Orientation column

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

Inhibitory zones of receptive fields of the lateral geniculate body and visual cortex of the cat

Abstract: Unit responses to moving strips were investigated. The organization of the inhibitory zones in the receptive fields of the lateral geniculate body and visual cortex of the cat was compared. The response in the receptive field of the lateral geniculate body was inhibited only during simultaneous stimulation of the excitatory and inhibitory zones of the field. Stimulation of the inhibitory zone in the receptive field of the visual cortex was effective for a long time (several hundreds of milliseconds) after stimulation of the excitatory zone. The inhibitory zones of the simple and complex receptive fields of the visual cortex differed significantly. An increase in the width of the strip above the optimal size reduced the inhibitory effect in the complex fields. This was not observed in the simple receptive fields. The functional and structural models of the receptive field of the visual cortex are discussed.

Activation of orientation selectivity mechanisms in neurons of the cat visual cortex by a moving visual "noise" field

Abstract: A relationship was established between the response of neurons of the cat visual cortex and the direction of movement in the visual "noise" field and of a slit of light. It was shown that a shift in the preferred direction of movement in the "noise" field in relation to that of the slit was found in orientationally selective neurons only. It was concluded that the "noise" field, which is a stimulus lacking an orientation component, does activate mechanisms of neuronal orientation selectively.

Reorganization of Receptive Fields of Cortical Field 21a Neurons and Formation of Responses to Moving Visual Stimuli

Abstract: Using extracellular recording of spike activity from single neurons of field 21a of the cat neocortex, we examined in detail the spatial organization of receptive fields (RFs) of such cells after conditions of presentation of an immobile blinking light spot (a static RF) and moving visual stimuli (dynamic RFs). As was shown, the excitability of different RF subfields of a group of neurons possessing homogeneous on–off organization of the static RF changes significantly depended on the contrast, shape, dimension, orientation, and direction of movement of the applied mobile visual stimulus. This is manifested in changes in the number of discharge centers and shifts of their spatial localization. A hypothesis on the possible role of synchronous activation of the neurons neighboring the cell under study in the formation of an additional neuronal mechanism providing specialization of neuronal responses is proposed.

Alpha and Beta Oscillations in the Dynamics of the Areas and Weightings of the Receptive Fields of Striate Neurons in Cats in Classical and Combined Mapping

Abstract: Acute experiments on 22 anesthetized and immobilized cats were performed to produce dynamic time-slices maps of 83 on and/or off receptive fields of 47 visual cortex field 17 neurons using classical and combined mapping. These experiments showed that the areas and weightings of neuron fields during response generation using classical mapping changed in a wavelike manner. Mathematical processing of these data showed that the dynamics of receptive field characteristics consisted of the sum of a slow aperiodic and a rapid periodic component. The slow aperiodic component showed biphasic receptive field dynamics. The oscillation frequency of the periodic component in most cases was distributed into the alpha and, more rarely, beta EEG ranges. Additional activation of the discharge center of the receptive field of the neuron in combined mapping had no effect on the frequency of periodic oscillations but elicited significant reductions in the duration and amplitude of the aperiodic component. The mechanisms underlying the dynamics of neuron receptive fields in the primary visual cortex are discussed, as is the functional significance of these dynamics.