition/surround inhibition/contour perception)

Abstract: In the course of studies to map spatial fre- quency tuning of neurons in layers 2 and 3 of macaque striate cortex, we found that a high proportion (70%) of cells in the interblob regions responded poorly to full-field gratings, com- pared with responses to single bars, edges, or delimited grat- ings. This was most often due to side inhibition, in which increasing the number of cycles of a grating placed within the cell's receptive field causes progressive inhibition of response. Quantitative receptive-field mappings showed, however, that the inhibition can occur within the region activated by a bar, as well as beyond it. The inhibition appears to be orientation- selective, in that a surround grating was more effective at inhibiting the response to a center grating patch if it was of similar orientation. 2-Deoxyglucose experiments confirmed that side inhibition is very widespread in the interblobs of layers 2 and 3 and suggested that it is reduced or lacking in layers 4A through 6. Since layers 2 and 3 of striate cortex are the major source of cortical projections to area V2 and beyond, the prevalence of side stopping in these laminae has implica- tions for theories of cortical visual function. Side-stopped interblob cells may be acting as "contour-pass filters" that filter out redundant information in textured or noisy surfaces, focusing subsequent form processing on contrasts correspond- ing to object boundaries.

[Receptive fields of cat striate neurons: dynamics of weight and topographical characteristics of the excitatory zone of the neuron receptive fields in the visual cortex].

Abstract: In 22 acute experiments on anesthetized and immobilized adult cats, the dynamics of 83 on- and/or off-receptive fields (RF) was studied in 47 striate neurons with the method of temporal slices by mapping with single-flash stimuli. The latency of the RF appearance was 88 +/- 5 ms, and its duration was 192 +/- 12 ms. Dynamical wavy changes in the RF sizes and weights repeating up to three times were revealed. The mean duration of one wave was 95 +/- 4 ms. In 99% of cases, the RF discharge center defined for one temporal slice also displaced in an undulatory way relatively the RF's center defined for whole analysis period. The mean duration of this undulatory cycle was 67.3 +/- 3 ms. In 72.5% of cases, the displacement of the discharge center followed different trajectories inscribed in an ellipse. The functional significance of such changes in the RFs of striate neurons is discussed with regard to the dynamics of their detector features and underlying mechanisms.

An Investigation of the Development of Ocular Dominance and Orientation Columns in Cat Striate Cortex Using 2-Deoxyglucose

Abstract: Neurophysiological studies on the striate cortex of immature cats have indicated that although oriented neurones occur they are broadly tuned and have a more imprecise columnar organization. Similarly transneuronal autoradiography reveals an initially incomplete segregation of the geniculo-cortical afferents. We have used 2-deoxyglucose autoradiography to examine the development of columnar metabolic label in the striate cortex of normal and binocularly deprived kittens following either monocular stimulation or stimulation with fixed orientations. In normal animals, both orientation and ocular dominance columns achieve an adultlike pattern at 5–6 weeks of age and indications of periodic labelling in both stimulus conditions are first apparent at 3 weeks. After stimulation with fixed orientations at 3 weeks, discrete foci of increased labelling are seen in layer IV; it is only in older animals that a full columnar pattern appears. At 3 weeks, ocular dominance columns extend through all cortical layers both ipsilateral and contralateral to the stimulated eye; the columns become more regular in older animals. Binocular deprivation appears to inhibit the formation of orientation columns as defined by de-oxyglucose autoradiography; only in one 35 day old cat was there an indication of columnar labelling. Ocular dominance columns were less affected by binocular deprivation; at both 5 weeks and 3 months there was definite periodic label although the distribution in the younger animal was less regular than in a comparable normal animal.