Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, University Clinic, 72076 Tübingen, Germany.
Network. 2009;20(4):197-232. doi: 10.3109/09548980903314204.
Early in life, visual experience influences the refinement of the preferential response for specific stimulus features exhibited by neurons in the primary visual cortex. A striking example of this influence is the reduction in cortical direction selectivity observed in cats reared under high-frequency stroboscopic illumination. Although various mechanisms have been proposed to explain the maturation of individual properties of neuronal responses, a unified account of the joint development of the multiple response features of cortical neurons has remained elusive. In this study, we show that Hebbian synaptic plasticity accounts for the simultaneous refinement of orientation and direction selectivity under both normal and stroboscopic rearing, if one takes into account the spatiotemporal input to the retina during oculomotor activity. In a computational model of the LGN and V1, eye movements are sufficient to establish the patterns of thalamocortical activity required for a Hebbian refinement of both direction- and orientation-selective responses during exposure to natural stimuli. Furthermore, we show that consideration of fixational eye movements explains the simultaneous loss of direction selectivity and preservation of orientation selectivity observed as a consequence of stroboscopic rearing. These results further support a role for oculomotor activity in the refinement of the response properties of V1 neurons.
早期的视觉经验会影响初级视觉皮层神经元对特定刺激特征的优先反应的精细化。这种影响的一个显著例子是，在高频频闪照明下饲养的猫中观察到的皮层方向选择性的减少。尽管已经提出了各种机制来解释神经元反应的个体特性的成熟，但皮层神经元的多种反应特征的联合发展仍然难以解释。在这项研究中，我们表明，如果考虑到眼球运动期间视网膜的时空输入，赫布突触可塑性可以解释在正常和频闪饲养下方位和方向选择性的同时精细化。在 LGN 和 V1 的计算模型中，眼球运动足以建立在自然刺激下暴露时所需的丘脑皮质活动模式，以实现对方向和方位选择性反应的赫布式精细化。此外，我们表明，注视眼动的考虑解释了频闪饲养导致的方向选择性的同时丧失和方位选择性的保留。这些结果进一步支持眼球运动在 V1 神经元反应特性的精细化中的作用。
