猫初级视皮层神经元视觉训练相关的方位调制特性可塑性变化研究

Vision dependent orientation tuning plasticity in primary cortex of cat

目的方位调制特性是V1区神经元最显著的特性之一,方位调制特性的发育具有视觉经验依赖的可塑性,本研究旨在定量测定和分析关键期后期幼猫V1区神经元由配对光栅视觉训练诱发的方位调制特性的可塑性变化。方法 采用在体细胞外记录技术,观察轻微麻醉和完全麻痹状态下3只幼猫初级视皮层V1区28个神经元的最优方位和方位选择指数(orientation selection index,OSI),采用非最优方位的高频配对光栅视觉训练13m in,观察训练后神经元最优方位偏移方向和偏移度大小,比较训练前后OSI的大小。结果 视觉训练后,最优方位在86%(24/28)的神经元中偏向训练刺激的方向(正偏离),在14%(4/28)的神经元中偏离训练刺激的方向(负偏离),平均偏移度为7.978°(SD=7.463°)。训练后OSI(0.199±0.096)较训练前OSI(0.159±0.078)增加,差异有统计学意义(t=-3.989,P<0.05)。结论 在发育关键期后期幼猫的初级视皮层,神经元具有明显的方位调制特性,感受野内非最优方位参数的光栅训练,通过高频配对刺激诱发的短时程突触传递效能可塑性变化的方式介导了神经元的方位调制特性的修饰变化。

Objective Orientation tuning is an important characteristics of neuron at V1 area, its development has experience-dependent plasticity. The establishment and decoration of orientation tuning in visual cortex was experience -dependent at early vision development. Present study was to investigate the effect of high frequency pairedgrating-conditioning on orientation tuning properties in primary visual cortex of cat. Methods Spike rates of 28 neurons to monocular presented gratings were assessed in Vl for 3 cats with in vivo extraceUular recording under anaesthesia and paralysis. Preferred orientation （POS） and orientation selection index （OSI） were computed. After conditioning for 13 minutes, the shift direction, shift degrees and OSI were investigated and compared. Results About 85% （24/28） of all neurons shifted their PO toward the conditioning orientation（ positive shift）. 14% （4/28） of all neurons shifted their PO away from the conditioning orientation（ negtive shift）. Mean DS was 7.978°（ SD = 7. 453, n = 28）. After conditioning, OSI were significantly improved （0. 199 ± 0. 095 vs. 0. 159 ± 0. 078 ; t = - 3. 989 ,P 〈 0.05 ）. Conclusions Orientation tuning property are fairly developed in primary visual cortex at the end of critical period. High frequency pairedgratings conditioning of non-preferred orientation may modulate the orientation tuning property of neurons through the mechanism of short-term synaptic plasticity.