Shevelev I A
Institute of Higher Nervous Activity and Neurophysiology, Russian Acad. Sciences, Moscow, Russia.
Ross Fiziol Zh Im I M Sechenova. 1999 Jun;85(6):767-80.
About 40% of neurons (114/289) studied in the cat area 17 gave a larger (by 3.06 +/- 0.32 times on average) response to a flashed cross, corner or y-like figures centered in the RF than to an optimal single bar. Most such neurons (72%) were found to be highly selective both to shape (angle between the lines) and to orientation of these figures. In the studied neuronal selection we have also found all possible types of invariance of sensitivity to orientation and/or shape of these figures. Separated and combined stimulation of RF center and surrounding area revealed in 44 units summation, antagonism or absence of interaction of these zones by the selectivity index (cross/bar response ratio). Cross-sensitivity was investigated in 85 V1 neurons before, during and after local blockade of GABAA ergic inhibition by microiontophoretical application of bicuculline. Inhibition either emerged or increased cross-sensitivity (32% of cells), or depressed it (36% of cases), while in some neurons it does not influenced the function. Possible mechanisms of the described effects are discussed as well as their functional implication for second-order feature extraction in the visual cortex: selective or invariant sensitivity of neurons to the shape and orientation of the line-crossings.
在猫的17区研究的约40%的神经元（114/289）对以其感受野为中心闪现的十字、角或Y形图形的反应比对最佳单线条的反应更大（平均大3.06±0.32倍）。发现大多数此类神经元（72%）对这些图形的形状（线条间角度）和方向都具有高度选择性。在研究的神经元选择中，我们还发现了对这些图形的方向和/或形状敏感性的所有可能类型的不变性。通过选择性指数（十字/线条反应比率），对44个单位的感受野中心和周边区域进行单独和联合刺激，揭示了这些区域的总和、拮抗或无相互作用情况。在通过微量离子电泳应用荷包牡丹碱局部阻断GABAA能抑制之前、期间和之后，对85个V1神经元进行了交叉敏感性研究。抑制作用要么出现或增加交叉敏感性（32%的细胞），要么降低交叉敏感性（36%的情况），而在一些神经元中它不影响该功能。文中讨论了所描述效应的可能机制及其对视觉皮层二阶特征提取的功能意义：神经元对线条交叉形状和方向的选择性或不变敏感性。
