Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy
Dopamine Controls the Neural Dynamics of Memory Signals and Retrieval Accuracy
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DOI：
10.1038/npp.2013.141
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发表时间：
2013-11-01
影响因子：
7.6
通讯作者：
Bunzeck, Nico
中科院分区：
文献类型：
--
作者：
Apitz, Thore;Bunzeck, Nico
人类大脑能够快速区分新的和已经存储的信息，以实现最佳行为和决策。虽然新奇辨别的神经机制通常被描述为时间上恒定的（即，具有特定的潜伏期），但最近的电生理学研究表明，神经新奇信号的发生（即，对新项目和旧项目的事件相关反应的差异）可以通过奖励动机加速。虽然这种加速背后的确切生理机制尚不清楚，但神经递质多巴胺参与新奇感和奖励处理表明，在奖励前景的背景下，多巴胺水平的提高可能起作用。为了研究这一假设，我们使用脑磁图（MEG）结合了一个新/旧的识别记忆任务，在这个任务中，新旧项目之间的正确区分得到了奖励。重要的是，在任务之前，人类受试者接受了150毫克多巴胺前体左旋多巴或安慰剂。对于安慰剂组，旧/新信号在左颞/枕传感器上刺激开始后100 ms达到峰值。相反，在左旋多巴给药后，最早的旧/新效应仅在类似于400 ms后出现，并且检索准确性降低，如较低的d'值所表示的。因此，我们的研究结果指出了多巴胺在控制新旧信息之间区别的神经过程计时中的一个以前未报道的作用。他们还认为，这种关系遵循一种非线性函数，即多巴胺水平的轻微提高会加速神经/认知过程，而过量的多巴胺水平会损害它们。
The human brain is capable of differentiating between new and already stored information rapidly to allow optimal behavior and decision-making. Although the neural mechanisms of novelty discrimination were often described as temporally constant (ie, with specific latencies), recent electrophysiological studies have demonstrated that the onset of neural novelty signals (ie, differences in event-related responses to new and old items) can be accelerated by reward motivation. While the precise physiological mechanisms underlying this acceleration remain unclear, the involvement of the neurotransmitter dopamine in both novelty and reward processing suggests that enhanced dopamine levels in the context of reward prospect may have a role. To investigate this hypothesis, we used magnetoencephalography (MEG) in combination with an old/new recognition memory task in which correct discrimination between old and new items was rewarded. Importantly, before the task, human subjects received either 150 mg of the dopamine precursor levodopa or placebo. For the placebo group, old/new signals peaked at similar to 100 ms after stimulus onset over left temporal/occipital sensors. In contrast, after levodopa administration earliest old/new effects only emerged after similar to 400 ms and retrieval accuracy was reduced as expressed in lower d' values. As such, our results point towards a previously unreported role of dopamine in controlling the chronometry of neural processes underlying the distinction between old and new information. They also suggest that this relationship follows a nonlinear function whereby slightly enhanced dopamine levels accelerate neural/cognitive processes and excessive dopamine levels impair them.