Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102, USA.
Neuropsychologia. 2011 Oct;49(12):3320-6. doi: 10.1016/j.neuropsychologia.2011.08.005. Epub 2011 Aug 11.
It has been proposed that reversal learning is impaired following damage to the orbitofrontal and ventromedial frontal cortex (OFC/VMFC) and to the medial temporal lobe (MTL), including the hippocampal formation. However, the exact characteristics of the MTL-associated reversal learning deficit are not known. To investigate this issue, we assessed 30 newly diagnosed patients with amnestic mild cognitive impairment (aMCI) and 30 matched healthy controls. All patients fulfilled the aMCI criteria of the Mayo Clinic Alzheimer's Disease Research Center and underwent head magnetic resonance imaging that confirmed MTL atrophy. Reversal learning was assessed using a novel reinforcement learning task. Participants first acquired and then reversed stimulus-outcome associations based on negative and positive feedback (losing and gaining points). Stimuli consisted of a cue (geometric shapes) and a spatial context (background color or pattern). Neuropsychological assessment included tasks related to the MTL (paired associates learning), dorsolateral prefrontal cortex (DLPFC) (extradimensional shift, One-touch Stockings of Cambridge), and OFC/VMFC (Holiday Apartment Task). Results revealed that, relative to controls, patients with aMCI exhibited a marked reversal learning deficit, which was highly selective for the reversal of context. The acquisition of stimulus-outcome associations and cue reversal learning were spared. Performance on the context reversal learning task significantly correlated with the right hippocampal volume. In addition, patients with aMCI had deficits on tests related to DLPFC but not to OFC/VMFC. However, DLPFC dysfunctions were not associated with context reversal learning. These results suggest that MTL deficits in aMCI selectively affect context reversal learning when OFC/VMFC functions are spared. This deficit is not influenced by the valence of the outcome (positive or negative feedback) and by executive dysfunctions.
据提议，在眶额和腹内侧前额皮质（OFC/VMFC）以及内侧颞叶（MTL），包括海马结构受损后，反转学习受损。然而，MTL 相关的反转学习缺陷的确切特征尚不清楚。为了研究这个问题，我们评估了 30 名新诊断的遗忘型轻度认知障碍（aMCI）患者和 30 名匹配的健康对照者。所有患者均符合 Mayo 诊所阿尔茨海默病研究中心的 aMCI 标准，并接受了头部磁共振成像检查，以确认 MTL 萎缩。反转学习通过一项新的强化学习任务进行评估。参与者首先根据负反馈（失分）和正反馈（得分）获得并反转刺激-结果关联。刺激由提示（几何形状）和空间上下文（背景颜色或图案）组成。神经心理学评估包括与 MTL 相关的任务（配对联想学习）、背外侧前额叶皮质（DLPFC）（外维度转换、剑桥 One-touch Stockings）和 OFC/VMFC（假日公寓任务）。结果显示，与对照组相比，aMCI 患者表现出明显的反转学习缺陷，这对上下文的反转具有高度选择性。刺激-结果关联和提示反转学习不受影响。上下文反转学习任务的表现与右侧海马体积显著相关。此外，aMCI 患者在与 DLPFC 相关的测试中存在缺陷，但与 OFC/VMFC 无关。然而，DLPFC 功能障碍与上下文反转学习无关。这些结果表明，在 OFC/VMFC 功能正常的情况下，aMCI 中的 MTL 缺陷选择性地影响上下文反转学习。这种缺陷不受结果的效价（正反馈或负反馈）和执行功能障碍的影响。
