The Structure of Primary Visual Cortex Neuron Responses and its Interaction with the Dynamics of the Preferred Orientation

Orientational tuning of neurons in area V1 of the cat visual cortex has observed to undergo sequential shifts during response generation. In order to identify the mechanisms underlying this process, we investigated the dynamics of spike frequency in the responses of neurons to a flashing bar in different orientations, using principal components analysis and frequency analysis of the spike density function of these responses. The following observations were made: 1) the contribution of each component of the response depended on the orientation of the stimulus; 2) the components contained phasic and tonic constituents, as well as rhythmic oscillations in the θ/α/β ranges; 3) there was no correlational relationship between the phasic constituents or between the rhythmic oscillations in the same frequency range in different components. These data suggest that the dominance of components with different orientations changes during the development of responses, and this underlies the dynamics of V1 neuron orientational tuning.

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