Babiloni Claudio, Babiloni Fabio, Carducci Filippo, Cappa Stefano, Cincotti Febo, Del Percio Claudio, Miniussi Carlo, Moretti Davide Vito, Pasqualetti Patrizio, Rossi Simone, Sosta Katiuscia, Rossini Paolo Maria
Dipartimento di Fisiologia Umana e Farmacologia Sezione di EEG ad Alta Risoluzione Università degli Studi di Roma "La Sapienza" P.le Aldo Moro 5 00185 Rome, Italy.
Neuroimage. 2004 Apr;21(4):1576-84. doi: 10.1016/j.neuroimage.2003.11.023.
Many recent neuroimaging studies of episodic memory have indicated an asymmetry in prefrontal involvement, with the left prefrontal cortex more involved than the right in encoding, the right more than the left in retrieval (hemispheric encoding and retrieval asymmetry, or HERA model). In this electroencephalographic (EEG) high-resolution study, we studied brain rhythmicity during a visual episodic memory (recognition) task. The theta (4-6 Hz), alpha (6-12 Hz) and gamma (28-48 Hz) oscillations were investigated during a visuospatial long-term episodic memory task including an encoding (ENC) and retrieval (RET) phases. During the ENC phase, 25 figures representing interiors of buildings ("indoor") were randomly intermingled with 25 figures representing landscapes ("landscapes"). Subject's response was given at left ("indoor") or right ("landscapes") mouse button. During the RET phase (1 h later), 25 figures representing previously presented "indoor" pictures ("tests") were randomly intermingled with 25 figures representing novel "indoor" ("distractors"). Again, a mouse response was required. Theta and alpha EEG results showed no change of frontal rhythmicity. In contrast, the HERA prediction of asymmetry was fitted only by EEG gamma responses, but only in the posterior parietal areas. The ENC phase was associated with gamma EEG oscillations over left parietal cortex. Afterward, the RET phase was associated with gamma EEG oscillations predominantly over right parietal cortex. The predicted HERA asymmetry was thus observed in an unexpected location. This discrepancy may be due to the differential sensitivity of neuroimaging methods to selected components of cognitive processing. The strict relation between gamma response and perception suggests that retrieval processes of long-term memory deeply impinged upon sensory representation of the stored material.
近期许多关于情景记忆的神经影像学研究表明，前额叶参与存在不对称性，即左前额叶皮质在编码过程中比右前额叶皮质参与更多，而右前额叶皮质在提取过程中比左前额叶皮质参与更多（半球编码和提取不对称性，即HERA模型）。在这项脑电图（EEG）高分辨率研究中，我们研究了视觉情景记忆（识别）任务期间的脑节律。在一个包括编码（ENC）和提取（RET）阶段的视觉空间长期情景记忆任务中，对θ（4 - 6Hz）、α（6 - 12Hz）和γ（28 - 48Hz）振荡进行了研究。在ENC阶段，25个代表建筑物内部（“室内”）的图形与25个代表风景（“风景”）的图形随机混合。受试者通过按鼠标左键（“室内”）或右键（“风景”）做出反应。在RET阶段（1小时后），25个代表先前呈现的“室内”图片（“测试”）的图形与25个代表新颖“室内”（“干扰物”）的图形随机混合。同样，需要鼠标做出反应。θ和α脑电图结果显示额叶节律没有变化。相比之下，HERA不对称性预测仅与脑电图γ反应相符，但仅在后顶叶区域。ENC阶段与左顶叶皮质上的γ脑电图振荡相关。之后，RET阶段主要与右顶叶皮质上的γ脑电图振荡相关。因此，在一个意想不到的位置观察到了预测的HERA不对称性。这种差异可能是由于神经影像学方法对认知加工选定成分的敏感性不同。γ反应与感知之间的严格关系表明，长期记忆的提取过程对存储材料的感觉表征有深刻影响。
