Ursino Mauro, Magosso Elisa, Cuppini Cristiano
Department of Electronics, Computer Science, and Systems, University of Bologna, viale Risorgimento 2, I-40136 Bologna, Italy.
Vision Res. 2008 Jun;48(13):1456-70. doi: 10.1016/j.visres.2008.04.002. Epub 2008 May 16.
A mathematical model of orientation selectivity in a single hypercolumn of the primary visual cortex developed in a previous work [Ursino, M., & La Cara, G.-E. (2004). Comparison of different models of orientation selectivity based on distinct intracortical inhibition rules. Vision Research, 44, 1641-1658] was used to analyze the possible mechanisms underlying tilt aftereffect (TAE). Two alternative models are considered, based on a different arrangement of intracortical inhibition (an anti-phase model in which inhibition is in phase opposition with excitation, and an in-phase model in which inhibition has the same phase arrangement as excitation but wider orientation selectivity). Different combinations of parameter changes were tested to explain TAE: a threshold increase in excitatory and inhibitory cortical neurons (fatigue), a decrease in intracortical excitation, an increase or a decrease in intracortical inhibition, a decrease in thalamo-cortical synapses. All synaptic changes were calculated on the basis of Hebbian (or anti-Hebbian) rules. Results demonstrated that the in-phase model accounts for several literature results with different combinations of parameter changes requiring: (i) a depressive mechanism to neurons with preferred orientation close to the adaptation orientation (fatigue of excitatory cortical neurons, and/or depression of thalamo-cortical synapses directed to excitatory neurons, and/or depression of intracortical excitatory synapses); (ii) a facilitatory mechanism to neurons with preferred orientation far from the adaptation orientation (fatigue of inhibitory cortical neurons, and/or depression of thalamo-cortical synapses directed to inhibitory neurons, and/or depression of intracortical inhibitory synapses). By contrast, the anti-phase model appeared less suitable to explain experimental data.
在之前的一项工作中[乌尔西诺，M.，& 拉卡拉，G.-E.（2004年）。基于不同皮质内抑制规则的不同方向选择性模型的比较。《视觉研究》，44，1641 - 1658]所建立的初级视觉皮层单个超柱中方向选择性的数学模型，被用于分析倾斜后效（TAE）潜在的可能机制。基于皮质内抑制的不同排列考虑了两种替代模型（一种反相模型，其中抑制与兴奋相位相反；一种同相模型，其中抑制与兴奋具有相同的相位排列，但方向选择性更宽）。测试了参数变化的不同组合来解释TAE：兴奋性和抑制性皮质神经元的阈值增加（疲劳）、皮质内兴奋的降低、皮质内抑制的增加或降低、丘脑 - 皮质突触的减少。所有突触变化均基于赫布（或反赫布）规则进行计算。结果表明，同相模型通过不同的参数变化组合解释了多项文献结果，这些组合需要：（i）对偏好方向接近适应方向的神经元的抑制机制（兴奋性皮质神经元的疲劳，和/或指向兴奋性神经元的丘脑 - 皮质突触的抑制，和/或皮质内兴奋性突触的抑制）；（ii）对偏好方向远离适应方向的神经元的促进机制（抑制性皮质神经元的疲劳，和/或指向抑制性神经元的丘脑 - 皮质突触的抑制，和/或皮质内抑制性突触的抑制）。相比之下，反相模型似乎不太适合解释实验数据。
