Walton Mark E, Bannerman David M, Rushworth Matthew F S
Department of Experimental Psychology, Oxford, OX1 3UD, United Kingdom.
J Neurosci. 2002 Dec 15;22(24):10996-1003. doi: 10.1523/JNEUROSCI.22-24-10996.2002.
We conducted a series of experiments to elucidate the role of rat medial frontal cortex (MFC) (including prelimbic, infralimbic, and cingulate cortices) in effort-based decision making. Rats were trained on a cost-benefit T-maze task in which they could either choose to climb a barrier to obtain a high reward in one arm (HR arm) or could obtain a small reward in the other with no barrier present (LR arm). Before surgery, all animals were selecting the HR arm on almost every trial. However, after excitotoxic lesions to MFC, the rats shifted to selecting the LR arm on almost every trial. This was not caused by a spatial memory or motor deficit because the same rats returned to selecting the HR arm when the amount of effort needed to be expended to obtain reward in either arm was equalized by putting an identical barrier in the LR arm. Additional experiments demonstrated that the change in effort-based decisions observed in the rats was not caused by a complete insensitivity to reward and effort because they returned to choosing the HR arm if either the cost was reduced (by making the barrier smaller) or the benefit was increased (increasing the food ratio differential). Instead, the MFC lesion shifted the animals' decision criterion, making them more likely to choose the LR arm than the sham-lesioned animals. These results imply that medial frontal cortex is important for allowing the animal to put in more work to obtain greater rewards.
我们进行了一系列实验，以阐明大鼠内侧前额叶皮质（MFC）（包括前边缘、边缘下和扣带回皮质）在基于努力的决策中的作用。大鼠接受了一项成本效益T迷宫任务训练，在该任务中，它们可以选择攀爬障碍物以在一个臂中获得高奖励（高奖励臂），或者在没有障碍物的另一个臂中获得小奖励（低奖励臂）。手术前，所有动物几乎在每次试验中都选择高奖励臂。然而，在对MFC进行兴奋性毒性损伤后，大鼠几乎在每次试验中都转向选择低奖励臂。这不是由空间记忆或运动缺陷引起的，因为当通过在低奖励臂中放置相同的障碍物使获得两个臂中奖励所需付出的努力量相等时，同一只大鼠又回到选择高奖励臂。额外的实验表明，在大鼠中观察到的基于努力的决策变化不是由对奖励和努力完全不敏感引起的，因为如果成本降低（通过使障碍物变小）或收益增加（增加食物比例差异），它们会再次选择高奖励臂。相反，MFC损伤改变了动物的决策标准，使它们比假手术动物更有可能选择低奖励臂。这些结果表明内侧前额叶皮质对于使动物付出更多努力以获得更大奖励很重要。
