Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD Maastricht, the Netherlands.
J Neurosci. 2011 Oct 19;31(42):14944-51. doi: 10.1523/JNEUROSCI.1046-11.2011.
Perceptual skills improve with daily practice (Fahle and Poggio, 2002; Fine and Jacobs, 2002). Practice induces plasticity in task-relevant brain regions during an "offline" consolidation period thought to last several hours, during which initially fragile memory traces become stable (Karni, 1996; Dudai, 2004). Impaired retention of a task if followed by training in another task is considered evidence for the instability of memory traces during consolidation (Dudai, 2004). However, it remains unknown when after training memory traces become stable and resistant against interference, where in the brain the neuronal mechanisms responsible for interference are localized, and how these mechanisms produce interference. Here, we show in human participants strong interference between two visual skill-learning tasks for surprisingly long time intervals between training periods (up to 24 h). Interference occurred during asymptotic learning, but only when stimuli were similar between tasks. This supports a strong contribution to interference of low-level visual cortical areas (Karni and Bertini, 1997; Ahissar and Hochstein, 2004), where similar stimuli recruit overlapping neuronal populations. Our finding of stimulus-dependent and time-independent interference reveals a fundamental limit in cortical plasticity that constrains the simultaneous representation of multiple skills in a single neuronal population, rather than a time-limited consolidation process.
知觉技能可以通过日常练习得到提高（Fahle 和 Poggio，2002；Fine 和 Jacobs，2002）。练习会在“离线”巩固期诱导与任务相关的大脑区域产生可塑性，据认为这个巩固期持续几个小时，在此期间，最初脆弱的记忆痕迹会变得稳定（Karni，1996；Dudai，2004）。如果在训练另一项任务后记忆保留受损，则被认为是巩固期间记忆痕迹不稳定的证据（Dudai，2004）。然而，目前尚不清楚记忆痕迹在训练后多久变得稳定且不易受干扰，负责干扰的神经元机制在大脑中的何处定位，以及这些机制如何产生干扰。在这里，我们在人类参与者中显示了两个视觉技能学习任务之间的强干扰，在训练期间的时间间隔（长达 24 小时）非常长。干扰发生在渐近学习期间，但仅当任务之间的刺激相似时才会发生。这支持了低水平视觉皮层区域（Karni 和 Bertini，1997；Ahissar 和 Hochstein，2004）对干扰有很强的贡献，在这些区域，相似的刺激会募集重叠的神经元群体。我们发现的刺激依赖性和时间独立性干扰揭示了皮质可塑性的基本限制，该限制限制了单个神经元群体中多个技能的同时表示，而不是时间限制的巩固过程。
