Rudolph K K, Ferrera V P, Pasternak T
Department of Psychology, University of Rochester, NY 14627-0270.
Vision Res. 1994 Dec;34(24):3241-51. doi: 10.1016/0042-6989(94)90063-9.
Dynamic random-dot targets were used to study neural mechanisms underlying motion perception. Performance of cats with severely reduced numbers of cortical directionally selective neurons (reduced DS) was compared to that of normal animals. We assessed the spatial properties of the residual motion mechanism by measuring direction discriminations at various dot displacements. At small displacements, reduced DS cats' motion integration thresholds for opposite direction discrimination were nearly normal. At larger displacements, their thresholds surpassed those of normal cats and their upper displacement limit (dmax) was increased by 0.35 deg. The accuracy of direction discrimination was reduced at small displacements, but at larger displacements direction difference thresholds of reduced DS cats approached or surpassed those of normals. These data were compared to the performance of humans who showed an extension of dmax for peripherally viewed targets. The data support the hypothesis that expansion in spatial scale of the motion mechanism may contribute to extension of dmax. Additional support for this hypothesis is provided by a modified direction discriminating line-element model. The model also suggests that changes in sampling of motion mechanisms in the reduced DS system may play a role.
动态随机点目标被用于研究运动感知背后的神经机制。将皮层方向选择性神经元数量大幅减少（减少DS）的猫的表现与正常动物的表现进行比较。我们通过测量不同点位移时的方向辨别来评估残余运动机制的空间特性。在小位移时，减少DS的猫在相反方向辨别的运动整合阈值接近正常。在大位移时，它们的阈值超过了正常猫的阈值，并且其上位移极限（dmax）增加了0.35度。在小位移时方向辨别准确性降低，但在大位移时，减少DS的猫的方向差异阈值接近或超过正常猫。这些数据与人类的表现进行了比较，人类对外周视觉目标的dmax有所延长。这些数据支持了运动机制空间尺度的扩展可能导致dmax延长的假设。一个修改后的方向辨别线元模型为这一假设提供了额外支持。该模型还表明，减少DS系统中运动机制采样的变化可能起作用。
