Learning strategy refinement reverses early sensory cortical map expansion but not behavior: Support for a theory of directed cortical substrates of learning and memory.
Learning strategy refinement reverses early sensory cortical map expansion but not behavior: Support for a theory of directed cortical substrates of learning and memory.
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DOI：
10.1016/j.nlm.2015.10.006
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发表时间：
2015-12
影响因子：
2.7
通讯作者：
Weinberger NM
中科院分区：
文献类型：
--
作者：
Elias GA;Bieszczad KM;Weinberger NM
初级感觉皮层领域发展高度特定的联想表征可塑性，特别是扩大了其地形图内的强化信号刺激的代表面积。然而，过度训练后，他们已经解决了一个工具性任务可以减少或消除的扩展，而成功的行为仍然存在。由于这种可塑性的发展取决于用于解决任务的学习策略，我们询问扩展的损失是否是由于过度训练期间使用的策略。成年雄性大鼠在三声听觉辨别任务中接受训练，以压到CS+以获得水奖励，并在CS-音和沉默的试验间隔期间避免这样做;错误受到闪光和超时惩罚。小组获得了这个任务的一个标准，在七个培训课程，依靠一个策略，这是“酒吧新闻从音调开始错误信号”（“TOTE”）。然后三组接受不同程度的过度训练：ST组，无; RT组，一周; OT组，三周。他们的初级听觉场（A1）的训练后映射显示，ST组和RT组已经开发了显着扩大的代表性领域，特别是限于CS+音的频带。相比之下，OT组的A1与幼稚对照组没有差异。对学习策略的分析表明，这组学生已经将策略转移到了TOTE的改进中，在TOTE中，他们在犯错误之前自我终止了压杆（“iTOTE”）。在所有动物中，iTOTE使用越多，A1中CS+的代表性越小。因此，皮质扩张的丧失可归因于策略的转变或改进。这种扩张的逆转是根据一种新的理论框架（CONCERTO）来考虑的，该框架强调了解决异常发现的脑功能的四个基本原则，并解释了为什么即使是微小的策略变化也会涉及相关脑部位的伴随变化，包括皮质扩张的逆转。
Primary sensory cortical fields develop highly specific associative representational plasticity, notably enlarged area of representation of reinforced signal stimuli within their topographic maps. However, overtraining subjects after they have solved an instrumental task can reduce or eliminate the expansion while the successful behavior remains. As the development of this plasticity depends on the learning strategy used to solve a task, we asked whether the loss of expansion is due to the strategy used during overtraining. Adult male rats were trained in a three-tone auditory discrimination task to bar-press to the CS+ for water reward and refrain from doing so during the CS− tones and silent intertrial intervals; errors were punished by a flashing light and time-out penalty. Groups acquired this task to a criterion within seven training sessions by relying on a strategy that was “bar-press from tone-onset-to-error signal” (“TOTE”). Three groups then received different levels of overtraining: Group ST, none; Group RT, one week; Group OT, three weeks. Post-training mapping of their primary auditory fields (A1) showed that Groups ST and RT had developed significantly expanded representational areas, specifically restricted to the frequency band of the CS+ tone. In contrast, the A1 of Group OT was no different from naïve controls. Analysis of learning strategy revealed this group had shifted strategy to a refinement of TOTE in which they self-terminated bar-presses before making an error (“iTOTE”). Across all animals, the greater the use of iTOTE, the smaller was the representation of the CS+ in A1. Thus, the loss of cortical expansion is attributable to a shift or refinement in strategy. This reversal of expansion was considered in light of a novel theoretical framework (CONCERTO) highlighting four basic principles of brain function that resolve anomalous findings and explaining why even a minor change in strategy would involve concomitant shifts of involved brain sites, including reversal of cortical expansion.