Xiao Lu-Qi, Zhang Jun-Yun, Wang Rui, Klein Stanley A, Levi Dennis M, Yu Cong
State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing 100875, China.
Curr Biol. 2008 Dec 23;18(24):1922-6. doi: 10.1016/j.cub.2008.10.030. Epub 2008 Dec 8.
Practice improves discrimination of many basic visual features, such as contrast, orientation, and positional offset. Perceptual learning of many of these tasks is found to be retinal location specific, in that learning transfers little to an untrained retinal location. In most perceptual learning models, this location specificity is interpreted as a pointer to a retinotopic early visual cortical locus of learning. Alternatively, an untested hypothesis is that learning could occur in a central site, but it consists of two separate aspects: learning to discriminate a specific stimulus feature ("feature learning"), and learning to deal with stimulus-nonspecific factors like local noise at the stimulus location ("location learning"). Therefore, learning is not transferable to a new location that has never been location trained. To test this hypothesis, we developed a novel double-training paradigm that employed conventional feature training (e.g., contrast) at one location, and additional training with an irrelevant feature/task (e.g., orientation) at a second location, either simultaneously or at a different time. Our results showed that this additional location training enabled a complete transfer of feature learning (e.g., contrast) to the second location. This finding challenges location specificity and its inferred cortical retinotopy as central concepts to many perceptual-learning models and suggests that perceptual learning involves higher nonretinotopic brain areas that enable location transfer.
练习可提高对许多基本视觉特征的辨别能力,如对比度、方向和位置偏移。人们发现,许多此类任务的知觉学习具有视网膜位置特异性,即学习很少能迁移到未经训练的视网膜位置。在大多数知觉学习模型中,这种位置特异性被解释为学习发生在视网膜拓扑早期视觉皮层位点的一个指标。另一种未经检验的假设是,学习可能发生在一个中枢位点,但它由两个独立的方面组成:学习辨别特定的刺激特征(“特征学习”),以及学习处理刺激位置处的局部噪声等与刺激无关的因素(“位置学习”)。因此,学习无法迁移到从未进行过位置训练的新位置。为了验证这一假设,我们开发了一种新颖的双重训练范式,即在一个位置采用传统的特征训练(如对比度),并在第二个位置同时或在不同时间对无关特征/任务(如方向)进行额外训练。我们的结果表明,这种额外的位置训练能够使特征学习(如对比度)完全迁移到第二个位置。这一发现挑战了位置特异性及其推断出的皮层视网膜拓扑结构,而它们是许多知觉学习模型的核心概念,并表明知觉学习涉及能够实现位置迁移的更高层次的非视网膜拓扑脑区。