Haruno Masahiko, Kuroda Tomoe, Doya Kenji, Toyama Keisuke, Kimura Minoru, Samejima Kazuyuki, Imamizu Hiroshi, Kawato Mitsuo
Computational Neuroscience Laboratories, Advanced Telecommunications Research Institute, Kyoto 619-0288, Japan.
J Neurosci. 2004 Feb 18;24(7):1660-5. doi: 10.1523/JNEUROSCI.3417-03.2004.
Humans can acquire appropriate behaviors that maximize rewards on a trial-and-error basis. Recent electrophysiological and imaging studies have demonstrated that neural activity in the midbrain and ventral striatum encodes the error of reward prediction. However, it is yet to be examined whether the striatum is the main locus of reward-based behavioral learning. To address this, we conducted functional magnetic resonance imaging (fMRI) of a stochastic decision task involving monetary rewards, in which subjects had to learn behaviors involving different task difficulties that were controlled by probability. We performed a correlation analysis of fMRI data by using the explanatory variables derived from subject behaviors. We found that activity in the caudate nucleus was correlated with short-term reward and, furthermore, paralleled the magnitude of a subject's behavioral change during learning. In addition, we confirmed that this parallelism between learning and activity in the caudate nucleus is robustly maintained even when we vary task difficulty by controlling the probability. These findings suggest that the caudate nucleus is one of the main loci for reward-based behavioral learning.
人类能够通过试错获得能使奖励最大化的适当行为。最近的电生理和成像研究表明，中脑和腹侧纹状体中的神经活动编码了奖励预测误差。然而，纹状体是否是基于奖励的行为学习的主要位点尚待研究。为了解决这个问题，我们对一项涉及金钱奖励的随机决策任务进行了功能磁共振成像（fMRI），在该任务中，受试者必须学习涉及不同任务难度（由概率控制）的行为。我们使用从受试者行为中得出的解释变量对fMRI数据进行了相关分析。我们发现尾状核的活动与短期奖励相关，此外，还与学习过程中受试者行为变化的幅度平行。此外，我们证实，即使通过控制概率来改变任务难度，尾状核中学习与活动之间的这种平行关系也能得到有力维持。这些发现表明，尾状核是基于奖励的行为学习的主要位点之一。
