Influence Of Salience Of Visual Stimuli Outside Receptive Field On Response Of Neurons In Cat Primary Visual Cortex

Objective:To Study influence of salience of visual stimuli outside receptive field on response of neurons in cat primary visual cortex.Methods:With in vivo extracellular recording techniques and cluster analysis method, we tested the response of neurons in the primary visual cortex of adult cat under anesthesia. Visual stimuli inside and outside receptive field with different saliency were given to the cat. Compute Spike rate, response latency and Variability under every stimuli by draw Post-stimulus time-histograms(PSTH) by spike2.The spike rate could be normalized to the only receptive field stimuli response. Statistic analysis was completed by SPSS13.0.Results:1.The spatial summation curve:Visual stimuli of a grating whose size was2-30degree.We could get the size of classic receptive field (CRF) by the curve. The response latency and the variability of the neurons under the stimuli with30°diameter is shorter than under the stimuli within CRF (p<0.05)2. Influence on response of neurons under stimuli inside CRF with different contrast stimuli outside of the CRF:Visual stimuli of different contrast (100%、70%、50%、30%or10%) out of CRF with the stimuli in CRF was given to cat. There are inhibition response and facilitation response by the normalized response. With the contrast of nCRF stimuli decreasing, the influence of the nCRF stimuli to neurons decreased. In inhibition response the more and more cell becomes facilitation. In facilitation neurons, the relationship between normalized response and contrast fit quadratic model:y=1.160+1.911x-1.554x2(y:normalized response, x:contrast of stimuli in nCRF),p=0.026.3. Influence on response of neurons under stimuli inside CRF with different direction stimuli outside CRF:when the direction of stimuli outside receptive field is crossed with the grating in CRF, the effect of the stimuli on neurons response was decresed.In facilitation neurons it fit the quadratic model in5%.4. Influence on response of neurons under stimuli inside CRF with different topology stimuli outside CRF:when the topology of stimuli outside receptive field is Ring or C, the effect of the stimuli on neurons response decreased. In facilitation response which both fit the quadratic model in15%.5. Influence on response of neurons under stimuli of different contrast inside CRF with stimuli outside CRF:A visual stimulus inside CRF on different contrast (70%,50%,30%, or10%) with stimuli outside CRF whose contrast was same with the CRF stimuli or100%contrast was gived to cat. The modulation effect of stimuli outside CRF with100%contrast was bigger than those whose contrast is equal to the CRF stimuli.6.Gap effect:gap effect could increase the spike rate (p<0.05)Conclusions:The effect of visual stimuli saliency outside of CRF on neurons in primary cortex changed with saliency changing. Gap effect plays an important role in the modulation of visual stimuli outside of CRF to neurons.