Gonzalo D, Shallice T, Dolan R
The Wellcome Department of Cognitive Neurology, University College London, 12 Queen Square, London, WC1N 3BG, United Kingdom.
Neuroimage. 2000 Mar;11(3):243-55. doi: 10.1006/nimg.2000.0540.
Functional imaging studies of learning and memory have primarily focused on stimulus material presented within a single modality (see review by Gabrieli, 1998, Annu. Rev. Psychol. 49: 87-115). In the present study we investigated mechanisms for learning material presented in visual and auditory modalities, using single-trial functional magnetic resonance imaging. We evaluated time-dependent learning effects under two conditions involving presentation of consistent (repeatedly paired in the same combination) or inconsistent (items presented randomly paired) pairs. We also evaluated time-dependent changes for bimodal (auditory and visual) presentations relative to a condition in which auditory stimuli were repeatedly presented alone. Using a time by condition analysis to compare neural responses to consistent versus inconsistent audiovisual pairs, we found significant time-dependent learning effects in medial parietal and right dorsolateral prefrontal cortices. In contrast, time-dependent effects were seen in left angular gyrus, bilateral anterior cingulate gyrus, and occipital areas bilaterally. A comparison of paired (bimodal) versus unpaired (unimodal) conditions was associated with time-dependent changes in posterior hippocampal and superior frontal regions for both consistent and inconsistent pairs. The results provide evidence that associative learning for stimuli presented in different sensory modalities is supported by neural mechanisms similar to those described for other kinds of memory processes. The involvement of posterior hippocampus and superior frontal gyrus in bimodal learning for both consistent and inconsistent pairs supports a putative function for these regions in associative learning independent of sensory modality.
学习与记忆的功能成像研究主要聚焦于单一模态下呈现的刺激材料（见加布里埃利1998年发表于《心理学年度评论》第49卷第87 - 115页的综述）。在本研究中，我们使用单试次功能磁共振成像技术，探究了视觉和听觉模态下呈现的学习材料的机制。我们在两种条件下评估了时间依赖性学习效应，这两种条件分别涉及呈现一致对（以相同组合重复配对）或不一致对（项目随机配对呈现）。我们还评估了相对于仅重复呈现听觉刺激的条件，双模态（听觉和视觉）呈现的时间依赖性变化。通过时间与条件分析来比较对一致和不一致视听对的神经反应，我们发现在内侧顶叶和右侧背外侧前额叶皮质存在显著的时间依赖性学习效应。相比之下，在左侧角回、双侧前扣带回以及双侧枕叶区域观察到了时间依赖性效应。对于一致和不一致对，配对（双模态）与未配对（单模态）条件的比较与后海马体和额上回的时间依赖性变化相关。结果提供了证据，表明不同感觉模态下呈现的刺激的联想学习由与其他类型记忆过程所描述的类似神经机制支持。后海马体和额上回在一致和不一致对的双模态学习中的参与，支持了这些区域在独立于感觉模态的联想学习中的假定功能。
