Dissertation
Dissertation > Biological Sciences > Physiology > Neurophysiology

Information Processing Mechanism of Neuron Responses to Joint Multiple Stimulus Features in Cat's Primary Visual Cortex

Author LeiTaiLong
Tutor LiChaoYi
School University of Electronic Science and Technology
Course Biophysics
Keywords Primary visual cortex Non-classical receptive field Orientation Spatialfrequency Feature integration
CLC Q42
Type Master's thesis
Year 2013
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Natural objects is composed of different feature attributes, and integrating discrete perceptual visual features into consistent objects or events, is a key function of the visual system, and it has become one of the core issues of cognitive science and neuroscience. The vast majority neurons of mammalian visual cortex exist a feature selective receptive field, and most of them simultaneously have a selective response to multiple feature attributes of stimulation. Whether there is interaction among these responses and what extent of it have a directly major impact on the visual integration.In this thesis, the nervous response to a wide range of visual stimulation with a various combination of orientation and spatial frequency is discussed. Then the information processing mechanism of responses of non-classical receptive field (nCRF) to joint multiple stimulus features in cat primary visual cortex are preliminary investigated:1. We have studied spike signal of primary visual cortex neurons to understand the impact of joint multiple features (e.g., orientation, spatial frequency) on the nCRF information integration. The nCRF stimulation was found to significantly enhance complex cells’orientation selectivity, and it was found no obvious rule of spatial frequency selectivity.2. By comparising primary visual cortial neurons’ orientation selectivity in different spatial frequency, impact of nCRF on the dynamics of feature selectivity. We found complex cells of primary visual cortex existed different optimal orientation and bandwidth of tuning in different spatial frequency. The variation magnitude would change accordingly while stimulation covered to nCRF, this change can be divided into four types. Inseparability index αSVD of thirty-two percent of neurons gradually reduced with increasing stimulus size, moreover, αSVD of remaining neurons reduced with increasing stimulus size at first, and then it raised to a peak while stimulus expanded to5,3and2times size of the classic receptive field, along with stimulus falling outside the index reduced again.In summary, nCRF stimulation not only enhanced complex cells’orientation selectivity, but also changed the dynamic tuning between orientation and spatial frequency, which may indicate that primary visual cortex improved the capability of the visual cortex to process feature interaction information through simultaneously processing various features.

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